Werk #14482: Use proper HMAC for cookie signing
| Component | Setup | ||
| Title | Use proper HMAC for cookie signing | ||
| Date | Aug 2, 2022 | ||
| Level | Trivial Change | ||
| Class | Security Fix | ||
| Compatibility | Incompatible - Manual interaction might be required | ||
| Checkmk versions & editions |
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Previously to this Werk the Session cookies were signed with with calculating a SHA256 hash over username, session id, a serial plus a secret. This could in theory lead to a "partial message collision".
Since we parse the data given in the cookie and test for validity, we are confident that such an attack is not possible. But to be future-proof we switch to proper HMAC for signing the cookie value. This will invalidate all session cookies for a site. Therefore all users have to reauthenticate to retrieve new valid cookies.