NXTEST

Data Execution Prevention (DEP) Test

by Robert Schlabbach

What is this?

Starting with Windows XP Service Pack 2 and Windows Server 2003 Service Pack 1, Windows supports a new security enhancement called Data Execution Prevention (DEP). This feature prevents execution of program code in memory regions which normally do not contain any program code, such as the program stack, the process heap or data segments. Certain types of viruses or worms infect computers by provoking a buffer overrun in a vulnerable application to insert and execute their own, malicious code. With Data Execution Prevention (DEP) such attempts will be detected by the CPU and stopped by the operating system, thus ending a vulnerable application instead of allowing it to infect the computer with a virus or worm.

Note that this will not secure you from any malicious executables you may run voluntarily, such as e-mail attachments or downloads from unverified web sites, which may contain a virus, worm or trojan.

NXTEST is an application which allows you to check if Data Execution Prevention (DEP) is active on your computer by attempting to execute program code from a data segment, the process heap and the program stack, and reports whether all attempts were prevented by the operating system or not.

What do I need?

While you can run NXTEST on any 32-bit or 64-bit Windows version, your system can only support Data Execution Prevention (DEP) if it has:

• A 64-bit CPU featuring No Execute (NX) support
  (e.g. AMD Athlon 64, AMD Opteron or Intel Itanium)

• Windows XP (32-bit Editions) with Service Pack 2 or later
  Windows XP (64-bit Editions) with Service Pack 1 or later
  Windows Server 2003 (32-bit and 64-bit Editions) with Service Pack 1 or later

Download

Download NXTEST Version 1.00: NXTEST10.ZIP (14,036 bytes)

This archive contains three executables:

• NXTEST.EXE is the 32-bit test application, which runs on all Windows versions.

• NXTEST64.EXE is the 64-bit test application for x86-64 (AMD64) CPUs.
  This executable will only run on a Windows 64-Bit Edition for 64-bit Extended Systems.

• NXTEST_IA64.EXE is the 64-bit test application for Intel Itanium CPUs.
  This executable will only run on a Windows 64-Bit Edition for Intel Itanium Systems.

Further Reading

To find out further details about Data Execution (DEP) and No Execute (NX), follow these links:

Microsoft Technet Article about Memory protection technologies in Service Pack 2 for Windows XP

Microsoft MSDN Article about security technologies in Windows XP SP2, look under Memory protection

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