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[Full-disclosure] Microsoft SQL Server 2005 sp_replwritetovarbin memory overwrite (update to SEC Consult SA-20081209)

From: Bernhard Mueller (researchsec-consult.com)
Date: Wed Dec 10 2008 - 06:45:02 CST


Update to SEC Consult Security Advisory 20081210-0
(Microsoft SQL Server sp_replwritetovarbin limited memory overwrite
vulnerability)
===================================================================

Summary:
------------

By calling the extended stored procedure sp_replwritetovarbin, an
attacker can write limited values to arbitrary locations in process
memory. This vulnerability has been described in a prior security
advisory for MS SQL Server 2000:

http://www.securityfocus.com/archive/1/499042

Moreno Zilli of Swisscom has reported that MS SQL Server 2005 is
vulnerable to the same attack. This has been confirmed in a lab test
conducted by SEC Consult.
Our public security advisory has been updated accordingly:

http://www.sec-consult.com/files/20081209_mssql-sp_replwritetovarbin_memwrite.txt

Workaround:
-----------

Remove the sp_replwriterovarbin extended stored procedure. Run the
following as an administrator:

execute dbo.sp_dropextendedproc 'sp_replwritetovarbin'

See also:

"Removing an Extended Stored Procedure from SQL Server"
http://msdn.microsoft.com/en-us/library/aa215995(SQL.80).aspx

Patch:
------

According to an email received by Microsoft in September, a fix for this
vulnerability has been completed.
The release schedule for this fix is currently unknown.

Vendor timeline:
---------------
Vendor notified: 2008-04-17
Vendor response: 2008-04-17
Last response from Microsoft: 09-29-2008
Request for update status 1: 10-14-2008
Request for update status 2: 10-29-2008
Request for update status 3: 11-12-2008
Request for update status 4
and prenotification about advisory release date: 11-28-2008
Public release: 12-09-2008
Update (added MS-SQL 2005): 12-10-2008

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EOF Bernhard Mueller / 2008

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