rexx Recruitment Cross-Site Scripting in User Registration
Product: rexx Recruitment
Affected Versions: Releases prior to those fixed on 2014-01-15
Fixed Versions: R6.1 and R7 with fixes from 2014-01-15
Vulnerability Type: Cross-Site Scripting
Security Risk: high
Vendor URL: http://www.rexx-systems.com
Vendor Status: fixed version released
Advisory URL: https://www.redteam-pentesting.de/advisories/rt-sa-2014-002
Advisory Status: published
CVE URL: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-1224
"rexx Recruitment supports around 3 million application processes each year (data from 2011). This stems from experience in applicant management: from company recruitment in small and medium-sized
enterprises and international companies, through to specialised personnel service providers.
The rexx Recruitment software supports paper, online and email applications. All information about and communication with the applicant at a glance in the digital applicant file!"
(from rexx systems' homepage)
The rexx Recruitment software includes a user registration where job applicants who want to stay informed about new vacancies can register. The registration site is usually available at the path "/reg", for example at a URL like the following:
The website asks for some mandatory data like name and surname as well as postal and email addresses. If a mandatory entry is missing when submitting the data, the website will present the registration site again to the user, with those input fields pre-populated with the data that was already filled in and error messages for the missing input fields. The pre-populated "first name" field with the name "redteam" would for example look as follows in the HTML source code:
<input type="text" style="" id="fname" name="fname" value="redteam" title="" />
If it is now tried to embed control characters like an opening angle bracket in the name, the system filters the input by removing everything after the bracket. The value "red<team" would for example be shortened to "red".
The application also removes known event handlers from user input, so the input
redteam" onmouseover="alert('RedTeam Pentesting')
is reduced to
redteam" "alert('RedTeam Pentesting')
redteam" oninput="alert('RedTeam Pentesting')
It is also possible by simply adding the even handler two times to make the application only remove one instance of the string. The input
redteam" onfocusonfocus=="alert('RedTeam Pentesting')" autofocus="autofocus
will be changed to the desired string
redteam" onfocus="alert('RedTeam Pentesting')" autofocus="autofocus
and therefore the input field will look like this:
Proof of Concept
The following URL adds a new "onfocus" event handler to the "fname" input field that gets executed as soon as the website is loaded due to the "autofocus" attribute:
If possible, disable user registration and disallow access to the registration website, e.g. by blocking access in the web server.
Update to versions R6.1 or R7 with the fixes from 2014-01-15 included.
2013-12-04 Vulnerability identified
2013-12-10 Customer approved disclosure to vendor
2013-12-13 Vendor notified
2014-01-15 Vendor released fixed version
2014-02-11 CVE number requested and assigned
2014-03-27 Advisory released
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