Microsoft Details IE 8 Security Default Change

The company will enable DEP/NX (Data Execution Prevention/No Execute) by default in IE 8 when running on Windows Vista and Windows Server 2008.

SAN FRANCISCO-Microsoft plans to make a key Internet Explorer default change to thwart attackers trying to hack into its Web browser.

The software maker will enable DEP/NX (Data Execution Prevention/No Execute) by default in IE 8 when the browser is running on Windows Vista and Windows Server 2008, a major tweak aimed at mitigating browser-based vulnerabilities.
DEP/NX is already available in IE 7, but it's turned off by default because of compatibility issues.

With the default change, IE 8 automatically gets a security feature that prevents an application or service from executing code from a nonexecutable memory region. When used in tandem with additional security mechanisms, DEP/NX can help to reduce the effectiveness of hacker attacks.

According to Microsoft Program Manager Eric Lawrence, the DEP/NX protection will apply to Internet Explorer and all add-ons loaded by the browser. "No additional user interaction is required to provide this protection, and no new prompts are introduced," Lawrence said.

What kind of security features do people expect to see in IE 8? Click here to read more.

This means that IE add-on developers will have to make code changes to ensure a smooth ride once IE 8 is released to the general public.

Microsoft's recommendations to IE developers include:

  • If code depends on older versions of ATL (Active Template Library), please rebuild it with ATL v7.1 Service Pack 1 or later (Visual Studio 2005 includes ATL 8.0).
  • Set the /NXCompat linker option to indicate that an extension is compatible with DEP/NX.
  • Test code with DEP/NX enabled using IE 8 Beta 1 on Windows Vista SP1. (Alternatively, test with IE 7 on Windows Vista after enabling the DEP/NX option. To enable DEP/NX for IE 7, Run IE as an administrator, then set the appropriate checkbox in the Tools > Internet Options > Advanced tab.)
  • Opt code into other available defenses like stack defense (/GS), safe exception handling (/SafeSEH) and ASLR (/DynamicBase)

"In rare cases where an add-on is not DEP/NX-compatible for reasons other than outdated ATL usage, a group policy option will be available to allow an organization to opt out of DEP/NX for Internet Explorer until an updated version of the broken add-on can be deployed," Lawrence said.

He also said the DEP/NX change means IE 8's new security features will target three major sources of security exploits-social engineering, and Web server- and browser-based vulnerabilities. It will feature a revamped anti-phishing/anti-malware component called Safety Filter, which blocks Web sites that are known to contain malicious software that could harm users' computers or steal sensitive user information.

Lawrence said IE 8 will also offer greater control over ActiveX controls and new AJAX (Asynchronous JavaScript and XML) features, XDomainRequest and XDM, for safer mashups.