PT-2013-73: XML External Entities Resolution vulnerability in Microsoft Office Word

Vulnerable software

Microsoft Office Word
Version: 2007 SP3 and earlier; 2003 SP3 and earlier

Microsoft Office
Version: 2007 SP3 and earlier; 2003 SP3 and earlier

Microsoft Word Viewer
Version: 2007 SP3 and earlier

Link:
http://microsoft.com/

Severity level

Severity level: Medium
Impact: Internal Network Resources and File System Access, Denial of Service 
Access Vector: Remote

CVSS v2:
Base Score: 5.8
Vector: (AV:N/AC:M/Au:N/C:P/I:N/A:P)

CVE: CVE-2013-3160

Software description

Microsoft Office Word is a commercial word processor designed by Microsoft.

Vulnerability description

The specialists of the Positive Research center have detected an XML External Entities Resolution vulnerability in Microsoft Office Word and Word Viewer.

The vulnerability is possible due to unsafe parsing of XML external entities. If an attacker makes a victim open a specially crafted XML document, Microsoft Office Word installed on the victim's system will automatically send the contents of local or remote resource to the attacker's server provided that the use of the remote XSD was approved by the user. It also makes possible to conduct denial of service attacks.

How to fix

Use vendor's advisory:
http://technet.microsoft.com/en-us/security/bulletin/ms13-072

Advisory status

26.11.2012 - Vendor gets vulnerability details
10.09.2013 - Vendor releases fixed version and details 
09.10.2013 - Public disclosure

Credits

The vulnerability was detected by Timur Yunusov, Alexey Osipov and Ilya Karpov, Positive Research Center (Positive Technologies Company)

References

http://en.securitylab.ru/lab/PT-2013-73

Reports on the vulnerabilities previously discovered by Positive Research:

http://www.ptsecurity.com/research/advisory/
http://en.securitylab.ru/lab/

Threatscape
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