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Vulnerability of Excel: use after free via XLSB

Synthesis of the vulnerability 

An attacker can invite the victim to open a malicious XLSB file, to force the usage of a freed memory area in Excel, in order to trigger a denial of service, and possibly to run code.
Vulnerable systems: Lync, Office, Access, Office Communicator, Excel, OneNote, Outlook, PowerPoint, Project, Publisher, MOSS, Visio, Word, Skype for Business.
Severity of this threat: 3/4.
Creation date: 15/12/2015.
Références of this weakness: 3104540, MS15-116, VIGILANCE-VUL-18524, ZDI-15-639.

Description of the vulnerability 

The Excel product supports binary files with the ".xlsb" extension.

However, if the file is malformed, Excel frees a memory area before reusing it.

An attacker can therefore invite the victim to open a malicious XLSB file, to force the usage of a freed memory area in Excel, in order to trigger a denial of service, and possibly to run code.
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This vulnerability alert impacts software or systems such as Lync, Office, Access, Office Communicator, Excel, OneNote, Outlook, PowerPoint, Project, Publisher, MOSS, Visio, Word, Skype for Business.

Our Vigil@nce team determined that the severity of this computer weakness alert is important.

The trust level is of type confirmed by the editor, with an origin of document.

An attacker with a expert ability can exploit this computer vulnerability.

Solutions for this threat 

Microsoft Office, Lync: patch.
A patch is indicated in information sources.
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