full-disclosure - n.runs-SA-2012.003

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Date: Fri, 2 Nov 2012 16:44:47 +0100
From: <security@...ns.com>
To: <full-disclosure@...ts.grok.org.uk>,
	<bugtraq@...urityfocus.com>
Cc: cve@...re.org, soc@...cert.gov, vuln@...unia.com, cert@...t.org
Subject: n.runs-SA-2012.003 - SPLUNK DoS HashDOS

n.runs AG
http://www.nruns.com/                              security(at)nruns.com
n.runs-SA-2012.003                                           02-Nov-2012
________________________________________________________________________
Vendors:            Splunk Inc., http://www.splunk.com
Product:            Splunk 4.3.x (+ possibly earlier versions)
Vulnerability:      Unauth. remote denial of service against splunkweb
Tracking IDs:       CVE-2012-1150
                    SPL-53249
___________________________________________________________________________
Vendor communication:
2012/09/03 Reported the issue via Splunk's website
2012/09/04 Splunk responds and assigns tracking ID, plans fix for 5.0.
                       Replacing the Python version in a maintenance release
(4.3.x)
	       was considered too risky.
2012/10/25 Splunk informs us that 5.0 will be available on November 1st.
2012/10/29 Splunk 5.0 is released.
___________________________________________________________________________
Overview:

Splunkweb uses Python 2.7.2, which suffers from a vulnerability which allows
an
attacker to produce hash collisions for the hash table string hashing
function.
This leads to an O(n^2) complexity when inserting n keys (see
http://bugs.python.org/issue13703).

Description:

An attacker can abuse this vulnerability by sending a POST request to
Splunkweb
(for example to the login form endpoint) with colliding keys. Even a
moderate
amount of POST data leads to a 100% CPU usage for the splunkweb process.

Impact:

Denial of service (CPU exhaustion) against the Splunk server.

Fixes:

This issue has been fixed in Splunk 5.0 by updating the Python version
to 2.7.3 and enabling hash randomization.  

________________________________________________________________________
Credits:
Alexander Klink, n.runs AG (discovery)
________________________________________________________________________
References:
This advisory and upcoming advisories:
http://www.nruns.com/security_advisory.php
________________________________________________________________________
About n.runs:
n.runs AG is a vendor-independent consulting company specialising in the
areas of: IT Infrastructure, IT Security and IT Business Consulting.

Copyright Notice:
Unaltered electronic reproduction of this advisory is permitted. For all
other reproduction or publication, in printing or otherwise, contact
security@...ns.com for permission. Use of the advisory constitutes
acceptance for use in an as is condition. All warranties are excluded.
In no event shall n.runs be liable for any damages whatsoever including
direct, indirect, incidental, consequential, loss of business profits or
special damages, even if n.runs has been advised of the possibility of such
damages.
Copyright 2012 n.runs AG. All rights reserved. Terms of use apply.

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