HeroCTF v3 writeup Rev-Easy assembly

Prof.bubs
2 min readApr 26, 2021

This assembly is based on reverse engineering

src-google images

From the question, we can understand that the flag for this challenge should come in the format Hero{input: modified}. So there are 2 key things we have to find here. One is input and another one is modified. The challenge provided us with asm file.

EasyAssembly.asm

upon inspection, we can understand that both input and modified are integer values.

EasyAssembly.asm

The modified value is given inside the if condition.

e

From this, we can understand the input bit shifts left 2 times. So we can open an online bit shift convertor to find the input value.

https://bit-calculator.com/bit-shift-calculator

so the input value is 5349616. Now putting all this together we get our flag as Hero{5349616:1337404}.

That's it, guys !. We got our flag to submit. This was fairly an easy one. We didn't have to use any tools and all we needed to understand was a bit of assembly language. Thank you for reading the write-up and hope you have a good day.

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