Cyber Apocalypse
2024
Makeshift
Weak and starved, you struggle to plod on. Food is a commodity at this stage, but you can’t lose your alertness - to do so would spell death. You realise that to survive you will need a weapon, both to kill and to hunt, but the field is bare of stones. As you drop your body to the floor, something sharp sticks out of the undergrowth and into your thigh. As you grab a hold and pull it out, you realise it’s a long stick; not the finest of weapons, but once sharpened could be the difference between dying of hunger and dying with honour in combat.
Crypto
300 points
Walkthrough
We start by downloading the source files.
We are give a
source.py
file and an output.txt
file. It looks like the output is generated using the source code, so we start by analyzing the source code.from secret import FLAG
flag = FLAG[::-1]
new_flag = ''
for i in range(0, len(flag), 3):
new_flag += flag[i+1]
new_flag += flag[i+2]
new_flag += flag[i]
print(new_flag)
This looks like it could be easily reversed. We can modify the script to decrypt the output:
output = "!?}De!e3d_5n_nipaOw_3eTR3bt4{_THB"
def decrypt(text):
flag = text
new_flag = ''
for i in range(0, len(flag), 3):
new_flag += flag[i+2]
new_flag += flag[i]
new_flag += flag[i+1]
return new_flag[::-1]
print(decrypt(output))
Running this script gives us the flag:
HTB{4_b3tTeR_w3apOn_i5_n3edeD!?!}
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