Zero-Day Advisory

Fortinet Discovers Microsoft SharePoint Cross-Site Scripting Vulnerability

Summary

Fortinet's FortiGuard Labs has discovered a Cross-Site Scripting (XSS) vulnerability in Microsoft SharePoint.
SharePoint is a web application platform in the Microsoft Office server suite. SharePoint combines various functions. SharePoint servers have traditionally been deployed for internal use in mid-size businesses and large departments alongside Microsoft Exchange, Skype for Business, and Office Web Application Server.
XSS vulnerability has been discovered in SharePoint 2013. The vulnerability is caused due to insufficiently sanitizing user-supplied input in a number of input fields like notes, keywords and comments. It allows remote attackers to launch XSS attacks. The attackers can exploit this vulnerability to inject malicious JavaScript code to potentially issue SharePoint commands in the context of another authenticated user.

Solutions

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

MS.SharePoint.App.Links.Notes.XSS
Released Aug 20, 2015
Users should apply the solution provided by Microsoft.

References

• https://technet.microsoft.com/library/security/ms15-099
• CVE-2015-2522

Acknowledgement

This vulnerability was discovered by Zhouyuan Yang 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.