challenge info  
Name: Zaza
Category: Rev
Difficulty: Easy
Points: 50
Link:

 

 

Description

Bedtime!

nc challs.actf.co 32760

zaza

Approach

the program makes some checks before giving us flag

 

check#1

the program prompts I'm going to sleep. Count me some sheep:

looking into the binary we find that the number is 4919

Untitled

 

check#2

it then prompts Nice, now reset it. Bet you can't: it asks for x such that x * 4919 ≠ 1

Untitled

 

check#3

it then asks Okay, what's the magic word? looking it the binary we can see that it perform xor on a string with a key

Untitled Untitled after the xor we got the magic words

Untitled

 

┌──(kali㉿iasad)-[~/CTFs/angstorm]
└─$ nc challs.actf.co 32760
I'm going to sleep. Count me some sheep: 4919
Nice, now reset it. Bet you can't: 1
Okay, what's the magic word?
SHEEPSHEEPSHEEPSHEEPSHEEPSHEEPSHEEPSHEEPSHEEPSHEEPkd

actf{g00dnight_c7822fb3af92b949}

 


Flag: actf{g00dnight_c7822fb3af92b949}