Use of a Broken or Risky Cryptographic Algorithm in mautic/mauticValid
Jul 10th 2021
mt_rand is used to generate session tokens, this function is cryptographically flawed due to its nature being one pseudorandomness, an attacker can take advantage of the cryptographically insecure nature of this function to enumerate session tokens for accounts that are not under his/her control
🕵️♂️ Proof of Concept
Numerous examples and attack implementations can be found in this paper .
If you're looking for a practical tool that can crack your
mt_rand implementation's seed value, see this project and run the following commands in a console with
php5 and OpenWall's tool installed:
root$ php -r 'mt_srand(13333337); echo mt_rand( ), "\n";'
After that, copy the output (
1863134308) and execute the following commands:
root$ gcc php_mt_seed.c -o php_mt_seed root$ ./php_mt_seed 1863134308
After waiting ~1 minute you should have a few possible seeds corresponding to their PHP versions, next to your installed PHP version you should see something akin to:
seed = 0x00cb7359 = 13333337 (PHP 7.1.0+)
Hey, that's your seed!
An attacker could takeover accounts at random by enumerating and using access tokens.