TippingPoint Zero Day Initiative

Microsoft Office Excel Binary Worksheet Uninitialized Pointer Remote Code Execution Vulnerability

ZDI-15-543: November 10th, 2015


CVSS Score

Affected Vendors

Affected Products

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Microsoft Office Excel. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.

The specific flaw exists within the handling of binary (.xlsb) Excel files. By providing a malformed .xlsb file, an attacker can cause the target location for a branch to be read from uninitialized memory. An attacker could leverage this to execute arbitrary code under the context of the Excel process.

Vendor Response

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

Disclosure Timeline

    2015-08-03 - Vulnerability reported to vendor
    2015-11-10 - Coordinated public release of advisory


This vulnerability was discovered by:
    Steven Seeley of Source Incite