How do you deal with incomplete or inaccurate decompilation results?

1 Obfuscated code

One of the main challenges for decompilation is obfuscated code, which is code that has been deliberately modified to make it harder to read and analyze. Obfuscated code can use various techniques, such as encryption, packing, anti-debugging, junk code, or control flow flattening, to hide the original code and logic. To deal with obfuscated code, you need to use tools and methods that can unpack, decrypt, or simplify the code before decompiling it. For example, you can use dynamic analysis tools, such as debuggers or emulators, to trace the execution of the code and identify the unpacking routines or decryption keys. You can also use static analysis tools, such as disassemblers or hex editors, to remove or modify the obfuscating features or patterns in the code.

2 Unsupported features

Another reason for decompilation errors is unsupported features, which are features or constructs that the decompiler cannot handle or translate correctly. Unsupported features can include complex data structures, custom calling conventions, indirect calls, or compiler optimizations. To deal with unsupported features, use your knowledge and experience to manually fix or annotate the decompiled code. For example, you can use the disassembly view or the hex view to compare the decompiled code with the original binary code and spot any discrepancies or missing information. Use the comment or rename functions of the decompiler to add notes or labels to the decompiled code to clarify or correct its meaning or purpose.

3 Incomplete input

A third reason for decompilation errors is incomplete input. This is when the decompiler doesn't have enough information or context to produce accurate results. Incomplete input can occur when the decompiler cannot access or analyze the external libraries, resources, or dependencies that the code relies on. To deal with incomplete input, you need to provide the decompiler with as much relevant information as possible. Use the import or export functions of the decompiler to load or save the external files or data that the code needs. You can also use the type or structure functions of the decompiler to define or edit the data types or formats that the code uses.

4 Decompiler limitations

Another reason for decompilation errors is decompiler limitations, which are the inherent limitations or bugs of the decompiler itself. Decompiler limitations can affect the quality, readability, or correctness of the decompiled code. To deal with decompiler limitations, you need to be aware of the strengths and weaknesses of the decompiler you are using and choose the best one for your specific case. For example, you can use different decompilers, such as Ghidra, IDA Pro, or JEB, to compare and cross-check the decompiled code and see which one gives you the most reliable or consistent results. Also use the feedback or support functions of the decompiler to report any issues or errors you encounter and request improvements or updates.

5 Decompiler output

The final step for dealing with decompilation errors is to evaluate and verify the decompiler output. The decompiler output is the result of the decompilation process, which is usually a high-level language code, such as C, Java, or Python. To evaluate and verify the decompiler output, you need to use your critical thinking and analytical skills to check if the decompiled code makes sense and matches your expectations. You can use the pseudocode view or the graph view of the decompiler to examine the structure and flow of the decompiled code and see if it reflects the intended functionality or logic of the code. You can also use the testing or validation functions of the decompiler to run or simulate the decompiled code and see if it produces the same output or behavior as the original code.

Decompilation is a valuable skill for malware analysis, but it is not a magic bullet that can solve all your problems. You need to be prepared to face and overcome the challenges and limitations of decompilation and use a combination of tools and techniques to achieve the best results. By following these steps, you can deal with incomplete or inaccurate decompilation results and improve your malware analysis skills.