vm1.exe implements a simple 8-bit virtual machine (VM) to try and stop reverse engineers from retrieving the flag. The VM’s RAM contains the encrypted flag and some bytecode to decrypt it. Can you figure out how the VM works and write your own to decrypt the flag? A copy of the VM’s RAM has been provided in ram.bin (this data is identical to the ram content of the malware’s VM before execution and contains both the custom assembly code and encrypted flag).

 

Rules & Information
  • You are not require to run vm1.exe, this challenge is static analysis only.
  • Do not use a debugger or dumper to retrieve the decrypted flag from memory, this is cheating.
  • Analysis can be done using the free version of IDA Pro (you don’t need the debugger).

 

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Password: MalwareTech