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Internet Explorer 8 - Data Execution Protection/NX

Affected Platforms

Clients - Windows XP | Windows Vista | Windows 7
Servers - Windows Server 2003 | Windows Server 2008 | Windows Server 2008 R2

Note  Internet Explorer 8 will enable DEP/NX protection when run on an operating system with the latest service pack. Windows XP SP3, Windows Server 2003 SP3, Windows Vista SP1, and Windows Server 2008 all have DEP/NX enabled by default in Internet Explorer 8.

Feature Impact

Severity - Medium
Frequency - Low

Note  Typically, any application that runs in Internet Explorer and is not compatible with DEP/NX will crash on startup and will not function. Internet Explorer may crash on startup if add-ons that are not compatible with DEP/NX are installed.

Description

DEP/NX is a security feature that helps mitigate memory-related vulnerabilities. As of Internet Explorer 8, all Internet Explorer processes enable the DEP/NX feature by default.

Manifestation of Impact

The Windows Kernel monitors a program's execution. If the Kernel detects an attempt to run code from a memory page that is not marked executable, the Kernel halts execution of the program, resulting in a "crash." This is a security measure to help ensure that memory-related vulnerabilities (for example, buffer overflows) in the application cannot be exploited in order to execute arbitrary code.

End-User Mitigation

  • Install a later version of the add-on or framework that is DEP/NX compatible.
  • Run Internet Explorer elevated as Administrator, and then disable DEP/NX using the Enable memory protection to help mitigate online attacks check box on the Internet Options / Advanced tab.

Developer Solution

Compile applications by using the latest versions of frameworks that are DEP compatible.

Leveraging Feature Capabilities

  • Use the /NXCOMPAT linker option to indicate DEP/NX compatibility
  • Opt your code into other available defenses like stack defense (/GS), safe exception handling (/SafeSEH), and ASLR (/DynamicBase)

Compatibility, Performance, Reliability, and Usability Testing

  • Test your code with DEP/NX enabled by using latest released Internet Explorer version on Windows Vista SP1 or later.
  • Test with Internet Explorer 7 on Windows Vista after enabling the DEP/NX option. To enable DEP/NX for Internet Explorer 7, run Internet Explorer as an administrator, then set the appropriate check box in the Tools > Internet Options > Advanced tab.
  • Run the Internet Explorer Compatibility Test Tool (IECTT), provided with the Application Compatibility Toolkit (ACT) to locate any potential issues due to the DEP/NX changes.

Links to Other Resources

 

 

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