Researchers bypass protections in Microsoft's EMET anti-exploitation tool

The tool can't protect against determined attackers with customized exploits, researchers from Bromium claim

Security researchers managed to bypass the protections offered by Microsoft's Enhanced Mitigation Experience Toolkit (EMET), a utility designed to detect and block software exploits, and concluded that the tool would not be effective against determined attackers.

EMET can be used to apply 12 different security mitigations to other programs running on the computer. These mitigations are designed to block common techniques used in software exploits, like Return Oriented Programming (ROP), a technique that exploit authors use to defeat security defenses and execute malicious code on the system.

Researchers from Bromium, a company that develops security technologies based on micro-virtualization, investigated the protections offered by EMET and found that all of them can be bypassed if the attacker is determined enough.

"We found that EMET was very good at stopping pre-existing memory corruption attacks (a type of hacker exploit)," said Jared DeMott, principal security researcher at Bromium, Monday in a blog post. "But we wondered: is it possible for a slightly more technical attacker to bypass the protections offered in EMET? And yes, we found ways to bypass all of the protections in EMET."

DeMott was one of the three finalists in Microsoft's BlueHat Prize competition in 2012 through which the company rewarded security researchers for developing defensive techniques against software exploits.

While other researchers have documented methods of bypassing some EMET protections before, DeMott and the Bromium team investigated ways to defeat all of them. They presented their findings in a research paper published Monday and used the techniques to modify a known browser exploit previously blocked by EMET to bypass all defenses in the latest version of the toolkit -- version 4.1.

"We provided our research to Microsoft before speaking about these problems publically," DeMott said. "We also provided recommendations to upgrade the protections where possible."

Microsoft did not immediately respond to a request for comment.

According to DeMott, the company will recognize their work in the next EMET release -- version 5.

That version of the utility might also include some of the fixes recommended by the Bromium researchers. However, even if that happens, there's a deeper problem that prevents EMET from being a truly effective at stopping exploits -- the fact that it runs from user space and not at the kernel level.

"Many of the weaknesses are generic in nature and unlikely to be sufficiently addressed by userland protection technologies like EMET," the Bromium researchers said in their paper.

"The impact of this study shows that technologies that operate on the same plane of execution as potentially malicious code offer little lasting protection," DeMott said. "This is true of EMET and other similar userland protections. That's because a defense that is running in the same space as potentially malicious code can typically be bypassed, since there's no 'higher' ground advantage as there would be from a kernel or hypervisor protection."

Microsoft acknowledges in EMET's documentation that the tool blocks common exploitation techniques, but does not guarantee that vulnerabilities cannot be exploited. According to the EMET mitigation guidelines, the mitigations in EMET work as additional obstacles that an exploit author would have defeat in order to exploit vulnerabilities, so the goal of these obstacles is to make exploitation as difficult as possible to perform.

The real question is not whether EMET can be bypassed, but whether it sufficiently raises the cost of exploitation, the Bromium researchers said in their paper. "The answer to that is likely dependent upon the value of the data being protected. For organizations with data of significant value, we submit that EMET does not sufficiently stop customized exploits."

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.

Tags MicrosoftintrusionpatchesExploits / vulnerabilitiesDesktop securityDetection / preventionBromium

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments

Father’s Day Gift Guide

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Laura Johnston

MSI GS65 Stealth Thin

If you can afford the price tag, it is well worth the money. It out performs any other laptop I have tried for gaming, and the transportable design and incredible display also make it ideal for work.

Andrew Teoh

Brother MFC-L9570CDW Multifunction Printer

Touch screen visibility and operation was great and easy to navigate. Each menu and sub-menu was in an understandable order and category

Louise Coady

Brother MFC-L9570CDW Multifunction Printer

The printer was convenient, produced clear and vibrant images and was very easy to use

Edwina Hargreaves

WD My Cloud Home

I would recommend this device for families and small businesses who want one safe place to store all their important digital content and a way to easily share it with friends, family, business partners, or customers.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?