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n.runs-SA-2012.003 - SPLUNK DoS HashDOS
From: <security () nruns com>
Date: Fri, 2 Nov 2012 16:44:47 +0100

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
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
               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.

Splunkweb uses Python 2.7.2, which suffers from a vulnerability which allows
attacker to produce hash collisions for the hash table string hashing
This leads to an O(n^2) complexity when inserting n keys (see


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


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


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

Alexander Klink, n.runs AG (discovery)
This advisory and upcoming advisories:
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:
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other reproduction or publication, in printing or otherwise, contact
security () nruns com for permission. Use of the advisory constitutes
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In no event shall n.runs be liable for any damages whatsoever including
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special damages, even if n.runs has been advised of the possibility of such
Copyright 2012 n.runs AG. All rights reserved. Terms of use apply.

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