Full solution is found [here](https://github.com/happysox/CTF_Writeups/tree/master/RITSEC_CTF_2018/reverseme) (co-author [ludvigknutsmark](https://github.com/ludvigknutsmark))

TLDR:

* In the binary the plaintext has been replaced with XXXXXXXXXXXXXXXX
* In the core dump the key has been replaced with YYYYYYYYYYYYYYYY

Solution:
Decrypt the ciphertext from the core dump with the key found in the binary

```python
#!/usr/bin/python2
from Crypto.Cipher import AES
from binascii import unhexlify

def decrypt(key, cipher_text):
aes = AES.new(key)
plaintext = aes.decrypt(cipher_text[:16])
return plaintext

cipher_text = unhexlify("a629fc7035ccd2df99fb42ebc25e4f9f")
print decrypt("ITSTHECRYPTOKEY!", cipher_text)
```

```
$ ./solution.py
RITSEC{AESISFUN}
```

Original writeup (https://github.com/happysox/CTF_Writeups/tree/master/RITSEC_CTF_2018/reverseme).