Zero-Day Advisory

Fortinet Discovers Microsoft Office Word Use After Free Vulnerability

Summary

Fortinet's FortiGuard Labs has discovered a use after free vulnerability in Microsoft Office Word.
Microsoft Office is an office suite of applications, servers and services. It was first announced by Microsoft in 1988. The first version of Office contained Microsoft Word, Microsoft Excel and Microsoft PowerPoint. Over the years, Office applications have grown substantially closer with shared features such as a common spell checker, OLE data integration and Visual Basic for Applications scripting language. Microsoft also positions Office as a development platform for line-of-business software under the Office Business Applications brand.
A use after free vulnerability has been discovered in Microsoft Office Word. The vulnerability exists due to an error while the vulnerable software attempts to open a specially crafted Microsoft Word file. It could lead to remote code execution.

Solutions

FortiGuard Labs released the following FortiGate IPS signature which covers this specific vulnerability:

MS.Office.Word.Use.After.Free
Released Oct 05, 2015
Users should apply the solution provided by Microsoft.

Additional Information

According to Microsoft, this vulnerability discovered by Fortinet is associated with the vulnerability CVE-2015-1683, which was ever patched in MS15-046 on May 12, June 9 in 2015. However, those patches are incomplete. So Microsoft re-released a new patch to comprehensively fix the issues associated with CVE-2015-1683 on October 13.

References

• https://technet.microsoft.com/library/security/MS15-046
• https://support.microsoft.com/en-us/kb/3085544
• CVE-2015-1683

Acknowledgement

This vulnerability was discovered by Kai Lu of Fortinet's FortiGuard Labs.

IPS Subscription

Fortinet customers who subscribe to Fortinet's intrusion prevention (IPS) service should be protected against this vulnerability with the appropriate configuration parameters in place. Fortinet's IPS service is one component of FortiGuard Subscription Services, which also offer comprehensive solutions such as antivirus, Web content filtering and antispam capabilities. These services enable protection against threats on both application and network layers. FortiGuard Services are continuously updated by FortiGuard Labs, which enables Fortinet to deliver a combination of multi-layered security intelligence and true zero-day protection from new and emerging threats. These updates are delivered to all FortiGate, FortiMail and FortiClient products. Fortinet strictly follows responsible disclosure guidelines to ensure optimum protection during a threat's lifecycle.