SQ40105
Detected container images that might expose the Telnet port.
| priority | CI/CD status | severity | effort | RL level | RL assessment |
|---|---|---|---|---|---|
 | pass | high | medium | None | None |
About the issue
Containers are a simple, yet powerful approach to process and filesystem isolation. When configured correctly, a container runs a set of processes isolated from their host system. Containers typically run as executables or as services, but regardless of their use, they must be properly secured. Although Telnet might seem practical for administration, it is an insecure protocol that transmits unencrypted credentials, and can additionally increase the attack surface by providing an obvious entry point in an environment.
How to resolve the issue
- Avoid running remote access services such as Telnet.
- Check if there's a running Telnet daemon or service in the container's process list bound to port 23, or if one is executed on startup, and remove it.
Recommended reading
- Docker Expose Port: What It Means and What It Doesn't Mean (External resource - CloudBees)
- telnetd Daemon (External resource - IBM)
- Remote access service (External resource - Wikipedia)