Date: Thu, 22 Apr 2021 15:25:34 +0200
From: SEC Consult Vulnerability Lab <research@...-consult.com>
To: <fulldisclosure@...lists.org>
Subject: [FD] SEC Consult SA-20210422-0 :: Stored Cross Site Scripting
 (Outdated software library) in BMDWeb 2.0

SEC Consult Vulnerability Lab Security Advisory < 20210422-0 >
=======================================================================
              title: Stored Cross Site Scripting (Outdated software library)
            product: BMD BMDWeb 2.0
 vulnerable version: BMD versions prior to 24.01.21
      fixed version: 24.01.21 and 24.02.11 or higher
         CVE number: -
             impact: High
           homepage: https://www.bmd.com/
              found: 2021-02-11
                 by: Stefan Viehböck (Office Vienna)
                     SEC Consult Vulnerability Lab

                     An integrated part of SEC Consult, an Atos company
                     Europe | Asia | North America

                     https://www.sec-consult.com

=======================================================================

Vendor description:
-------------------
"BMD develops high-quality business software and is one of the leading software
manufacturers in Austria. But also many customers in Germany and Switzerland as
well as in the international European region rely on the software solutions developed
by BMD."

https://www.bmd.com/en/about-bmd/cdompany-profile.html


Business recommendation:
------------------------
The vendor provides a software update which should be installed immediately.

SEC Consult highly recommends to perform a thorough security review of the BMD Web
product conducted by security professionals to identify and resolve potential
further security issues.


Vulnerability overview/description:
-----------------------------------
1) Stored Cross Site Scripting (Outdated software library)
BMDWeb 2.0 uses DOMPurify version 1.0.10 (released in Feb 19, 2019) for sanitizing
untrusted user input. This outdated version suffers from many vulnerabilities that allow
bypasses of the sanitization logic.

A few examples:
- https://github.com/cure53/DOMPurify/issues/482
- https://research.securitum.com/dompurify-bypass-using-mxss/
- https://research.securitum.com/mutation-xss-via-mathml-mutation-dompurify-2-0-17-bypass/
- https://portswigger.net/research/bypassing-dompurify-again-with-mutation-xss

An attacker can execute arbitrary JavaScript code in the context of the victim's BMD
session, thus perform all actions in BMD, exfiltrate information, etc.

Note for DOMPurify users:
DOMPurify should be updated regularly. The project provides a mailing list with the
latest security information.

Further information: https://github.com/cure53/DOMPurify#security-mailing-list

Additionally, input validation is another measure against Stored Cross Site Scripting.


Proof of concept:
-----------------
1) Stored Cross Site Scripting (Outdated software library)
The following XSS vector can be used in all kinds of BMD user input fields, e.g.
time recording comment, service entry comment, etc.

<math><mtext><table><mglyph><style><![CDATA[</style><img title="]]&gt;&lt;/mglyph&gt;&lt;img&Tab;src=1&Tab;onerror=alert(0)&gt;">

This JavaScript code will then automatically get executed when the site which contains
the payload is visited by the victim.


Vulnerable / tested versions:
-----------------------------
The vulnerability has been found in BMD 23.45.32 (Build 1004581) which was the
latest version at the time of discovery.


Vendor contact timeline:
------------------------
2021-02-22: Contacting vendor
2021-02-22: Conference call to discuss vulnerability.
2021-03-02: Vendor publishes patch.
2021-04-22: Coordinated release of security advisory.


Solution:
---------
Install BMD 24.01.21 or 24.02.11 or higher versions which are available to all customers
with support contract.


Workaround:
-----------
None


Advisory URL:
-------------
https://sec-consult.com/vulnerability-lab/

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SEC Consult Vulnerability Lab

SEC Consult, an Atos company
Europe | Asia | North America

About SEC Consult Vulnerability Lab
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult, an
Atos company. It ensures the continued knowledge gain of SEC Consult in the
field of network and application security to stay ahead of the attacker. The
SEC Consult Vulnerability Lab supports high-quality penetration testing and
the evaluation of new offensive and defensive technologies for our customers.
Hence our customers obtain the most current information about vulnerabilities
and valid recommendation about the risk profile of new technologies.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Interested to work with the experts of SEC Consult?
Send us your application https://sec-consult.com/career/

Interested in improving your cyber security with the experts of SEC Consult?
Contact our local offices https://sec-consult.com/contact/
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Mail: research at sec-consult dot com
Web: https://www.sec-consult.com
Blog: http://blog.sec-consult.com
Twitter: https://twitter.com/sec_consult

EOF Stefan Viehböck / @2021


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