TippingPoint Zero Day Initiative

Microsoft ISA Server SOCKS4 Proxy Connection Leakage Vulnerability

ZDI-07-053: September 20th, 2007


Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 4085. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows remote attackers to extract IP addresses visited through the SOCKS4 Proxy on vulnerable ISA Server installations. Authentication is not required to exploit this vulnerability.

This specific flaw exists when an empty packet is sent to the SOCKS4. The server will return a packet containing the last IP address it proxied to.

Vendor Response

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

Disclosure Timeline

    2006-01-30 - Vulnerability reported to vendor
    2007-09-20 - Coordinated public release of advisory


This vulnerability was discovered by: