TippingPoint Zero Day Initiative

Microsoft Windows EngLockSurface Time-Of-Check Time-Of-Use Race Condition Information Disclosure Vulnerability

ZDI-17-917: November 20th, 2017


CVSS Score

Affected Vendors

Affected Products


Vulnerability Details

This vulnerability allows local attackers to disclose sensitive information on vulnerable installations of Microsoft Windows. An attacker must first obtain the ability to execute low-privileged code on the target system in order to exploit this vulnerability.

The specific flaw exists within the implementation of the EngLockSurface API. Performing a memory write at an unexpected time during the execution of EngLockSurface can cause the kernel to read from an improper address. An attacker can leverage this in conjunction with other vulnerabilities to execute arbitrary code in the context of SYSTEM.

Vendor Response

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

Disclosure Timeline

    2017-09-01 - Vulnerability reported to vendor
    2017-11-20 - Coordinated public release of advisory


This vulnerability was discovered by:
    Marcin Wiazowski