Changeset 5509 in subversion

Timestamp:

Nov 29, 2011 5:16:42 AM (18 months ago)

Author:

thomasb

Message:

Content filter for embedded attachments to protect from XSS on IE<=8 (#1487895)

Location:

trunk/roundcubemail

Files:

• CHANGELOG (modified) (1 diff)
• program/include/rcube_message.php (modified) (2 diffs)
• program/steps/mail/func.inc (modified) (2 diffs)
• program/steps/mail/get.inc (modified) (2 diffs)
• program/steps/mail/show.inc (modified) (1 diff)

trunk/roundcubemail/CHANGELOG

@@ -2 +2 @@
 ===========================
 
+- Add content filter for embedded attachments to protect from XSS on IE (#1487895)
 - Use strpos() instead of strstr() when possible (#1488211)
 - Fix handling HTML entities when converting HTML to text (#1488212)

trunk/roundcubemail/program/include/rcube_message.php

@@ -143 +143 @@
      * @return string URL or false if part does not exist
      */
-    public function get_part_url($mime_id)
+    public function get_part_url($mime_id, $embed = false)
     {
         if ($this->mime_parts[$mime_id])
-            return $this->opt['get_url'] . '&_part=' . $mime_id;
+            return $this->opt['get_url'] . '&_part=' . $mime_id . ($embed ? '&_embed=1' : '');
         else
             return false;
@@ -512 +512 @@
 
                 foreach ($this->inline_parts as $inline_object) {
-                    $part_url = $this->get_part_url($inline_object->mime_id);
+                    $part_url = $this->get_part_url($inline_object->mime_id, true);
                     if ($inline_object->content_id)
                         $a_replaces['cid:'.$inline_object->content_id] = $part_url;

trunk/roundcubemail/program/steps/mail/func.inc

@@ -552 +552 @@
  * @return string Clean HTML
  */
-function rcmail_wash_html($html, $p = array(), $cid_replaces)
+function rcmail_wash_html($html, $p, $cid_replaces)
 {
   global $REMOTE_OBJECTS;
@@ -1069 +1069 @@
         $out .= html::tag('hr') . html::p(array('align' => "center"),
           html::img(array(
-            'src' => $MESSAGE->get_part_url($attach_prop->mime_id),
+            'src' => $MESSAGE->get_part_url($attach_prop->mime_id, true),
             'title' => $attach_prop->filename,
             'alt' => $attach_prop->filename,

trunk/roundcubemail/program/steps/mail/get.inc

@@ -147 +147 @@
       header("Content-Disposition: $disposition; filename=\"$filename\"");
 
-      // turn off output buffering and print part content
-      if ($part->body)
-        echo $part->body;
-      else if ($part->size)
-        $IMAP->get_message_part($MESSAGE->uid, $part->mime_id, $part, true);
+      // do content filtering to avoid XSS through fake images
+      if (!empty($_REQUEST['_embed']) && $browser->ie && $browser->ver <= 8) {
+        if ($part->body)
+          echo preg_match('/<(script|iframe|object)/i', $part->body) ? '' : $part->body;
+        else if ($part->size) {
+          $stdout = fopen('php://output', 'w');
+          stream_filter_register('rcube_content', 'rcube_content_filter') or die('Failed to register content filter');
+          stream_filter_append($stdout, 'rcube_content');
+          $IMAP->get_message_part($MESSAGE->uid, $part->mime_id, $part, false, $stdout);
+        }
+      }
+      else {
+        // turn off output buffering and print part content
+        if ($part->body)
+          echo $part->body;
+        else if ($part->size)
+          $IMAP->get_message_part($MESSAGE->uid, $part->mime_id, $part, true);
+      }
     }
 
@@ -179 +192 @@
 
 
+
+/**
+ * PHP stream filter to detect html/javascript code in attachments
+ */
+class rcube_content_filter extends php_user_filter
+{
+  private $buffer = '';
+  private $cutoff = 2048;
+
+  function onCreate()
+  {
+    $this->cutoff = rand(2048, 3027);
+    return true;
+  }
+
+  function filter($in, $out, &$consumed, $closing)
+  {
+    while ($bucket = stream_bucket_make_writeable($in)) {
+      $this->buffer .= $bucket->data;
+
+      // check for evil content and abort
+      if (preg_match('/<(script|iframe|object)/i', $this->buffer))
+        return PSFS_ERR_FATAL;
+
+      // keep buffer small enough
+      if (strlen($this->buffer) > 4096)
+        $this->buffer = substr($this->buffer, $this->cutoff);
+
+      $consumed += $bucket->datalen;
+      stream_bucket_append($out, $bucket);
+    }
+
+    return PSFS_PASS_ON;
+  }
+}
+

trunk/roundcubemail/program/steps/mail/show.inc

@@ -133 +133 @@
         $ol .= html::tag('li', null,
           html::a(array(
-            'href' => $MESSAGE->get_part_url($attach_prop->mime_id),
+            'href' => $MESSAGE->get_part_url($attach_prop->mime_id, false),
             'onclick' => sprintf(
               'return %s.command(\'load-attachment\',{part:\'%s\', mimetype:\'%s\'},this)',