Horde Webmail file inclusion proof of concept & patch.

Advisory Content :

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 (at) hostgator
(dot) com [email concealed]' and pref_name='theme';

+-------------------------+------------+-----------+--------------------
------------------------------------------------------------------------
--------------------------------+

| pref_uid | pref_scope | pref_name | pref_value

|

+-------------------------+------------+-----------+--------------------
------------------------------------------------------------------------
--------------------------------+

| bbarker (at) hostgator (dot) com [email concealed] | horde | theme
|
../../../../../../../../../../../../../../../../../../tmp/.horde/imp/att
achments/bbarker (at) hostgator (dot) com [email
concealed]/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 (at) hostgator (dot) com
[email concealed]", {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 (at) hostgator (dot) com
[email concealed]/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 (at) hostgator (dot) com
[email concealed]/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 (at) hostgator (dot) com
[email concealed]/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);

-- Begin Signature --

HostGator.com is looking for qualified systems administrators. Please send
an e-mail to jobs (at) hostgator (dot) com [email concealed] with your
resume!

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Horde Webmail file inclusion proof of concept & patch.