TippingPoint Zero Day Initiative
 

Microsoft Office Excel REPT Formula Parsing Remote Code Execution Vulnerability

ZDI-08-099: October 14th, 2008

CVE ID

Affected Vendors

Affected Products

TippingPoint™ IPS Customer Protection

TippingPoint IPS customers are protected against this vulnerability by Digital Vaccine protection filter ID 9914. For further product information on the TippingPoint IPS:

Vulnerability Details

This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Microsoft Office. 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 when parsing Microsoft Excel documents containing a malformed REPT formula embedded inside a cell. During evaluation of this cell Excel miscalculates the size of a static buffer and copies the result of the formula into it resulting in an exploitable condition. This can result in a remote compromise of the system under the credentials of the currently logged in user.

Vendor Response

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

Disclosure Timeline

    2008-06-25 - Vulnerability reported to vendor
    2008-10-14 - Coordinated public release of advisory

Credit

This vulnerability was discovered by:
    CHkr_D591