A cross-site scripting and spoofing vulnerability affects Microsoft Windows SharePoint Services and SharePoint Team Services. A remote attacker may carry out a cross-site scripting attack to execute arbitrary HTML and script code in a user's browser. It is also possible to poison Web browser and intermediate proxy server caches by placing spoofed content in the caches.
Block external access at the network boundary, unless external parties require service.
Access to the affected computer providing SharePoint Services may be blocked at the network perimeter. Only allow trusted computers and networks to have access to resources.
Run all software as a nonprivileged user with minimal access rights.
It may also be possible for attackers to more successfully exploit client flaws in the browser through cross-site scripting vulnerabilities. When possible, run client software (especially programs such as IM clients, Web browsers and MUAs) as regular user accounts with limited access to system resources. This may limit the immediate consequences of client-side vulnerabilities.
Do not follow links provided by unknown or untrusted sources.
Users should avoid Web sites of questionable integrity and not follow links supplied by unknown or untrusted sources.
Set web browser security to disable the execution of script code or active content.
As the exploitation of this issue allows the execution of malicious script code in Web clients, it may be possible to prevent successful exploitation by disabling script code and active content support within a client browser. It should be noted that this mitigation tactic might adversely affect Websites that rely on the execution of browser based script code.
Microsoft has released updates to address this vulnerability on supported platforms.