Edge Now Blocks Code Injection

Microsoft’s Edge browser’s rendering engine is getting an update that includes a security feature designed to block unauthorized code injection attempts.

Way back in May, Microsoft removed support on Edge for legacy technologies and features, including ActiveX, toolbars, VB Script and Browser Helper Objects (BHO), arguing the capabilities of HTML5 significantly reduce the need for such extensions.

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The company has improved Edge security even further with the introduction of EdgeHTML 13, the latest version of the web browser’s rendering engine.

While removing support for ActiveX and BHO improves security, toolbars and other unwanted or malicious third-party components can still end up installed by injecting dynamic-link libraries (DLLs) into the Edge process.

In an effort to prevent these types of attacks and make browser exploits more difficult to carry out, the latest Edge update blocks DLL injections into the browser process. Only components signed by Microsoft and WHQL-signed device drivers will end up allowed to load, Microsoft said.

“This DLL code signing mitigation will make it less likely for the browser to be hacked,” said Crispin Cowan, senior program manager at Microsoft Edge in a blog post. “It also reinforces Microsoft Edge against unwelcome binary ‘extensions’ that slow down and or destabilize the browser.

“Code integrity enforcement can be done in the process, or in the kernel. Enforcement in the process is only useful if the threat model is that the process is not yet compromised, because if it has been compromised, then the hacked process can just disable the code integrity check for itself,” Cowan said. “Microsoft Edge uses enforcement in the kernel, which is robust against a compromised process, so that even a pernicious ad injector cannot turn off the code integrity check. With the browser process model and the Windows kernel helping each other in this way, Microsoft Edge becomes the first and only PC browser with library content integrity protection.”

Microsoft said there is no such thing as a silver bullet when it comes to browser security, but the company believes the latest improvements will significantly increase the sophistication and expense needed to attack Edge users.