ZDI-07-055: Microsoft Windows DCERPC Authentication Denial of Service Vulnerability Oct 10 2007 09:51PM
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ZDI-07-055: Microsoft Windows DCERPC Authentication Denial of Service



October 10, 2007

-- CVE ID:


-- Affected Vendor:


-- Affected Products:

Windows 2000 SP4

Windows XP SP2

Windows 2003 SP1

Windows Vista

-- TippingPoint(TM) IPS Customer Protection:

TippingPoint IPS customers have been protected against this

vulnerability since October 9, 2007 by Digital Vaccine protection

filter ID 5657. For further product information on the TippingPoint IPS:


-- Vulnerability Details:

This vulnerability allows remote attackers to crash systems with

vulnerable installations of the Microsoft Windows operating system.

Authentication is not required to exploit this vulnerability.

The specific flaw exists within the RPC runtime library rpcrt4.dll

during the parsing of RPC-level authentication messages. When parsing

packets with the authentication type of NTLMSSP and the authentication

level of PACKET, an invalid memory dereference can occur if the

verification trailer signature is initialized to 0 as opposed to the

standard NTLM signature. Successful exploitation crashes the RPC

service and subsequently the entire operating system.

-- Vendor Response:

Microsoft has issued an update to correct this vulnerability. More

details can be found at:


-- Disclosure Timeline:

2007.02.05 - Vulnerability reported to vendor

2007.10.09 - Digital Vaccine released to TippingPoint customers

2007.10.10 - Coordinated public release of advisory

-- Credit:

This vulnerability was discovered by Tenable Network Security.

-- 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:


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.

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