Joomla core <= 3.1.5 reflected XSS vulnerability

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• Original release date: August 05, 2013
• Discovered by: Emilio Pinna (Application Security Analyst at Abinsula)
• Contact: (emilio (dot) pinn (at) gmail (dot) com)
• Severity: 4.3/10 (Base CVSS Score)
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VULNERABILITY

Joomla core package <= 3.1.5 includes a PHP script that suffers from
reflected XSS vulnerability that allows to inject HTML and malicious
scripts that can access any cookies, session tokens, or other
sensitive information retained by your browser and used with that
site.

Joomla is one of the most installed CMS with dozens of millions of
installations.

DESCRIPTION

Affected file libraries/idna_convert/example.php has different injection points:

• Unsanitized lang parameter in line 24
• Unsanitized file name printing on lines 112 and 119

PROOF OF CONCEPT

http://localhost/joomla/libraries/idna_convert/example.php?lang=&quot;&gt;&lt;script&gt;alert&#40;document.cookie&#41;;&lt;/script&gt;&lt;!--

BUSINESS IMPACT

As usual, attackers can exploit these weaknesses to execute arbitrary
HTML and script code in a user's browser session that visits the
malicious crafted url.

SYSTEMS AFFECTED

Joomla-CMS <= 3.1.5

SOLUTION

Fixed removing the vulnerable example file on git with commit
c00c033d33d901e1ca6be9061a44e55acd041b1f

REFERENCES

http://disse.cting.org/2013/08/05/joomla-core-3_1_5_reflected-xss-vulnerability/
https://github.com/joomla/joomla-cms/issues/1658

CREDITS

Emilio Pinna (emilio (dot) pinn (at) gmail (dot) com)

DISCLOSURE TIMELINE

August 4, 2013: Opened a ticket describing the bug by Adam Willard.
August 5, 2013: Fixed by Michael Babker.
August 5, 2013: Vulnerability disclosed by Emilio Pinna.

LEGAL NOTICES

The information contained within this advisory is supplied "as-is"
with no warranties or guarantees of fitness of use or otherwise.