What you need to know about new zero day that hits most supported Windows versions

Microsoft issued a security advisory this week with details of a zero day vulnerability that affects every supported version of the Windows operating system with the exception of Windows Server 2003. The flaw is very similar to the OLE vulnerability patched earlier this month, which was linked to the Sandworm cyber espionage campaign.

Like the vulnerability in MS14-060, this new flaw is exploited through the use of a malicious Microsoft Office file that contains an OLE object. If successfully exploited, the flaw could allow an attacker to execute malicious code remotely on the vulnerable system, with the rights and privileges of the currently logged in user.

McAfee is credited with helping to identify the new vulnerability while investigating Sandworm. A McAfee blog post explains, "During our investigation, we found that the Microsoft's official patch is not robust enough. In other words, attackers might still be able to exploit the vulnerability even after the patch is applied. Users who have installed the official patch are still at risk."

Microsoft details some mitigating factors in the security advisory. UAC (User Account Control) is enabled by default in Windows, and will display a consent prompt that should alert users that something suspicious is going on. The exploit only gives an attacker the same rights as the current user, so logging in as a Standard user as opposed to an Administrator limits the potential impact as well.

Lamar Bailey, director of security research for Tripwire, suggests this zero day vulnerability is not really a serious threat. "Users should know better than open email attachments from unknown sources or download documents from random Internet sites." Bailey added, "Users should use caution when opening attachments, even if they appear to come from a legitimate source and avoid downloading files from Internet websites."

"More than ever, people need to verify the source before clicking or downloading documents," agrees TK Keanini, CTO of Lancope. "At some point, users will need to demand a higher level of authenticity. The technology is here, it is just not yet socially practiced to doubt that a person is who they say they are. The threshold of pain is still not yet high enough to change human behaviors."

Morey Haber, a senior director of program management at BeyondTrust, provides some basic guidance for mitigating this threat. "Do not open files from untrusted sources or unknown email addresses, apply the CVE configuration file for EMET if it is configured within your environment, and most importantly ensure users are not executing applications as an administrator."

"The last mitigation strategy is the most important since it has the most benefit for any attack of this nature," stressed Haber. "If the host is compromised with a zero day like this, the potential exploit is limited to standard user permissions and not system admin. Its ability to alter system settings and infect other assets is crippled and the problem is contained until the system can be remediated. Reduction in user privileges is one of the best recourses to manage an infection from spreading and the loss of system data."

Microsoft is continuing its investigation of the scope and impact of this threat, and will most likely issue an update to patch this vulnerability at some point in the near future. In the meantime, you should follow the advice from security experts shared in this article. For additional protection, you can also apply the Microsoft Fix It solution. The Fix It solution only addresses Microsoft PowerPoint, though (with the exception of 64-bit PowerPoint on x64-based versions of Windows 8 or Windows 8.1), so you should still use caution and not consider the Fix It a comprehensive fix for this flaw.