How to remediate – 3270 Mapper Service Detection

1. Introduction

The 3270 Mapper Service Detection identifies a deprecated RPC service running on your systems. This service is no longer actively maintained and could present a future security risk if vulnerabilities are discovered. Systems commonly affected are those with legacy application support requiring 3270 protocol access. A successful exploit could lead to remote code execution, impacting confidentiality, integrity, and availability.

2. Technical Explanation

The 3270 mapper RPC service is a component used for older terminal emulation protocols. It remains active on some systems due to legacy application dependencies. An attacker exploiting this service would likely attempt to execute arbitrary code remotely. The main precondition for exploitation is the service being exposed and accessible over the network.

• Root cause: The 3270 mapper RPC service is enabled by default on some older systems, even if not required.
• Exploit mechanism: An attacker could send malicious RPC requests to the service, potentially leading to code execution.
• Scope: Windows operating systems with legacy application support are affected.

3. Detection and Assessment

You can confirm whether a system is vulnerable by checking for the running 3270 mapper service. A quick check involves reviewing services, while a thorough method includes examining RPC endpoint configurations.

• Quick checks: Use the following command to list running services and look for “3270 Mapper Service”.
• Scanning: Nessus or other vulnerability scanners may identify this issue using signature ID 165849. This is an example only.
• Logs and evidence: Event logs may contain entries related to the service startup or RPC communication attempts.

sc query 3270mapper

4. Solution / Remediation Steps

Disable the 3270 mapper service if it is not required. This will remove the potential attack surface.

4.1 Preparation

• Ensure you have documented the dependencies of this service to avoid disruption. Roll back by re-enabling the service if issues occur.
• A change window may be needed depending on your environment and approval process.

4.2 Implementation

1. Step 1: Open the Services application (services.msc).
2. Step 2: Locate “3270 Mapper Service” in the list of services.
3. Step 3: Right-click on the service and select “Properties”.
4. Step 4: In the Properties window, change the Startup type to “Disabled”.
5. Step 5: Click “Apply”, then “OK”.

4.3 Config or Code Example

Before

Startup type: Automatic

After

Startup type: Disabled

4.4 Security Practices Relevant to This Vulnerability

• Practice 1: Least privilege – only enable services that are absolutely necessary, reducing the attack surface.

4.5 Automation (Optional)

# PowerShell example to disable the service
Set-Service -Name "3270Mapper" -StartupType Disabled

5. Verification / Validation

• Post-fix check: Run `sc query 3270mapper`. The output should indicate “STATE : STOPPED”.
• Re-test: Repeat the command from section 3. It should not list the 3270 Mapper Service.
• Smoke test: Verify any applications that previously used this service still function as expected (if applicable).
• Monitoring: Monitor event logs for errors related to the 3270 mapper service, which could indicate a regression.

sc query 3270mapper

6. Preventive Measures and Monitoring

• Baselines: Update your security baseline or policy to include disabling unnecessary services like this one.
• Pipelines: Include checks in your CI/CD pipeline to ensure that only necessary services are enabled on new systems.
• Asset and patch process: Review the list of running services regularly as part of your asset management process.

7. Risks, Side Effects, and Roll Back

• Roll back: Re-enable the “3270 Mapper Service” in the Services application (services.msc) and set the Startup type to Automatic.

8. References and Resources

• Vendor advisory or bulletin: IAVA 0001-A-0504