Hardware-Based Countermeasures for Customized OS Build in Embedded Environment

B.

The hardware that the company has procured is capable of reducing the likelihood of successful buffer overruns while executables are processing. The question is asking about the critical hardware-based countermeasure that must be included in the customized OS build to take advantage of this capability.

The most likely hardware-based countermeasure that the company has procured is the NX/XN bit, which stands for No-Execute or eXecute Never bit. This bit is a hardware-level security feature that prevents the execution of code from a non-executable memory region. In other words, it helps to prevent buffer overruns by preventing malicious code from executing in memory that was not intended for code execution.

To take advantage of this hardware-based countermeasure, the OS must support the NX/XN bit. Therefore, option B is the correct answer.

Let's briefly discuss the other options:

• Application whitelisting (option A) is a security feature that allows only approved applications to run on a system. While it is a good security practice, it is not related to the hardware-based countermeasure described in the question.
• Address space layout randomization (ASLR) (option C) is a security technique that randomly arranges the positions of key data areas, making it more difficult for an attacker to predict the location of an exploit in memory. Again, it is a good security practice, but it is not directly related to the hardware-based countermeasure described in the question.
• TrustZone (option D) is a security extension of the ARM processor architecture that provides a secure environment for executing trusted code. While TrustZone is a good security feature, it is not related to the hardware-based countermeasure described in the question.
• SCP (option E) stands for Secure Copy Protocol. SCP is a network protocol that allows files to be securely transferred between hosts over a network. SCP is not related to the hardware-based countermeasure described in the question.

Therefore, option B (NX/XN bit) is the correct answer.