A flaw was found in 389 Directory Server. The PBKDF2-SHA256 password storage plugin does not enforce an upper bound on the iteration count extracted from stored password hashes. A privileged attacker who can modify a users password hash can cause excessive CPU consumption during authentication, resulting in denial of service.
Weakness
The product does not properly control the allocation and maintenance of a limited resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Directory_server | Redhat | 11.0 (including) | 11.0 (including) |
| Directory_server | Redhat | 12.0 (including) | 12.0 (including) |
| Directory_server | Redhat | 13.0 (including) | 13.0 (including) |
| 389_directory_server | Redhat | 1.3.6.0 (including) | 1.3.6.0 (including) |
| Enterprise_linux | Redhat | 7.0 (including) | 7.0 (including) |
| Enterprise_linux | Redhat | 8.0 (including) | 8.0 (including) |
| Enterprise_linux | Redhat | 9.0 (including) | 9.0 (including) |
| Enterprise_linux | Redhat | 10.0 (including) | 10.0 (including) |
Potential Mitigations
Mitigation of resource exhaustion attacks requires that the target system either:
The first of these solutions is an issue in itself though, since it may allow attackers to prevent the use of the system by a particular valid user. If the attacker impersonates the valid user, they may be able to prevent the user from accessing the server in question.
The second solution is simply difficult to effectively institute – and even when properly done, it does not provide a full solution. It simply makes the attack require more resources on the part of the attacker.
Related Attack Patterns
- https://cwe.mitre.org/data/definitions/147.html
- https://cwe.mitre.org/data/definitions/227.html
- https://cwe.mitre.org/data/definitions/492.html