ZDI-07-006: Citrix Metaframe Presentation Server Print Provider Buffer Overflow Vulnerability

ZDI-07-006: Citrix Metaframe Presentation Server Print Provider Buffer
Overflow Vulnerability
http://www.zerodayinitiative.com/advisories/ZDI-07-006.html
January 24, 2007

– CVE ID:
CVE-2007-0444

– Affected Vendor:
Citrix

– Affected Products:
Citrix Presentation Server 4.0
Citrix MetaFrame Presentation Server 3.0
Citrix MetaFrame XP 1.0

– TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability since July 7, 2005 by the pre-existing Digital
Vaccine protection filter ID 3583. For further product information
on the TippingPoint IPS:

http://www.tippingpoint.com 

– Vulnerability Details:
This vulnerability allows remote attackers to execute arbitrary code on
systems with vulnerable installations of Citrix Presentation Server,
Metaframe Presentation Server or MetaFrame XP. Authentication is not
required to exploit this vulnerability.

The specific flaw exists in a print provider installed by the
Presentation Server. The cpprov.dll library doesn't properly handle
certain invalid calls to the EnumPrintersW() and OpenPrinter()
functions. For example, passing a string of 130 or more characters in
the first argument to the OpenPrinter() function results in a
stack-based buffer overflow and can be leveraged to execute code in the
context of the Spooler service, which runs as the privileged LocalSystem
account.

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

http://support.citrix.com/article/CTX111686

– Disclosure Timeline:
2005.07.07 - Pre-exiting Digital Vaccine released to TippingPoint
customers
2006.10.02 - Vulnerability reported to vendor
2007.01.24 - Coordinated public release of advisory

– Credit:
This vulnerability was discovered by an anonymous researcher.

– About the Zero Day Initiative (ZDI):
Established by TippingPoint, a division of 3Com, The Zero Day Initiative
(ZDI) represents a best-of-breed model for rewarding security
researchers for responsibly disclosing discovered vulnerabilities.

Researchers interested in getting paid for their security research
through the ZDI can find more information and sign-up at:

http://www.zerodayinitiative.com

The ZDI is unique in how the acquired vulnerability information is used.
3Com does not re-sell the vulnerability details or any exploit code.
Instead, upon notifying the affected product vendor, 3Com provides its
customers with zero day protection through its intrusion prevention
technology. Explicit details regarding the specifics of the
vulnerability are not exposed to any parties until an official vendor
patch is publicly available. Furthermore, with the altruistic aim of
helping to secure a broader user base, 3Com provides this vulnerability
information confidentially to security vendors (including competitors)
who have a vulnerability protection or mitigation product.