#VU6544 Denial of service in OpenVPN for Windows - CVE-2017-7478

Vulnerability identifier: #VU6544

Vulnerability risk: Medium

CVSSv4.0: 5.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/U:Green]

CVE-ID: CVE-2017-7478

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
OpenVPN for Windows
Client/Desktop applications / Software for system administration

Vendor: OpenVPN

Description
The vulnerability allows a remote authenticated attacker to cause DoS conditions on the target system.

The weakness exists due to improper user-input validation. A remote attacker can send a specially crafted P_CONTROL packet and cause the OpenVPN server process to stop running due to an ASSERT() exception.

Successful exploitation of the vulnerability results in denial of service.

Mitigation
Update to version 2.3.15, 2.4.2 or later.

Vulnerable software versions

OpenVPN for Windows: 2.3.12 - 2.3.14, 2.4.0 - 2.4.1

---

External links
https://community.openvpn.net/openvpn/wiki/QuarkslabAndCryptographyEngineerAudits

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated user via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability. However, proof of concept for this vulnerability is available.