Nice netcat...

• Description: There is a nice program that you can talk to by using this command in a shell: nc mercury.picoctf.net 21135, but it doesn't speak English...
• Difficulty: Easy

---

🔎 Solution

After establishing a connection to the server, we receive a series of numbers in decimal format.

┌──(kali㉿kali)-[~/Desktop]
└─$ nc mercury.picoctf.net 21135
112 
105 
99 
111 
67 
84 
70 
123 
103 
48 
48 
100 
95 
107 
49 
116 
116 
121 
33 
95 
110 
49 
99 
51 
95 
107 
49 
116 
116 
121 
33 
95 
97 
102 
100 
53 
102 
100 
97 
52 
125 
10

We then write a short Python script to convert these decimal numbers into their corresponding ASCII characters.

decimal_values = [
    112, 105, 99, 111, 67, 84, 70, 123, 103, 48,
    48, 100, 95, 107, 49, 116, 116, 121, 33, 95,
    110, 49, 99, 51, 95, 107, 49, 116, 116, 121,
    33, 95, 97, 102, 100, 53, 102, 100, 97, 52, 125
]
ascii_string = ''.join(chr(num) for num in decimal_values)
print(ascii_string)

Executing the script reveals the flag.

┌──(kali㉿kali)-[~/Desktop]
└─$ python script.py 
picoCTF{g00d_k1tty!_n1c3_k1tty!_afd5fda4}

🚩Flag

picoCTF{g00d_k1tty!_n1c3_k1tty!_afd5fda4}