Microsoft Office CTaskSymbol Use-After-Free Vulnerability

Product Microsoft Office
Severity High
CVE Reference CVE-2015-1642
Type CTaskSymbol Use-After-Free Vulnerability

An use-after-free vulnerability (CVE-2015-1642) was discovered as the affected application improperly handles the CTaskSymbol COM object in memory while parsing a crafted Office file. If persuaded to open the crafted Office file, a successful exploitation would allow an attacker to run arbitrary code in the context of the victim.

The advisory can be downloaded here.

Description

Microsoft Office is a suite of desktop applications consisting of Word, Powerpoint, Excel, Outlook and various other productivity applications. The applications are affected by a use-after-free vulnerability while parsing a specially crafted Office file as a result of the application loading the CTaskSymbolCOM object in memory.

Impact

If persuaded to open the crafted Office file, a successful exploitation would allow an attacker to run arbitrary code in the context of the target application.

Cause

The vulnerability exists because Microsoft Office incorrectly dereferences the CTaskSymbol object after it is freed.

Interim Workaround

Avoid opening Office files from untrusted sources or view them in Protected-View mode.

Solution

Users should apply MS15-081 updates from Microsoft.

Technical Details

Refer to attached detailed advisory above.

Detailed Timeline

Date Summary
27/02/2015 MWR Labs reported issue with technical details and POC
28/02/2015 Microsoft acknowledge receipt and start investigation of issue
02/04/2015 Microsoft replied that issue is assigned CVE-2015-1642
11/08/2015 Microsoft released patch as part of MS15-081
17/08/2015 MWR Labs released advisory