Researchers from Offensive Security have found a way to disable the protection systems provided by the latest version of Microsoft’s Enhanced Mitigation Experience Toolkit (EMET).
EMET is designed to prevent software vulnerabilities from being exploited by using various mitigation technologies, including Structured Exception Handler Overwrite Protection (SEHOP), Data Execution Prevention (DEP), Heapspray Allocations, Null page allocation, Mandatory Address Space Layout Randomization (ASLR), Export Address Table Access Filtering (EAF) and Return Oriented Programming (ROP) mitigations.
Research papers such as “Bypassing EMET 4.1” and “EMET 4.1 Uncovered” detail mitigation bypass methods, but Offensive Security has focused on disarming EMET, rather than on bypassing mitigations, as this method gives an attacker the ability use generic shellcodes such as the ones generated by Metasploit. This also represents a generic way of disabling all protections, and “not having to rely on functions that are not critical to EMET when trying to defeat the MemProt ROP protection, especially when having ‘Deep Hooks’ enabled,” the company said.
The researchers managed to disarm EMET and get a shell after finding a global variable in the .data section of the EMET.dll file. The said variable, which is located on a memory page marked with read/write permissions, acts as a switch to enable or disable all the ROP protections at runtime.
“If we manage to zero out the general switch, all the ROP mitigations implemented by EMET would be disabled. This requires an attacker to build a ROP chain that will dynamically retrieve the base address of EMET.dll and overwrite the global variable with a zero,” Offensive Security wrote in a blog post.
Initially, experts only managed to get a shell by executing the exploit with a debugger attached, due to EMET’s EAF checks. However, they’ve succeeded in getting a shell outside the debugger after disarming EAF with a method described by security researcher Piotr Bania in January 2012.
The researchers tested their findings on Windows 7, Internet Explorer 8 and EMET 4.1 update 1. Offensive Security says Microsoft appears to be aware of the attack method since the company addressed the issue in the technical preview versions of EMET 5 and later. Microsoft could not immediately be reached for comment.
The exploit code for disarming EMET has been made available by Offensive Security. The company has also published a video to demonstrate the attack which is embedded below.
Disarming Enhanced Mitigation Experience Toolkit (EMET) from Offensive Security on Vimeo.
Eduard Kovacs (@EduardKovacs) is a managing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.
More from Eduard Kovacs
- China’s Offensive Cyber Operations in Africa Support Soft Power Efforts
- SANS Survey Shows Drop in 2023 ICS/OT Security Budgets
- Apple Patches 3 Zero-Days Likely Exploited by Spyware Vendor to Hack iPhones
- Cisco to Acquire Splunk for $28 Billion
- Car Cybersecurity Study Shows Drop in Critical Vulnerabilities Over Past Decade
- Omron Patches PLC, Engineering Software Flaws Discovered During ICS Malware Analysis
- Intel Launches New Attestation Service as Part of Trust Authority Portfolio
- Atos Unify Vulnerabilities Could Allow Hackers to Backdoor Systems
Latest News
- In Other News: New Analysis of Snowden Files, Yubico Goes Public, Election Hacking
- China’s Offensive Cyber Operations in Africa Support Soft Power Efforts
- Air Canada Says Employee Information Accessed in Cyberattack
- BIND Updates Patch Two High-Severity DoS Vulnerabilities
- Faster Patching Pace Validates CISA’s KEV Catalog Initiative
- SANS Survey Shows Drop in 2023 ICS/OT Security Budgets
- Apple Patches 3 Zero-Days Likely Exploited by Spyware Vendor to Hack iPhones
- New ‘Sandman’ APT Group Hitting Telcos With Rare LuaJIT Malware
