Rule Category

FILE-OFFICE -- Snort detected traffic targeting vulnerabilities in files belonging to the Microsoft Office suite of software (Excel, PowerPoint, Word, Visio, Access, Outlook, etc.).

Alert Message

FILE-OFFICE Microsoft Office Excel fileVersion use-after-free attempt

Rule Explanation

Use-after-free vulnerability in Microsoft Excel 2007 SP3, Excel 2010 SP2, Excel 2013 SP1, Excel 2013 RT SP1, Excel 2016, Excel for Mac 2011, Excel 2016 for Mac, Excel Viewer, Office Compatibility Pack SP3, and Excel Services on SharePoint Server 2007 SP3, 2010 SP2, and 2013 SP1 allows remote attackers to execute arbitrary code via a long fileVersion element in an Office document, aka "Microsoft Office Memory Corruption Vulnerability."

What To Look For

This rule triggers on a Microsoft Excel file containing a malicious fileVersion element.

Known Usage

No public information

False Positives

No known false positives

Contributors

Talos research team

MITRE ATT&CK Framework

Tactic: Execution

Technique: Exploitation for Client Execution

For reference, see the MITRE ATT&CK vulnerability types here: https://attack.mitre.org

CVE

Additional Links

Rule Vulnerability

Memory Corruption

Memory Corruption is any vulnerability that allows the modification of the content of memory locations in a way not intended by the developer. Memory corruption results are inconsistent; they could lead to fatal errors and system crashes or data leakage; some have no effect at all.

CVE Additional Information

CVE-2015-2558
Use-after-free vulnerability in Microsoft Excel 2007 SP3, Excel 2010 SP2, Excel 2013 SP1, Excel 2013 RT SP1, Excel 2016, Excel for Mac 2011, Excel 2016 for Mac, Excel Viewer, Office Compatibility Pack SP3, and Excel Services on SharePoint Server 2007 SP3, 2010 SP2, and 2013 SP1 allows remote attackers to execute arbitrary code via a long fileVersion element in an Office document, aka "Microsoft Office Memory Corruption Vulnerability."
Details
SeverityHIGH Base Score9.3
Impact Score10.0 Exploit Score8.6
Confidentiality ImpactCOMPLETE Integrity ImpactCOMPLETE
Availability ImpactCOMPLETE Access Vector
AuthenticationNONE Ease of Access