CVE-2021-27913
Use of a Broken or Risky Cryptographic Algorithm
Description
## ✍️ Description The function 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_seedroot$ ./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! ## 💥 Impact An attacker could takeover accounts at random by enumerating and using access tokens. ## 📝 References - https://openwall.com/php_mt_seedhttps://crypto.di.uoa.gr/CRYPTO.SEC/Randomness_Attacks_files/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
How to fix CVE-2021-27913
To remediate CVE-2021-27913, upgrade the affected package to a fixed version below.
- —upgrade to 3.3.4 or later
Is CVE-2021-27913 being exploited?
Low — EPSS is 0.1%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 3.3.4