VishwaCTF-22 => Overcook (Reverse Engineering)

Challenge Info

Description: Alright, this time you’ll need to control some numerical representations. Can you get the flag from this program?

Vishwa CTF

Solution

So, as usual, opening it in Ghidra Code Analyzer and checking its functions

So here, we see something interesting, the “printflag” function. So clicking it and checking the de-compiler (this seems more interesting than main this time 😋).

Here, we can see multiple numbers which would be printed. But these numbers looks a bit interesting, these all have three digits, decimal format also have three digits. So, entering it to CyberChef and entering “From Decimal” in recipe and seeing the output

So here we get the text “r3vers1ng_dud3”. Since the flag format is “vishwaCTF{s3cr3t}”, so our final flag will be “vishwaCTF{r3vers1ng_dud3}

Takeaways

  • Decode all text which seems suspicious.

Get more VishwaCTF-22 writeups here

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