EMET 4.0: Adding a Layer to the Security Onion

BeyondTrust Research Team, June 19th, 2013

With the release of the EMET 4.0 beta back in April, it’s no surprise that there has been a lot of buzz lately around Microsoft’s Enhanced Mitigation Experience Toolkit (EMET). Now, after some delay, the beta testing is over and the brand new, and very shiny, EMET v4 has been released.

The latest version of EMET introduces several features that address many of the techniques used in high profile attacks over the last few years. Features such as “Certificate Trust” allow users to configure a custom set of rules for implementing Certificate Pinning for various SSL certificates. This helps prevents man-in-the-middle (MitM) attacks that take advantage of the shortcomings of the SSL, which have gained quite a bit of attention in the past few years, with incidents such as the DigiNotar fiasco.

Additionally, several memory protection enhancements were added for the purpose of proactively detecting exploitation of both known and unknown vulnerabilities. These protection mechanisms primarily center on detection and prevention of ROP-based exploits. Using these memory protection enhancements, EMET is even able to detect and prevent an ASLR/DEP bypass that was shown off at this year’s CanSecWest security conference.

EMET can be put into an “Audit mode” that will stop it from blocking offending processes, and instead report when a rule is triggered. This allows for compatibility testing before mass deployment and makes it much more realistic to be used as a reporting device if active blocking is too severe for a specific workstation. After rules are developed, EMET can be pushed out and managed through Group Policy.

As with any mitigation or protection mechanism, there is usually going to be some technique that bypasses the defense. After all, this is a never-ending struggle in a fight to secure highly valuable data. However, this does add on an additional layer that attackers will need to plan for and attempt to bypass. It becomes especially valuable in situations where legacy software is involved, when uninstalling just isn’t an option. In order to help secure your environment, we recommend that you at least test out EMET, and if it works for you, get it deployed as soon as possible. In order to help with the process, you can use your trusty Retina Network Security Scanner (audit ID 19247 & 19248) to locate machines on your network that do not yet have EMET deployed on them.