How to remediate – QMTP/QMQP Server Detection

1. Introduction

A QMTP/QMQP server is running on this port. QMTP is a proposed replacement for SMTP, developed by D.J. Bernstein. This indicates an unusual service is present which may be unexpected and could represent a misconfiguration or attempted circumvention of standard email protocols. A successful exploit could allow unauthorized message relaying or data interception. Confidentiality, integrity, and availability are all potentially at risk.

2. Technical Explanation

This vulnerability indicates the presence of a QMTP/QMQP server listening on a network port. Nessus currently only performs SMTP tests, so detection relies on identifying this alternative protocol. Exploitation is not directly tested by standard tools and requires specific knowledge of the QMTP/QMQP protocols. There are no known CVEs associated with simply *running* a QMTP/QMQP server; risk arises from its potential misuse.

• Root cause: The presence of an unintended or unmanaged service (QMTP/QMQP) on the network.
• Exploit mechanism: An attacker could potentially use the server to relay spam, intercept legitimate email traffic, or launch other attacks depending on the server’s configuration and access controls.
• Scope: Any system running a QMTP/QMQP server is affected. This is likely limited to systems where someone has specifically installed this software.

3. Detection and Assessment

Confirming whether a system is vulnerable involves identifying the presence of the QMTP/QMQP service on network ports.

• Quick checks: Use netstat -tulnp or ss -tulnp to list listening ports and identify any processes associated with QMTP/QMQP.
• Scanning: Nessus may flag this as an informational finding during a standard port scan. Other network scanners can be used, but specific signatures are unlikely.
• Logs and evidence: Check application logs for references to QMTP or QMQP, though these are unlikely unless the server is actively handling traffic.

netstat -tulnp | grep qmtp

4. Solution / Remediation Steps

The following steps outline how to remove a QMTP/QMQP server from a system.

4.1 Preparation

• Change window: This change requires minimal downtime but should be scheduled during a maintenance window. Approval may be needed from the system owner.

4.2 Implementation

1. Step 1: Identify the package name for QMTP/QMQP using your operating system’s package manager (e.g., apt list --installed | grep qmtp on Debian/Ubuntu).
2. Step 2: Remove the identified package using the appropriate command (e.g., sudo apt remove on Debian/Ubuntu).
3. Step 3: Verify that the QMTP/QMQP service is no longer running with netstat -tulnp or ss -tulnp.

4.3 Config or Code Example

This vulnerability does not involve a configuration file; it concerns an installed package.

Before

# Package is present (example output from apt list --installed)
qmtp-server/now 1.2.3 amd64 [installed]

After

# Package is removed (example output from apt list --installed)
# No qmtp packages listed.

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue.

• Practice 1: Least privilege – only install software that is absolutely necessary for the system’s function, reducing the attack surface.
• Practice 2: Regular vulnerability scanning – identify unexpected services running on your network.

4.5 Automation (Optional)

No automation script is provided as removal depends heavily on the package manager and operating system.

5. Verification / Validation

Confirming the fix involves verifying that the QMTP/QMQP service is no longer listening on any ports.

• Post-fix check: Run netstat -tulnp or ss -tulnp and confirm there are no processes associated with QMTP/QMQP. Expected output will not show any lines containing “qmtp”.
• Re-test: Re-run the initial scan to ensure the vulnerability is no longer detected.
• Smoke test: Verify that core system services (e.g., SSH, web server) are still functioning as expected.
• Monitoring: Monitor network traffic for unexpected connections on non-standard ports.

netstat -tulnp | grep qmtp

6. Preventive Measures and Monitoring

Preventive measures include maintaining a secure baseline configuration.

• Baselines: Update your security baseline to explicitly disallow the installation of QMTP/QMQP unless specifically required by business needs.
• Pipelines: Implement software inventory tools that flag unexpected packages or services installed on systems.
• Asset and patch process: Review system configurations regularly for unauthorized software installations.

7. Risks, Side Effects, and Roll Back

Removing the QMTP/QMQP server may disrupt applications relying on it.

• Risk or side effect 1: Applications dependent on QMTP/QMQP will be affected. Mitigation involves restoring from a snapshot or reinstalling the package if necessary.
• Roll back: Restore the system from the pre-change snapshot or backup. Reinstall the QMTP/QMQP package using your operating system’s package manager (e.g., sudo apt install on Debian/Ubuntu).

8. References and Resources

Resources related to this vulnerability are limited due to its informational nature.

• Vendor advisory or bulletin: Not applicable, as this is not a typical vendor-supplied vulnerability.
• NVD or CVE entry: No associated CVE entries exist for simply running the service.
• Product or platform documentation relevant to the fix: Documentation for your specific operating system’s package manager (e.g., apt, yum, dnf).