Vulnerability 1 – Use of Cryptographically Weak PRNG
- CVE-IDs: CVE-2019-5440
- CVSSv3 Vector: AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CVSS Base Score: 8.1
- CVSS Impact Subscore: 5.9
- CVSS Exploitability Subscore: 2.2
A use of Cryptographically Weak Pseudo-Random Number Generator (PRNG) vulnerability has been discovered in the generation of the token used for the password recovery functionality of Revive Adserver by HackerOne user paulos_. Such vulnerability could be used to gain access to existing user accounts, if the attacker has access to the password recovery URL and knows or can guess the email address associated to the target account.
An attacker could request a password reset for a known user account and exploit the usage of the weak uniqid() to guess what the generated password recovery token could be. If successful, they could set a new password and gain access to the account.
We strongly advise people to upgrade to the most recent 4.2.1 version of Revive Adserver.
In case that is not immediately feasible, we especially recommend to delete or block access to the www/admin/password-recovery.php script.
The security contact for Revive Adserver can be reached at: <security AT revive-adserver DOT com>
Please review https://www.revive-adserver.com/security/ before doing so.