pam_krb5 authenticates a user by essentially running kinit with the password, getting a ticket-granting ticket (tgt) from the Kerberos KDC (Key Distribution Center) over the network, as a way to verify the password. However, if a keytab is not provisioned on the system, pam_krb5 has no way to validate the response from the KDC, and essentially trusts the tgt provided over the network as being valid. In a non-default FreeBSD installation that leverages pam_krb5 for authentication and does not have a keytab provisioned, an attacker that is able to control both the password and the KDC responses can return a valid tgt, allowing authentication to occur for any user on the system.
The requirements for the product dictate the use of an established authentication algorithm, but the implementation of the algorithm is incorrect.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Freebsd | Freebsd | * | 12.4 (excluding) |
| Freebsd | Freebsd | 13.0 (including) | 13.1 (excluding) |
| Freebsd | Freebsd | 12.4 (including) | 12.4 (including) |
| Freebsd | Freebsd | 12.4-p1 (including) | 12.4-p1 (including) |
| Freebsd | Freebsd | 12.4-p2 (including) | 12.4-p2 (including) |
| Freebsd | Freebsd | 12.4-rc2-p1 (including) | 12.4-rc2-p1 (including) |
| Freebsd | Freebsd | 12.4-rc2-p2 (including) | 12.4-rc2-p2 (including) |
| Freebsd | Freebsd | 13.1 (including) | 13.1 (including) |
| Freebsd | Freebsd | 13.1-b1-p1 (including) | 13.1-b1-p1 (including) |
| Freebsd | Freebsd | 13.1-b2-p2 (including) | 13.1-b2-p2 (including) |
| Freebsd | Freebsd | 13.1-p1 (including) | 13.1-p1 (including) |
| Freebsd | Freebsd | 13.1-p2 (including) | 13.1-p2 (including) |
| Freebsd | Freebsd | 13.1-p3 (including) | 13.1-p3 (including) |
| Freebsd | Freebsd | 13.1-p4 (including) | 13.1-p4 (including) |
| Freebsd | Freebsd | 13.1-p5 (including) | 13.1-p5 (including) |
| Freebsd | Freebsd | 13.1-p6 (including) | 13.1-p6 (including) |
| Freebsd | Freebsd | 13.1-p7 (including) | 13.1-p7 (including) |
| Freebsd | Freebsd | 13.1-rc1-p1 (including) | 13.1-rc1-p1 (including) |
| Freebsd | Freebsd | 13.2 (including) | 13.2 (including) |
| Libpam-krb5 | Ubuntu | bionic | * |
| Libpam-krb5 | Ubuntu | kinetic | * |
| Libpam-krb5 | Ubuntu | lunar | * |
| Libpam-krb5 | Ubuntu | mantic | * |
| Libpam-krb5 | Ubuntu | trusty | * |
| Libpam-krb5 | Ubuntu | trusty/esm | * |
| Libpam-krb5 | Ubuntu | xenial | * |
| Sssd | Ubuntu | bionic | * |
| Sssd | Ubuntu | kinetic | * |
| Sssd | Ubuntu | lunar | * |
| Sssd | Ubuntu | mantic | * |
| Sssd | Ubuntu | trusty | * |
| Sssd | Ubuntu | xenial | * |