TAO Open Source Assessment Platform 3.3.0 RC2 Cross Site Scripting

TAO Open Source Assessment Platform version 3.3.0 RC2 suffers from multiple cross site scripting vulnerabilities.

MD5 | 5b0bae6c1d43d5e3be93527c5f6ec745

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

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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

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

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

[ 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 [email protected] and "Business Development"
person; no response
2020-04-07: Release of security advisory

The vendor did not respond to our communication attempts, hence no patch is

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

Advisory URL:


SEC Consult Vulnerability Lab

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Europe | Asia | North America

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EOF @D. Haintz, J. Greil / 2020

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