The correct next step is to use UPX with the -d flag to decompress the executable. This is because UPX (Ultimate Packer for Executables) is a widely used open-source packer that compresses Windows executables to reduce their size, and the PEiD output “UPX 0.89.6 - 1.02 / 1.05 - 1.24” specifically identifies the packing algorithm and version. Running `upx -d` reverses the compression, restoring the original executable code for static analysis, which is the standard forensic technique before attempting disassembly or dynamic analysis. On the Computer Hacking Forensic Investigator CHFI exam, this scenario tests your ability to recognize common packers and apply the correct unpacking tool—a critical skill when analyzing malware or suspicious binaries where few readable strings appear. A common trap is to jump straight to a debugger or hex editor, but UPX’s own decompression flag is the quickest and most reliable method. Memory tip: think “UPX -d” as “UPX decompress”—the flag is always lowercase d for decompress.
CHFI Mobile and Malware Forensics Practice Question
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.
An analyst suspects a Windows executable is packed. They run `strings` on the file and see few readable strings, and PEiD reports 'UPX 0.89.6 - 1.02 / 1.05 - 1.24'. Which static analysis technique should the analyst use NEXT to extract the original code?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use UPX with the -d flag to decompress the executable
Option A is correct because UPX (Ultimate Packer for Executables) is a common packer that compresses Windows executables. The PEiD output 'UPX 0.89.6 - 1.02 / 1.05 - 1.24' confirms the file is packed with UPX. Running `upx -d` (decompress) reverses the packing, restoring the original executable code for static analysis. This is the standard next step before attempting disassembly or dynamic analysis.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Use UPX with the -d flag to decompress the executable
Why this is correct
UPX can decompress its own packed files. Running `upx -d file.exe` will restore the original code for further analysis.
Related concept
Read the scenario before looking for a memorised answer.
✗
Search for known YARA rules matching UPX
Why it's wrong here
YARA rules are for detection, not for extracting original code. Unpacking is required first.
✗
Run the executable in Cuckoo Sandbox to obtain dynamic analysis
Why it's wrong here
Dynamic analysis is useful but the question asks for static analysis technique. Unpacking is a static step.
✗
Load the file into IDA Pro and attempt to disassemble directly
Why it's wrong here
Disassembling a packed binary without unpacking yields obfuscated code. Unpacking first is recommended.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the distinction between detection (YARA), dynamic analysis (sandbox), and direct disassembly (IDA) versus the correct unpacking step, trapping candidates who think any analysis tool can handle packed files without prior decompression.
Detailed technical explanation
How to think about this question
UPX works by compressing the PE sections and appending a decompression stub. The `-d` flag triggers the stub's inverse operation, restoring the original import table, relocations, and code. In real-world malware analysis, failing to unpack first leads to false negatives in signature detection and incorrect disassembly, as the stub's code is trivial compared to the payload.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the CHFI exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this CHFI question in full detail.
Mobile and Malware Forensics — This question tests Mobile and Malware Forensics — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use UPX with the -d flag to decompress the executable — Option A is correct because UPX (Ultimate Packer for Executables) is a common packer that compresses Windows executables. The PEiD output 'UPX 0.89.6 - 1.02 / 1.05 - 1.24' confirms the file is packed with UPX. Running `upx -d` (decompress) reverses the packing, restoring the original executable code for static analysis. This is the standard next step before attempting disassembly or dynamic analysis.
What should I do if I get this CHFI question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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