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Tag: Flag Checker

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Flag Checker

Flag checkers are a common type of challenge in the Reverse Engineering category.

An executable or script called a flag checker takes the player's input and outputs whether that input matches the flag.

These challenges may also be called "crackmes" in a broader sense. (automatically translated from Japanese)

minaminao
·Updated May 3, 2026
Flag Checker Challenges

x32 ABI flag checker

Daily AlpacaHackTopic: ABIReleased: Oct 19, 2026

39 solves
Rev

by

tan90909090

tan90909090

This is a flag checker built to use the x32 ABI!

NOTE: There is a plan to remove the x32 ABI from the Linux kernel. Consequently, it may become impossible to execute the provided file for this challenge in the future. However, since this challenge can also be solved through static analysis alone, I encourage you to give it a try.

Beginner Hint: How to Approach the Challenge
  • Some analysis tools do not handle x32 ABI binaries well. For example, they may fail to execute, disassemble using a wrong ISA, or produce a decompilation output that is difficult to read.
  • If you encounter such issues, trying a different tool is one possible solution.
x32-abi-flag-checker

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