Vulnerability identifier: #VU2946

Vulnerability risk: High

CVSSv3.1: 9.2 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2011-0978

CWE-ID: CWE-121

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Microsoft Office
Client/Desktop applications / Office applications
Microsoft Excel
Client/Desktop applications / Office applications
Microsoft Office for Mac
Client/Desktop applications / Office applications

Vendor: Microsoft

Description
The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The weakness exists due to array indexing error when validating record information. A remote attacker can create a specially crafted Excel file, trick the victim into opening it, trigger stack-based buffer overlow and execute arbitrary code with privileges of the current user.

Successful exploitation of the vulnerability results in arbitrary code execution on the vulnerable system.

Mitigation
Install update from vendor's website:

Microsoft Excel 2002 Service Pack 3:
https://www.microsoft.com/downloads/details.aspx?familyid=db2c5cfe-588c-4646-b86a-3fb8248f7af4
http://go.microsoft.com/fwlink/?LinkId=200529
Microsoft Excel 2003 Service Pack 3:
https://www.microsoft.com/downloads/details.aspx?familyid=916a076d-d754-4092-b23d-c8826db7e397
http://go.microsoft.com/fwlink/?LinkId=200529
Microsoft Excel 2007 Service Pack 2:
https://www.microsoft.com/downloads/details.aspx?familyid=5ae34fe0-03bd-48a9-a7ac-de8f7b1aff90
http://go.microsoft.com/fwlink/?LinkId=200529
Microsoft Office 2004 for Mac:
https://www.microsoft.com/downloads/details.aspx?FamilyID=f756d836-6ab2-4adb-9dee-6cb523d7c1f5
Microsoft Excel Viewer Service Pack 2:
https://www.microsoft.com/downloads/details.aspx?familyid=2d75786a-2368-4ef2-970b-fa2e57d63ca9
http://go.microsoft.com/fwlink/?LinkId=200529
Microsoft Office Compatibility Pack for Word, Excel, and PowerPoint 2007 File Formats Service Pack 2:
https://www.microsoft.com/downloads/details.aspx?familyid=946cc611-4d75-4728-b9d3-1c8b557b02c2
http://go.microsoft.com/fwlink/?LinkId=200529

Vulnerable software versions

Microsoft Office: 2007

Microsoft Excel:

Microsoft Office for Mac: 2004

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External links
http://technet.microsoft.com/en-us/library/security/ms11-021.aspx

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.