OpenVPN version 2.3.12 and newer is vulnerable to unauthenticated Denial of Service of server via received large control packet. Note that this issue is fixed in 2.3.15 and 2.4.2.
Weakness
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Openvpn | Openvpn | 2.3.12 (including) | 2.3.12 (including) |
| Openvpn | Openvpn | 2.3.13 (including) | 2.3.13 (including) |
| Openvpn | Openvpn | 2.3.14 (including) | 2.3.14 (including) |
| Openvpn | Openvpn | 2.4.0 (including) | 2.4.0 (including) |
| Openvpn | Openvpn | 2.4.0-alpha2 (including) | 2.4.0-alpha2 (including) |
| Openvpn | Openvpn | 2.4.0-beta1 (including) | 2.4.0-beta1 (including) |
| Openvpn | Openvpn | 2.4.0-beta2 (including) | 2.4.0-beta2 (including) |
| Openvpn | Openvpn | 2.4.0-rc1 (including) | 2.4.0-rc1 (including) |
| Openvpn | Openvpn | 2.4.0-rc2 (including) | 2.4.0-rc2 (including) |
| Openvpn | Openvpn | 2.4.1 (including) | 2.4.1 (including) |
| Openvpn | Ubuntu | upstream | * |
| Openvpn | Ubuntu | zesty | * |
Extended Description
While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.
Potential Mitigations
References
- http://www.securityfocus.com/bid/98444
- http://www.securitytracker.com/id/1038473
- https://community.openvpn.net/openvpn/wiki/QuarkslabAndCryptographyEngineerAudits
- https://www.exploit-db.com/exploits/41993/
- http://www.securityfocus.com/bid/98444
- http://www.securitytracker.com/id/1038473
- https://community.openvpn.net/openvpn/wiki/QuarkslabAndCryptographyEngineerAudits
- https://www.exploit-db.com/exploits/41993/