TippingPoint Zero Day Initiative

Microsoft Remote Desktop Client Arbitrary Code Execution Vulnerability

ZDI-09-057: August 11th, 2009


Affected Vendors

Affected Products

    Remote Desktop

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 8379. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows attackers to execute arbitrary code on vulnerable installations of Microsoft's Remote Desktop Client. Authentication is not required to exploit this vulnerability.

The specific flaw exists within mstscax.dll when parsing packets from an RDP server. A design flaw in the client allows a malicious RDP server to write to arbitrary memory inside the connecting processes memory space. By hosting a malicious RDP server, an attacker can execute arbitrary code on any client that attempts to connect to it. Privileges gained depend on which user is running the client.

Vendor Response

Microsoft has issued an update to correct this vulnerability. More details can be found at:

Disclosure Timeline

    2008-04-07 - Vulnerability reported to vendor
    2009-08-11 - Coordinated public release of advisory


This vulnerability was discovered by:
    wushi of team509 and the SureRun Security Team