[EFAIL] Don't decrypt PGP messages with no MDC protection (#6289)

CHANGELOG

@@ -8,6 +8,7 @@ CHANGELOG Roundcube Webmail
 - Fix bug where only attachments with the same name would be ignored on zip download (#6301)
 - Fix bug where unicode contact names could have been broken/emptied or caused DB errors (#6299)
 - Fix bug where after "mark all folders as read" action message counters were not reset (#6307)
+- Enigma: [EFAIL] Don't decrypt PGP messages with no MDC protection (#6289)
 
 RELEASE 1.3.6
 -------------

INSTALL

@@ -24,7 +24,7 @@ REQUIREMENTS
    - Net_IDNA2 0.1.1 or newer
    - Auth_SASL 1.0.6 or newer
    - Net_Sieve 1.3.2 or newer (for managesieve plugin)
-   - Crypt_GPG 1.6.0 or newer (for enigma plugin)
+   - Crypt_GPG 1.6.3 or newer (for enigma plugin)
    - Endroid/QrCode 1.6.0 or newer (https://github.com/endroid/QrCode)
 * php.ini options (see .htaccess file):
    - error_reporting E_ALL & ~E_NOTICE & ~E_STRICT

composer.json-dist

@@ -20,7 +20,7 @@
         "pear/net_idna2": "~0.2.0",
         "pear/mail_mime": "~1.10.0",
         "pear/net_smtp": "~1.7.1",
-        "pear/crypt_gpg": "~1.6.0",
+        "pear/crypt_gpg": "~1.6.3",
         "pear/net_sieve": "~1.4.0",
         "roundcube/plugin-installer": "~0.1.6",
         "endroid/qr-code": "~1.6.5"

plugins/enigma/lib/enigma_driver_gnupg.php

@@ -159,6 +159,16 @@ class enigma_driver_gnupg extends enigma_driver
                 $signature = $this->parse_signature($result['signatures'][0]);
             }
 
+            // EFAIL vulnerability mitigation (#6289)
+            // Handle MDC warning as an exception, this is the default for gpg 2.3.
+            if (method_exists($this->gpg, 'getWarnings')) {
+                foreach ($this->gpg->getWarnings() as $warning_msg) {
+                    if (strpos($warning_msg, 'not integrity protected') !== false) {
+                        return new enigma_error(enigma_error::NOMDC, ucfirst($warning_msg));
+                    }
+                }
+            }
+
             return $result['data'];
         }
         catch (Exception $e) {

plugins/enigma/lib/enigma_error.php

@@ -30,6 +30,7 @@ class enigma_error
     const BADPASS     = 5;
     const EXPIRED     = 6;
     const UNVERIFIED  = 7;
+    const NOMDC       = 8;
 
 
     function __construct($code = null, $message = '', $data = array())

plugins/enigma/lib/enigma_ui.php

@@ -894,6 +894,9 @@ class enigma_ui
                     $msg     = rcube::Q($this->enigma->gettext($label));
                     $this->password_prompt($status);
                 }
+                else if ($code == enigma_error::NOMDC) {
+                    $msg = rcube::Q($this->enigma->gettext('decryptnomdc'));
+                }
                 else {
                     $msg = rcube::Q($this->enigma->gettext('decrypterror'));
                 }

plugins/enigma/localization/en_US.inc

@@ -102,6 +102,7 @@ $messages['sigerror'] = 'Unverified signature. Internal error.';
 $messages['decryptok'] = 'Message decrypted.';
 $messages['decrypterror'] = 'Decryption failed.';
 $messages['decryptnokey'] = 'Decryption failed. Private key not found. Key ID: $keyid.';
+$messages['decryptnomdc'] = 'Decryption skipped. Message is not integrity protected.';
 $messages['decryptbadpass'] = 'Decryption failed. Invalid password.';
 $messages['decryptnopass'] = 'Decryption failed. Key password required.';
 $messages['decryptpartial'] = 'Message decrypted, but part of the body was not encrypted.';