Service:
openvpn
Protocol:
UDPPort:
1194Used for:
A widely used open-source VPN solution that provides secure point-to-point or site-to-site connectionsWhy It’s Open
Port 1194 is the default port used by OpenVPN, a widely used open-source VPN solution that provides secure point-to-point or site-to-site connections. This port is used for encapsulating VPN traffic using SSL/TLS and is often found open on VPN gateways, remote access servers, and cloud infrastructure.
Common Risks
Although OpenVPN is generally secure when properly configured, leaving port 1194 exposed—especially with weak or default settings—can lead to:
- Brute-Force Attacks
Attackers may attempt to guess user credentials or client certificates if rate limiting or MFA is not enforced. - Information Disclosure:
Some OpenVPN servers may leak version information or reveal that OpenVPN is running, aiding reconnaissance. - Unauthorized Access:
If client certificates or authentication keys are stolen or misconfigured, attackers could gain access to internal networks. - Exploitable Vulnerabilities
Outdated OpenVPN versions may contain vulnerabilities such as buffer overflows or remote code execution flaws.
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Enumeration & Testing
Check if it’s open
nmap -sU -p 1194Use OpenVPN to test
openvpn --config client.ovpnBanner Grabbing
echo | nc -u -v 1194What to Look For
| Checkpoint | What it means |
|---|---|
| Port 1194 open externally | VPN is publicly reachable — verify security settings |
| No rate limiting | Susceptible to brute-force or DoS attempts |
| Self-signed or weak certs | May be vulnerable to MitM or trust issues |
| Outdated OpenVPN version | May contain known CVEs |
Mitigation
- Restrict Access
Allow port 1194 only from trusted IPs or regions using firewall rules. - Use Strong Authentication
Implement two-factor authentication and strong client certificate policies. - Keep OpenVPN Updated
Always use the latest stable release to patch known vulnerabilities - Enable TLS Auth (tls-auth or tls-crypt)
This adds an additional HMAC signature to packets, preventing unauthorized connections and some DoS attacks. - Monitor Logs and Connections
Regularly review connection logs to detect abnormal access attempts.
Known CVEs and Exploits
- CVE-2020-15078 – OpenVPN DoS via malformed control packet.
- CVE-2017-7521 – OpenVPN memory leak through push-peer-info.
- CVE-2014-8104 – Buffer overflow in OpenVPN leading to possible RCE.
- Exploit for CVE-2014-8104 – Proof-of-concept code for overflow vulnerability in OpenVPN.