Horde Webmail file inclusion proof of concept & patch.

[ppelanne () hostgator com]

Horde 3.1.6 arbitrary file inclusion vulnerability, proof of concept & patch.

A severe security vulnerability affects any unix distribution running version 3.1.6 of the Horde webmail client 
included in most popular webhosting control panels. All previous versions are also affected and it is believed although 
not yet proven that Horde Groupware is also vulnerable.

Details are as follows:

David Collins and Patrick Pelanne along with the rest of the HostGator.com LLC support team discovered that Horde was 
not properly sanitizing POST variables for several options including it's themes. By maliciously modifying POST data 
sent to the client the attacker can modify the location of the theme variable and Horde will subsequently insert this 
information into it's database. By modifying this POST variable one can allow for directory traversal and file 
inclusion which can lead to full root privilege escalation.

Proof of concept:

Data injected through malicious tampering of POST data:

mysql> select * from horde_prefs where pref_uid='bbarker () hostgator com' and  pref_name='theme';
+-------------------------+------------+-----------+----------------------------------------------------------------------------------------------------------------------------+
| pref_uid                | pref_scope | pref_name | pref_value                                                         
                                                        |
+-------------------------+------------+-----------+----------------------------------------------------------------------------------------------------------------------------+
| bbarker () hostgator com | horde      | theme     | 
../../../../../../../../../../../../../../../../../../tmp/.horde/imp/attachments/bbarker () hostgator 
com/1204804402/t.txt  | 

Shown above, the malicious POST variable was inserted into the database and now points to the malicious code denoted by 
t.txt

A truncated strace shows the access and execution of the malicious code when the user enters the Horde webmail client:

31852 lstat64("/usr", {st_dev=makedev(3, 3), st_ino=2, st_mode=S_IFDIR|0755, st_nlink=18, st_uid=0, st_gid=0, 
st_blksize=4096, st_blocks=16, st_size=4096, s$
31852 lstat64("/usr/local", {st_dev=makedev(3, 3), st_ino=608001, st_mode=S_IFDIR|0755, st_nlink=26, st_uid=0, 
st_gid=0, st_blksize=4096, st_blocks=16, st_s$
31852 lstat64("/usr/local/cpanel", {st_dev=makedev(3, 3), st_ino=18539, st_mode=S_IFDIR|0711, st_nlink=37, st_uid=0, 
st_gid=10, st_blksize=4096, st_blocks=8$
31852 lstat64("/usr/local/cpanel/base", {st_dev=makedev(3, 3), st_ino=85078, st_mode=S_IFDIR|0755, st_nlink=21, 
st_uid=0, st_gid=0, st_blksize=4096, st_bloc$
31852 lstat64("/usr/local/cpanel/base/horde", {st_dev=makedev(3, 3), st_ino=85388, st_mode=S_IFDIR|0755, st_nlink=21, 
st_uid=32002, st_gid=32004, st_blksize$
31852 lstat64("/usr/local/cpanel/base/horde/config", {st_dev=makedev(3, 3), st_ino=115868, st_mode=S_IFDIR|0755, 
st_nlink=2, st_uid=32002, st_gid=32004, st_$
31852 lstat64("/usr/local/cpanel/base/horde/themes", {st_dev=makedev(3, 3), st_ino=86796, st_mode=S_IFDIR|0755, 
st_nlink=28, st_uid=32002, st_gid=32004, st_$
31852 lstat64("/tmp", {st_dev=makedev(7, 1), st_ino=2, st_mode=S_IFDIR|S_ISVTX|0777, st_nlink=9, st_uid=0, st_gid=0, 
st_blksize=4096, st_blocks=64, st_size=$
31852 lstat64("/tmp/.horde", {st_dev=makedev(7, 1), st_ino=38609, st_mode=S_IFDIR|0700, st_nlink=3, st_uid=32002, 
st_gid=32004, st_blksize=4096, st_blocks=2$
31852 lstat64("/tmp/.horde/imp", {st_dev=makedev(7, 1), st_ino=38610, st_mode=S_IFDIR|0700, st_nlink=3, st_uid=32002, 
st_gid=32004, st_blksize=4096, st_bloc$
31852 lstat64("/tmp/.horde/imp/attachments", {st_dev=makedev(7, 1), st_ino=38611, st_mode=S_IFDIR|0700, st_nlink=3, 
st_uid=32002, st_gid=32004, st_blksize=4$
31852 lstat64("/tmp/.horde/imp/attachments/patrick () hostgator com", {st_dev=makedev(7, 1), st_ino=38612, 
st_mode=S_IFDIR|0700, st_nlink=3, st_uid=32002, st$
31852 lstat64("/tmp/.horde/imp/attachments/patrick () hostgator com/1204804402", {st_dev=makedev(7, 1), st_ino=38613, 
st_mode=S_IFDIR|0700, st_nlink=2, st_ui$
31852 lstat64("/tmp/.horde/imp/attachments/patrick () hostgator com/1204804402/t.txt", {st_dev=makedev(7, 1), 
st_ino=38614, st_mode=S_IFREG|0600, st_nlink=1,$
31852 open("/tmp/.horde/imp/attachments/patrick () hostgator com/1204804402/t.txt", O_RDONLY) = 4

We have also included a patch below for this vulnerability tested on Horde v2.105.4.8 2006/07/29 16:49:19


--- horde/lib/Horde/Prefs.php   2008-03-06 21:14:38.000000000 -0600
+++ horde/lib/Horde/Prefs.patched       2008-03-06 20:10:56.000000000 -0600
@@ -325,12 +325,23 @@
         }

         return (isset($this->_prefs[$pref]['v'])) ?
-            ($convert ?
+            $this->_fixhole($pref,$convert ?
              $this->convertFromDriver($this->_prefs[$pref]['v'], $charset) :
              $this->_prefs[$pref]['v']) :
             null;
     }

+function _fixhole($pref,$value) {
+      $sanitize = '/^[a-z0-9._-]+$/i';
+      if (preg_match($sanitize, $value) && $pref == 'theme') {
+              return $value;
+      } elseif ($pref == 'theme') {
+                return "mozilla";
+      } else {
+                return $value;
+      }
+}
+
     function __get($name)
     {
         return $this->getValue($name);


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