Quick Answer
The correct answer is packing and obfuscation. This anti-forensic technique works by compressing or encrypting the original malicious executable and wrapping it with a small stub that decompresses or decrypts the code in memory at runtime, thereby altering the static file signature on disk. Because signature-based antivirus and forensic tools rely on static analysis of the binary, this runtime modification allows the malware to evade detection entirely. On the Computer Hacking Forensic Investigator CHFI exam, this concept tests your understanding of how attackers bypass signature-based detection and why dynamic analysis is critical; a common trap is confusing packing with simple encryption, but remember that packing involves both compression and a runtime stub. For a memory tip, think of a packed suitcase: the contents are hidden until unpacked in memory, changing the outward appearance.
This CHFI practice question tests your understanding of mobile and malware forensics. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
During malware analysis, an analyst discovers that a sample uses a technique to modify its own code at runtime to evade signature detection. Which anti-forensic technique does this describe?
Log wiping
Why wrong: Log wiping removes traces from logs, not self-modification.
Packing/Obfuscation
Packing and obfuscation techniques modify the code to evade detection; self-modifying code is a form of obfuscation.
Encryption
Why wrong: Encryption protects data but does not involve runtime code modification.
Timestomping
Why wrong: Timestomping alters file timestamps, not code.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Packing/Obfuscation
The technique of modifying code at runtime to evade signature detection is known as packing or obfuscation. Packers compress or encrypt the original executable and wrap it with a small stub that decompresses or decrypts the code in memory during execution, thereby altering the static file signature. This runtime modification allows the malware to bypass signature-based antivirus and forensic tools that rely on static analysis of the binary on disk.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Log wiping
Why it's wrong here
Log wiping removes traces from logs, not self-modification.
Packing/Obfuscation
Why this is correct
Packing and obfuscation techniques modify the code to evade detection; self-modifying code is a form of obfuscation.
Related concept
Read the scenario before looking for a memorised answer.
Encryption
Why it's wrong here
Encryption protects data but does not involve runtime code modification.
Timestomping
Why it's wrong here
Timestomping alters file timestamps, not code.
Common exam traps
Cisco often tests the distinction between encryption as a general concept and packing/obfuscation as a specific anti-forensic technique that combines encryption with runtime code modification to evade static signature detection.
Detailed technical explanation
Under the hood, a packer like UPX or Themida replaces the original PE header with a compressed or encrypted payload and a small decompression stub. When executed, the stub runs first, decompresses the original code into memory, and then transfers control to it, meaning the static file on disk never matches the in-memory code. In real-world scenarios, advanced packers use multiple layers of encryption, anti-debugging tricks, and import address table (IAT) obfuscation to further hinder dynamic analysis and memory dumping.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
Mobile and Malware Forensics — This question tests Mobile and Malware Forensics — Read the scenario before looking for a memorised answer..
The correct answer is: Packing/Obfuscation — The technique of modifying code at runtime to evade signature detection is known as packing or obfuscation. Packers compress or encrypt the original executable and wrap it with a small stub that decompresses or decrypts the code in memory during execution, thereby altering the static file signature. This runtime modification allows the malware to bypass signature-based antivirus and forensic tools that rely on static analysis of the binary on disk.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
This CHFI practice question is part of Courseiva's free EC-Council certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the CHFI exam.
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