Understanding and Deobfuscating Malware: Reverse Engineering Procedures
Question
During an incident investigation, a security analyst acquired a malicious file that was used as a backdoor but was not detected by the antivirus application.
After performing a reverse-engineering procedure, the analyst found that part of the code was obfuscated to avoid signature detection.
Which of the following types of instructions should the analyst use to understand how the malware was obfuscated and to help deobfuscate it?
Answers
Explanations
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A. B. C. D. E.C.
During the process of reverse-engineering, the security analyst can analyze the malicious file to understand its behavior and how it was able to evade detection. In this scenario, the analyst found that part of the code was obfuscated to avoid signature detection. Obfuscation is a technique used by malware authors to hide their malicious code, making it difficult for security software to detect it.
To deobfuscate the malware, the analyst needs to understand how the code was obfuscated. One common obfuscation technique is to use XOR (exclusive OR) operations to manipulate the data. The XOR operation is used to perform bitwise comparisons between two values, and it can be used to mask the original value.
Therefore, the type of instruction that the analyst should use to understand how the malware was obfuscated and to help deobfuscate it is the XOR instruction.
The other instructions listed in the answer choices, such as MOV, ADD, SUB, and MOVL, are commonly used instructions in assembly language but do not directly relate to the obfuscation technique used in this scenario.
In summary, XOR instruction should be used to analyze how the malware was obfuscated and help deobfuscate it.
