Nuclear Sale

Platform: HackTheBox | Category: Cryptography | Difficulty: Easy | Author: D3v0o0Nu11 | Date: 2026-02-10

Description

Plutonium Labs is a private laboratory experimenting with plutonium products. A huge sale is going to take place and our intelligence agency is interested in learning more about it. We have managed to intercept the traffic of their mail server. Can you find anything interesting?

Solution Approach

Core idea: Identify the weakness from source review or fingerprinting first. Iterate with incremental payloads instead of guessing.

Steps

1. In this challenge we're given a pcap file.
2. At first i tried to ran strings to the file rather open it on wireshark.
3. Then found 3 things that could be our interest.

ENCRYPTED INFORMATION

2 Ciphertext encrypted with unknown key

1. Since i'm not a fond in crypto, kinda confused what to do, then i found a message that indicate a XOR operations (?)

2. Since all encrypted text are XORed with the same key, hence we can apply this:

 py read-only • copy allowed Copy
from pwn import * 

enc_info = '6b65813f4fe991efe2042f79988a3b2f2559d358e55f2fa373e53b1965b5bb2b175cf039'
cipher_1 = 'fd034c32294bfa6ab44a28892e75c4f24d8e71b41cfb9a81a634b90e6238443a813a3d34'
cipher_2 = 'de328f76159108f7653a5883decb8dec06b0fd9bc8d0dd7dade1f04836b8a07da20bfe70'

enc_bytes = unhex(enc_info)
cipher_1_bytes = unhex(cipher_1)
cipher_2_bytes = unhex(cipher_2)

#print(enc_bytes)
#print(cipher_1_bytes)
#print(cipher_2_bytes)

result = []

### [+] Decrypting starts here

for i, j in enumerate(enc_bytes):
    result.append(j ^ cipher_1_bytes[i] ^ cipher_2_bytes[i])

log.success(result)
flag = ""
for i in result:
    flag += chr(i)

log.success(flag)

1. Got the flag!

Flag

REDACTED

Lessons Learned

1. Identify the weakness from source review or fingerprinting first.
2. Iterate with incremental payloads instead of guessing.
3. Reuse the same pattern in future engagements.