Challenges

Round 1 of the Grand Reverse Engineering Challenge has 4 challenges, described below. Some are compiled for Linux/x86/64, some are compiled for Linux/ARM/32. The ARM binaries run well on a Raspberry Pi 4 (they have been tested on RPI4 running 32 bit Raspbian). There are three types of challenges: deobfuscation, tampering, and extraction.

Note that the challenges do not necessarily represent the best protections available from the obfuscation tools we have at our disposal - rather, they were designed to be possible to crack. Our end goal with this competition is to collect information for the community on how attacks are carried out in the real world. In other words, this is not a competition between providers of obfuscation tools, but a competition between attackers! We do not provide information on which tool was used to protect which challenge, and which protective transformations were employed - figuring this out is part of the challenge.

For each challenge we use the scale LIGHT, MEDIUM, HEAVY to give a rough indication of the amount of protection (i.e. obfuscation and tamperproofing) that has been added. 

Round 1

  • Challenge 1 (  LIGHT   EXTRACT   X86   ARM  ): challenge-1-x86_64-Linux.exe  and challenge-1-armv7-Linux.exe read two unsigned  32-bit numbers in decimal form  from standard input and print a number to standard output. A successful submission consists of two 32-bit numbers that, when read from standard input, cause  the program to crash with a segmentation fault. The original program is about 600 lines of C, the  obfuscated program about 21,000 lines.
  • Challenge 2 (  MEDIUM   DEOBFUSCATE   X86  ): challenge-2-x86_64-Linux.exe and challenge-2-armv7-Linux.exe read two unsigned 32-bit numbers in decimal form from the command line and print a number to standard output. The goal is to deobfuscate the program and return it to idiomatic C. The original function is small, less than 100 lines of C.
  • Challenge 3 (  HEAVY   DEOBFUSCATE   X86  ): challenge-3-x86_64-Linux.exe takes 3 command line arguments, 32-bit unsigned integers in decimal form. For example, "challenge_3_linux_x86_64.exe 35329 234792379 1100292587" will produce an output of the form "Answer for x = 35329, y = 234792379, z = 1100292587 is 3546740429". The code defines a piecewise mathematical function on the inputs. Your job is to figure out what that function is. The answer is not elegant, but it is short: each part of the function can be written in one line.
  • Challenge 4 (  HEAVY   DEOBFUSCATE   X86  ): Challenge 4 ( challenge-4-x86_64-Linux.exe) is identical to Challenge 3, but uses a different type of protection.
  • Challenge 5 (  LIGHT   EXTRACT   ARM  ): challenge-5-armv7-Linux.exe takes a license key as its first argument on the command line. It is your job to find this key.
  • Challenge 6 (  MEDIUM   EXTRACT   ARM  ): challenge-6-armv7-Linux.exe is a protected version of the zip utility. A list of command-line arguments can be generated with “./challenge-6-armv7-Linux.exe --help”. An additional, undocumented command-line argument (-K “<some string>”) can be used to pass a key to the program. The program only produces valid zip-files when this key is correct. It is your job to find the correct key.
  • Challenge 7 (  LIGHT   TAMPER   ARM   X86  ): challenge-7-x86_64-Linux.exe and challenge-7-armv7-Linux.exe read two English words from standard input and print a number to standard output. The words are no longer than 12 characters, consist of the lower case letters a-z, and have been taken from this list. For two particular words the program will crash with a segmentation fault. Your task is to modify the program to remove the code that causes this crash (it will now print a number to standard output) while maintaning the same behavior as the original program for all other inputs.

You can download the challenges here [link will go live on May 21, 2021], and participate as described here.

Round 2

  • Coming soon!