ZDI-11-090: Novell Netware RPC XNFS xdrDecodeString Remote Code Execution Vulnerability

http://www.zerodayinitiative.com/advisories/ZDI-11-090

February 18, 2011

-- CVE ID:
CVE-2010-4227

-- CVSS:
10, (AV:N/AC:L/Au:N/C:C/I:C/A:C)

-- Affected Vendors:
Novell

-- Affected Products:
Novell Netware

-- TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability by Digital Vaccine protection filter ID 10874. 
For further product information on the TippingPoint IPS, visit:

    http://www.tippingpoint.com

-- Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code on
vulnerable installations of Novell Netware. Authentication is not
required to exploit this vulnerability. 

The flaw exists within the XNFS.NLM component which listens by default
on UDP port 1234. When handling the an NFS RPC request the
xdrDecodeString function uses a user supplied length value to null
terminate a string. This value can be signed allowing the NULL byte to
be written at an arbitrary address. A remote attacker can exploit this
vulnerability to execute arbitrary code under the context of the system.

-- Vendor Response:
Novell has issued an update to correct this vulnerability. More
details can be found at:

http://download.novell.com/Download?buildid=1z3z-OsVCiE~

-- Disclosure Timeline:
2010-08-25 - Vulnerability reported to vendor
2011-02-18 - Coordinated public release of advisory

-- Credit:
This vulnerability was discovered by:
    * Francis Provencher for Protek Researchh Lab's

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