NGS000268 Technical Advisory: Symantec Messaging Gateway - Out-of-band stored-XSS delivered by email

[NCC Group Research <research () nccgroup com>]

=======
Summary
=======
Name: Symantec Messaging Gateway - Out-of-band stored-XSS delivered by email
Release Date: 30 November 2012
Reference: NGS00268
Discoverer: Ben Williams <ben.williams () ngssecure com>
Vendor: Symantec
Vendor Reference: 
Systems Affected: Symantec Messaging Gateway 9.5.3-3
Risk: Critical
Status: Published

========
TimeLine
========
Discovered: 17 April 2012
Released: 17 April 2012
Approved: 29 April 2012
Reported: 30 April 2012
Fixed: 27 August 2012
Published: 30 November 2012

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Description
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I. VULNERABILITY
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Symantec Messaging Gateway 9.5.3-3 - Out-of-band stored-XSS - delivered by email

II. BACKGROUND
-------------------------
Symantec Messaging Gateway 9.5.3-3 is the latest version, of their Email Security Appliance

III. DESCRIPTION
-------------------------
This issue means that an attacker can construct a malicious email message, containing arbitrary javascript in the 
subject line. When the message audit log is viewed (by an administrator) the script will execute in the context of the 
logged in admin.

This is a very serious issue, because the attack vector is a spam email, and the admin only has to view the messages in 
the audit log for the payload to execute. (Payloads could include any management or reconfiguration actions within the 
UI, or redirecting the user to other malicious content)

Additionally, the spam email containing the script can easily be made invisible within the UI, and/or damage the 
rendering of the UI to prevent itself from being noticed.

=================
Technical Details
=================
IV. PROOF OF CONCEPT
-------------------------
There are several ways to exploit this issue, here is an example using a script in the subject line, to produce a 
pop-up:

For example a message can be sent with the following subject line:

Something boring here..."><script>alert('Something nasty')</script>

Which could be sent with an automated script for example:

./sendEmail -s 192.168.1.59:25 -u "Something boring here...\"><script>alert('Something nasty')</script>" -f c () d com 
-t bob () insidetrust com -o message-file=spam1.txt 
(the body can contain any content)

Many thousands of messages can be sent in this way, until one is viewed by an administrator.

The message audit viewer affected is here:
http://192.168.1.59:41080/brightmail/status/message-audit/MessageAuditFlow$show.flo

This produces a test example pop-up when the message audit log is viewed
(Obviously, a "pop-up" is not the issue, this is just a proof of concept).

The issue is that the attacker can send an email message with any arbitrary javascript (or pull in javascript from 
another server) to perform actions within the UI, manage or reconfigure the device (with request forgery), disable 
protections or shutdown the appliance for example, perform session-hijacking or redirect the administrator to other 
malicious content.

===============
Fix Information
===============
An updated version of the software has been released to address the vulnerability:

http://www.symantec.com/security_response/securityupdates/detail.jsp?fid=security_advisory&pvid=security_advisory&year=2012&suid=20120827_00

NCC Group Research
http://www.nccgroup.com/research


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