WRITEUP.md

General Skills Quiz Write Up

The General Skills Quiz is meant to be a beginner challenge in order to learn how to manipulate strings in Python using the commonly known pwntools library.

There are 11 challenges in total and then you will receive the flag.

The solve script that I have written is listed below.

Please excuse my terrible code.

# /usr/bin/python3
import re, urllib.parse, base64, codecs
from pwn import *

def extract_q():
    print(r.recvuntil(":").decode('utf-8'))
    q = str(r.recvline().strip())
    q_extracted = "".join(re.findall("'([^']*)'", q))
    return q_extracted

def answer_send(ans, n):
    answer = ans
    print("[+] Answer " + str(n) +": " + answer)
    r.sendline(answer)

# Question 1 - Basic Maths
r = remote('127.0.0.1', 1337)
print(r.recvline().decode('utf-8'))
# Sending \n to progress
r.sendline()
print(r.recvline().decode('utf-8'))
print(r.recvline().decode('utf-8'))
answer_send("2", 1)

# Question 2 - Hex -> Base 10
answer_send(str(int(extract_q(), 0)), 2)

# Question 3 - Hex -> ASCII
answer_send(bytes.fromhex(extract_q()).decode('utf-8'), 3)

# Question 4 - URL Encoded -> ASCII Symbols
answer_send(urllib.parse.unquote(extract_q()), 4)

# Question 5 - Base64 -> ASCII
answer_send(base64.b64decode(extract_q()).decode('utf-8'), 5)

# Question 6 - ASCII -> Base64
answer_send(base64.b64encode(str.encode(extract_q())).decode('utf-8'), 6)

# Question 7 - ROT13 -> ASCII
answer_send(codecs.encode(extract_q(), 'rot_13'), 7)

# Question 8 - ASCII -> ROT13
answer_send(codecs.decode(extract_q(), 'rot_13'), 8)

# Question 9 - Binary -> Base 10
answer_send(str(int(extract_q(),2)), 9)

# Question 10 - Base10 -> Binary
answer_send(bin(int(extract_q())), 10)

# Question 11 - CTF Q
print(r.recvuntil("?"))
answer11 = "DUCTF"
print("[+] Answer 11: " + answer11)
r.sendline(answer11)
print(r.recvall().decode('utf-8'))