CVE-2021-27913: Use of a Broken or Risky Cryptographic Algorithm

✍️ Description The function mtrand 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 mtrand 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 'mtsrand(13333337); echo mtrand( ), "\n";' After that, copy the output (1863134308) and execute the following commands:

root$ gcc phpmtseed.c -o phpmtseedroot$ ./phpmtseed 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!

💥 Impact An attacker could takeover accounts at random by enumerating and using access tokens.

📝 References

- https://openwall.com/phpmtseedhttps://crypto.di.uoa.gr/CRYPTO.SEC/RandomnessAttacksfiles/paper.pdf - https://github.com/mautic/mautic/blob/5213e320b4ef4d0c51bb84c1d46a1071e8e4f7fc/app/bundles/PointBundle/Controller/TriggerController.php#L187 - https://github.com/mautic/mautic/releases/tag/3.3.4 - https://github.com/mautic/mautic/releases/tag/4.0.0