A flaw was found in Samba. It is susceptible to a vulnerability where multiple incompatible RPC listeners can be initiated, causing disruptions in the AD DC service. When Sambas RPC server experiences a high load or unresponsiveness, servers intended for non-AD DC purposes (for example, NT4-emulation classic DCs) can erroneously start and compete for the same unix domain sockets. This issue leads to partial query responses from the AD DC, causing issues such as The procedure number is out of range when using tools like Active Directory Users. This flaw allows an attacker to disrupt AD DC services.
The product does not properly control the allocation and maintenance of a limited resource.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Samba | Samba | * | 4.17.12 (excluding) |
| Samba | Samba | 4.18.0 (including) | 4.18.8 (excluding) |
| Samba | Samba | 4.19.0 (including) | 4.19.1 (excluding) |
| Samba | Ubuntu | bionic | * |
| Samba | Ubuntu | devel | * |
| Samba | Ubuntu | jammy | * |
| Samba | Ubuntu | lunar | * |
| Samba | Ubuntu | mantic | * |
| Samba | Ubuntu | trusty | * |
| Samba | Ubuntu | xenial | * |
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.