| Task | Memory |
|---|---|
| Competition | CONFidence CTF 2014 |
| Location | Krakow, Poland |
| Category | Reverse engineering |
| Platform | Windows x86 |
| Scoring | 50 pts (easy) |
| Number of solves | 2 out of 11 participants |
Destruction is key.
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- Unpack a slightly corrupted UPX-packed executable.
- Reverse engineer a very simple virtual machine implemented in the challenge, consisting mostly of arithmetic and binary operators.
- Calculate the textual string expected by the VM program, either by reversing all operations or brute-forcing the value of each byte.
- Notice that with the correct input, the real flag is constructed in memory in a destructor routine.