How to remediate – YIFF Sound Server Detection

1. Introduction

The YIFF Sound Server Detection vulnerability indicates a network sound server is running on a remote host. This software, while open source, may introduce security risks if its use isn’t controlled and aligned with organisational policies. Systems typically affected are those hosting audio streaming services or applications requiring network-based sound transmission. A successful compromise could lead to information disclosure or denial of service.

2. Technical Explanation

The vulnerability arises from the presence of a YIFF sound server listening on a network port, potentially exposing it to unwanted access. An attacker could connect to this server and exploit any vulnerabilities within the software itself. The main precondition is network connectivity to the affected host and the open port.

• Root cause: The presence of an unapproved or misconfigured YIFF sound server on the network.
• Exploit mechanism: An attacker could attempt to connect to the server, enumerate its capabilities, and potentially exploit known vulnerabilities within the YIFF software. For example, they might send specially crafted audio data to trigger a buffer overflow or other flaw.
• Scope: Systems running any version of the YIFF sound server are affected.

3. Detection and Assessment

Confirming whether a system is vulnerable involves checking for the presence of the listening service. A quick check can identify if the port is open, while more thorough methods involve identifying the software version.

• Quick checks: Use `netstat -tulnp` or `ss -tulnp` to list listening ports and associated processes. Look for a process named “yiff” or listening on non-standard audio ports.
• Scanning: Nessus plugin ID 16834 can detect the YIFF sound server, but results should be verified manually.
• Logs and evidence: System logs may show the startup of the YIFF service. Check for entries related to “yiff” or the port it’s listening on.

netstat -tulnp | grep yiff

4. Solution / Remediation Steps

Fixing this issue requires ensuring that use of YIFF sound server aligns with security policies, and potentially removing or securing the software.

4.1 Preparation

• Dependencies: Ensure no critical applications rely on the YIFF sound server. A roll back plan involves restoring from the snapshot or reinstalling the affected service.
• Change window: This change may require a maintenance window depending on system criticality and dependencies; approval from the IT manager is recommended.

4.2 Implementation

1. Step 1: Review your organisation’s acceptable use policy to determine if YIFF sound server usage is permitted.
2. Step 2: If not permitted, stop the YIFF service using `systemctl stop yiff` or equivalent for your operating system.
3. Step 3: Remove the YIFF package using your package manager (e.g., `apt remove yiff`, `yum remove yiff`).
4. Step 4: Verify that the service is no longer running and listening on any ports.

4.3 Config or Code Example

Before

systemctl status yiff

After

systemctl status yiff 
● yiff.service - YIFF Sound Server
   Inactive (dead)

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this issue. Least privilege reduces the impact of exploitation, while a robust patch management process ensures timely updates and removal of unapproved software.

• Practice 1: Implement least privilege principles to limit the access rights of any network services.
• Practice 2: Enforce a strict application whitelisting policy to prevent unauthorized software installation.

4.5 Automation (Optional)

#!/bin/bash
# Check if yiff is installed
if command -v yiff >/dev/null 2>&1; then
  echo "YIFF sound server found, removing..."
  apt remove -y yiff # Or yum remove -y yiff depending on the system
  systemctl stop yiff
fi

5. Verification / Validation

Confirming the fix involves verifying that the YIFF service is no longer running and listening on any ports. A negative test ensures that connections to the server are refused.

• Post-fix check: Run `netstat -tulnp | grep yiff`. The output should be empty, indicating the service is not listening.
• Re-test: Re-run the initial detection method (e.g., `netstat -tulnp`) to confirm no YIFF processes are present.
• Monitoring: Monitor system logs for any unexpected attempts to start the YIFF service.

netstat -tulnp | grep yiff

6. Preventive Measures and Monitoring

Updating security baselines and implementing application whitelisting can prevent this issue. A regular patch review cycle ensures timely removal of unapproved software.

• Baselines: Update your security baseline to include a check for unauthorized network services like YIFF sound server.
• Pipelines: Integrate static analysis tools into CI/CD pipelines to detect the presence of potentially vulnerable or unapproved software packages.
• Asset and patch process: Implement a monthly review cycle for installed software, focusing on removing any applications not explicitly approved by security teams.

7. Risks, Side Effects, and Roll Back

Removing YIFF sound server may impact applications that rely on it. A roll back involves restoring the system snapshot or reinstalling the service.

• Risk or side effect 2: Incorrect package removal could lead to broken dependencies; test thoroughly in a non-production environment first.
• Roll back: Restore the system snapshot taken prior to making changes, or reinstall the YIFF package using your package manager.

8. References and Resources

• Vendor advisory or bulletin: http://freshmeat.sourceforge.net/projects/yiff/