Hack The Box / Challenges / Web / Emdee

This one I think it was the easiest.. I dont think it is actually a web challenge, instead it is a scripting challenge.

We see from the frontpage that a string is provided and we've to MD5 hash it then make a POST request with the MD5 hash. If we're quick enough (we can see by making a bunch of requests in sequence that the string remains for a short period of time like 2 seconds) to provide the hash before the string changes it will give us the flag.

I made the following python3 script to solve it.

    #!/usr/bin/env python
    import requests
    import re
    import hashlib

    params = { 'name': 'value' }
    headers = { 'Encoding'}

    url = "http://docker.hackthebox.eu:51334"
    s = requests.Session()
    req = s.get(url)

    t = req.text.split('\n')[5]

    regexp = re.compile(r"center'>([^<]*)")
    matches = regexp.findall(t)
    payload = matches[1]

    m = hashlib.md5()
    md5 = m.hexdigest()

    print("md5(%s) = %s" % (payload,md5))

    data = {'hash': md5}
    req = s.post(url, data=data)


Running will give us:

    $ python3 solve.py 
    md5(LAy3AtGYByKR6Ylc6rkp) = 1a5bed4c898a16c41e7d8bcf7b3adfe2
    <title>emdee five for life</title>
    <body style="background-color:powderblue;">
    <h1 align='center'>MD5 encrypt this string</h1><h3 align='center'>LAy3AtGYByKR6Ylc6rkp</h3><p align='center'>HTB{N1c3_ScrIpt1nG_B0i!}</p><center><form action="" method="post">
    <input type="text" name="hash" placeholder="MD5" align='center'></input>
    <input type="submit" value="Submit"></input>

That's it. No black magic thinking in this one.

jemos / Sep, 26 2019