ZDI-06-038: Citrix MetaFrame IMA Management Module Remote Heap Overflow
http://www.zerodayinitiative.com/advisories/ZDI-06-038.html
November 9, 2006

-- CVE ID:
CVE-2006-5821

-- Affected Vendor:
Citrix

-- Affected Products:
Citrix MetaFrame XP 1.0
Citrix MetaFrame XP 2.0
Citrix MetaFrame Presentation Server 3.0
Citrix MetaFrame Presentation Server 4.0

-- TippingPoint(TM) IPS Customer Protection:
TippingPoint IPS customers have been protected against this
vulnerability since November 9, 2006 by Digital Vaccine protection
filter ID 4494. For further product information on the TippingPoint IPS:

    http://www.tippingpoint.com 

-- Vulnerability Details:
This vulnerability allows attackers to execute arbitrary code on
vulnerable installations of Citrix MetaFrame Presentation Server.
Authentication is not required to exploit this vulnerability.

The specific flaw exists within the routine IMA_SECURE_DecryptData1()
defined in ImaSystem.dll and is reachable through the Independant
Management Architecture (IMA) service (ImaSrv.exe) that listens on TCP
port 2512 or 2513. The encryption scheme used is reversible and relies
on several 32-bit fields indicating the size of the packet and the
offsets to the authentication strings. During the decryption of
authentication data an attacker can specify invalid sizes that result
in an exploitable heap corruption.

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

http://support.citrix.com/article/CTX111186

-- Disclosure Timeline:
2006.06.16 - Vulnerability reported to vendor
2006.11.09 - Digital Vaccine released to TippingPoint customers
2006.11.09 - Coordinated public release of advisory

-- Credit:
This vulnerability was discovered by Eric Detoisien and 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.