SEC Consult Vulnerability Lab Security Advisory < 20200407-0 >
=======================================================================
              title: Multiple XSS vulnerabilities
            product: TAO Open Source Assessment Platform
 vulnerable version: 3.3.0 RC2
      fixed version: -
         CVE number: -
             impact: medium
           homepage: https://www.taotesting.com/product/community/
              found: 2019-09-16
                 by: David Haintz
                     SEC Consult Vulnerability Lab

                     An integrated part of SEC Consult
                     Europe | Asia | North America

                     https://www.sec-consult.com

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Vendor description:
-------------------
"The Next Generation Open Source Assessment Solution -
Say goodbye to technical complexity and yet another IT project. Say hello to an
all-in-one assessment solution. Easily tap into the power of open source, single
sign-on and LTI. Open source means open possibilities so you can benefit from
the ideas of the expert assessment community."

Source: https://www.taotesting.com/product/


Business recommendation:
------------------------
The vendor did not respond to our communication attempts, hence no patch is
available.

An in-depth security analysis performed by security professionals is
highly advised, as the software may be affected from further security
issues.


Vulnerability overview/description:
-----------------------------------
1) Multiple XSS vulnerabilities
Several pages lack input validation within the URL that is output into the
action attribute of a form. An attacker can break out of the string
and add custom JavaScript events to several forms. Additionally, the error
page also lacks filtering user input / output.


Proof of concept:
-----------------
1) Multiple XSS vulnerabilities
a) XSS in URL for form action attributes

If a victim accesses the following link and enters their credentials, an alert
shows the entered password:

[ removed PoC from advisory ]

Since chars like " or < and > are filtered in this case, a string had to be built
by using char codes and JavaScript's String.fromCharCode(). The same pattern
works for many other paths too. Following additional paths were also found to be
vulnerable:

[ removed PoC from advisory ]


b) XSS in error page
The internal error page also lacks input/output validation. The following URL
generates a website opening a message box showing the current location without
any filtering:

[ removed PoC from advisory ]


Vulnerable / tested versions:
-----------------------------
The following version has been tested, which was the most recent one at the time
of the test:

* 3.3.0 RC2


Vendor contact timeline:
------------------------
2019-09-17: Contacting vendor through https://www.taotesting.com/contact-us/
2019-10-08: Contacting vendor again through https://www.taotesting.com/contact-us/
2020-03-19: Checked whether newer version exists; contacting vendor again through
            contact form and support contact email address.
            Got sales auto-response which automatically booked an online
            meeting with a "Business Development" person. Also automatically got
            added to a newsletter which we did not agree in the contact form.
            Contacted "Business Development" person via email directly. No response.
2020-03-20: Sent email again, asking for security contact
2020-03-23: Sent email again to sales@taotesting.com and "Business Development"
            person; no response
2020-04-07: Release of security advisory


Solution:
---------
The vendor did not respond to our communication attempts, hence no patch is
available.


Workaround:
-----------
Don't use the product or implement additional measures such as a WAF until the
vendor fixes the security issues.


Advisory URL:
-------------
https://www.sec-consult.com/en/vulnerability-lab/advisories/index.html


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

SEC Consult Vulnerability Lab

SEC Consult
Europe | Asia | North America

About SEC Consult Vulnerability Lab
The SEC Consult Vulnerability Lab is an integrated part of SEC Consult. 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.

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EOF @D. Haintz, J. Greil / 2020