Introducing EMET v4 Beta

Great news!  Today we are proud to announce a beta release of the next version of the Enhanced Mitigation Experience Toolkit (EMET) – EMET 4.0.  Download it here:

EMET is a free utility that helps prevent memory corruption vulnerabilities in software from being successfully exploited for code execution.  It does so by opt-ing in software to the latest security mitigation techniques.  The result is that a wide variety of software is made significantly more resistant to exploitation – even against zero day vulnerabilities and vulnerabilities for which an available update has not yet been applied.  We encourage you to test out the beta release by downloading and installing it, asking questions about the new features, and reporting any issues you find for us to address before the final release.  We plan to officially release EMET 4.0 on May 14, 2013.

The feature set for this new version of the tool was inspired by our desire for EMET to be an effective mitigation layer for a wider variety of potential software exploit scenarios, to provide stronger protections against scenarios where EMET protection already exists, and to have a way to respond to 0day exploits as soon as possible.  Here are the highlights of the EMET 4.0 feature set:

  •        EMET 4.0 detects attacks leveraging suspicious SSL/TLS certificates
  •        EMET 4.0 strengthens existing mitigations and blocks known bypasses
  •        EMET 4.0 addresses known application compatibility issues with EMET 3.0
  •        EMET 4.0 enables an Early Warning Program for enterprise customers and for Microsoft
  •        EMET 4.0 allows customers to test mitigations with “Audit Mode”

SSL/TLS Certificate Trust features

EMET 4.0 allows users to configure a set of certificate pinning rules to validate digitally signed certificates (SSL/TLS certificates) while browsing with Internet Explorer. This option allows users to configure a set of rules able to match specific domains (through their SSL/TLS certificates) with the corresponding known Root Certificate Authority (RootCA) that issued the certificate. When EMET detects the variation of the issuing RootCA for a specific SSL certificate configured for a domain, it will report this anomaly as an indicator of a potential man-in-the-middle attack.

Advanced users can also add exceptions for each pinning rule.  This will allow EMET to accept SSL/TLS certificates even if the pinning rule doesn’t match.  Exceptions are related to some properties of the RootCA certificate, such as key size, hashing algorithm, and issuer country.

Strengthened mitigations, blocking bypasses

We learned a great deal during the “Technical Preview” phase of EMET 3.5.  We saw researchers poking and presenting clever tricks to bypass EMET’s anti-ROP mitigations.  EMET 4.0 blocks these bypasses.  For example, instead of hooking and protecting only functions at the kernel32!VirtualAlloc layer of the call stack, EMET 4.0 will additional hook lower level functions such as kernelbase!VirtualAlloc and ntdll!NtAllocateVirtualMemory.  These “Deep Hooks” can be configured in EMET’s Advanced Configuration.  We have seen exploits attempt to evade EMET hooks by executing a copy of the hooked function prologue and then jumping to the function past the prologue.  With EMET 4.0’s “Anti detours” option enabled, common shellcode using this technique will be blocked.  Finally, EMET 4.0 also includes a mechanism to block calls to banned API’s.  For example, a recent presentation at CanSecWest 2013 presented a method of bypassing ASLR and DEP via ntdll!LdrHotPatchRoutine.  EMET 4.0’s “Banned API” feature blocks this technique.

Application compatibility fixes

Users of previous versions of EMET had encountered isolated compatibility issues when enabling mitigations on both Microsoft and third party software.  EMET 4.0 addresses all these known appcompat issues.  That list includes issues in the following areas:

          Internet Explorer 9 and the Snipping Tool

          Internet Explorer 8’s Managed Add-ons dialog

          Office software through SharePoint

          Access 2010 with certain mitigations enabled

          Internet Explorer 10 on Windows 8

The EMET 4.0 installer also opts-in protection rules with certain mitigations disabled where we know a mitigation interacts poorly with certain software.  Examples include Photoshop, Office 2013’s Lync, GTalk, wmplayer, and Chrome.

Early Warning Program for enterprise customers and for Microsoft

When an exploitation attempt is detected and blocked by EMET, a set of information related to the attack is prepared with the Microsoft Error Reporting (MER) functionality.  For enterprise customers collecting error reports via tools like Microsoft Desktop Optimization Package or the Client Monitoring feature of System Center Operations Manager, these error reports can be triaged locally and used as an early warning program indicating possible attacks against the corporate network.  For organizations that typically send all error reports to Microsoft, this information will add to the set of indicators we use to hunt attacks in the wild, and will facilitate the remediation of issues with security updates before vulnerabilities become a large scale threat. The EMET Privacy Statement (available also via the main EMET window) includes more information about the type of data that will be sent in the error report via Microsoft Error Reporting.  The Early Warning Program is enabled by default for the EMET 4.0 Beta and can be disabled in the EMET UI or via the EMET command line component.  We are eager to hear customer feedback about this feature to help shape the Early Warning Program for the EMET 4.0 final release.

Audit Mode

When previous versions of EMET detected exploitation attempts, it would report the attack via the EMET agent and then terminate the program to block the attack.  For EMET 4.0, in response to customer feedback, we provided an option to configure EMET’s behavior when it detects an exploitation attempt.  The default option remains to terminate the application.  However, customers wanting to test EMET in a production environment can instead switch to “Audit Mode” to report the exploitation attempt but not terminate the process.  This setting is not applicable for all mitigations but we provide this option whenever possible.


Other Improvements

EMET 4.0 includes a bunch of other improvements.  The quantity of new features and volume of work put into this release is the reason we skipped the EMET 3.5 full release and jumped straight to EMET 4.0.  Please refer to the EMET 4.0 Beta Users Guide for the full set of features but here are several other highlights:

          EMET Notifier becomes EMET Agent, with new duties and functionalities

          More granular reporting options (tray icon, event log, both, or none)

          New default profiles for both mitigations and Certificate Trust

          Registry configuration to customize the EMET Agent’s messaging

          Optimized RopCheck for significantly better performance

          Numerous UI tweaks to make EMET easier to use

          Enable wildcard support when adding applications to be protected

          Allow processes to be protected even if they do not have .exe extension

          Switched to .NET Framework 4.0

          EMET is an officially supported Microsoft tool with support available for customers with Premier contract

We are eager to hear feedback on this new version of EMET!  This beta period is a short four weeks – we learned our lesson from the long EMET 3.5 Technical Preview about crisp timelines and short beta periods.  We need to get customer feedback during this beta period, before the official release of EMET 4.0.  Some of the EMET 4.0 feature set came straight from customer feedback. We want to make EMET a tool that you feel great about deploying and configuring in your environment.  This beta period provides an option to get the feedback of early adopters before it goes live to everyone.  Please email us at with any feedback, questions, or suggestions.  And download EMET 4.0 Beta today and try it out. 


The EMET Team