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Re: CVE Request -- openvas-scanner -- Insecure temporary file use by generation of an OVAL system characteristics document, when ovaldi support enabled
From: Tim Brown <timb () openvas org>
Date: Wed, 7 Sep 2011 13:57:05 +0100

On Wednesday 07 Sep 2011 13:13:45 Jan Lieskovsky wrote:
Hello Josh, Steve, vendors,

   it was reported that the scanner module for the Open Vulnerability
Assessment System (OpenVAS) used insecure way for creation of a
temporary file, when generating OVAL system characteristics document
from the knowledge base data available, with the ovaldi integrated tool
enabled. A local attacker could use this flaw to conduct symlink
attacks to overwrite arbitrary files on the system, accessible with the
privileges of the user running the SLAD daemon and / or the ovaldi OVAL
interpreter.


Whilst having a look at the code with regard to the recently reported f-d 
issue with OpenVAS, the handling of sc-out.xml in the very same function also 
looks insecure.  It also doesn't appear to care about races either and I'm 
also curious as to whether you can control the contents at all (think attacks 
against the ovaldi XML parser).  I would suggest that this code needs properly 
auditing or removing.

Unfortunately the interaction with sc-out.xml happens before privileges are 
dropped so the malicious activitity occurs as the openvas-scanner user 
(normally root) rather than nobody as in the case of results.xml - The call to 
unlink referenced in the f-d email is actually a misnomer as it will actually 
only delete the file from /tmp and not whatever it may or may not have pointed 
to and the actual writing to the newly race created symlink actually happens 
within the ovaldi binary which is spawned as nobody AFAIK.

Josh/oss-security folk, can I get a CVE for both bugs please.  Will we need to 
split out the two race conditions as separate CVE?  The OpenVAS advisory will 
cover both the originally reported nobody case as well as the root case 
referenced above.

Tim
-- 
Tim Brown
<mailto:timb () openvas org>
<http://www.openvas.org/>

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