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 ======================================================================= title: Stored Cross Site Scripting (Outdated software library) product: BMD BMDWeb 2.0 vulnerable version: BMD versions prior to 24.01.21 fixed version: 24.01.21 and 24.02.11 or higher CVE number: -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 Vulnerability overview/description: ----------------------------------- 1) Stored Cross Site Scripting (Outdated software library) BMDWeb 2.0 uses DOMPurify version 1.0.10 (released in Feb 19, 2019) for sanitizing untrusted user input. This outdated version suffers from many vulnerabilities that allow bypasses of the sanitization logic.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 Proof of concept: ----------------- 1) Stored Cross Site Scripting (Outdated software library) The following XSS vector can be used in all kinds of BMD user input fields, e.g. time recording comment, service entry comment, etc.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