1. Introduction
ezbounce Detection identifies instances of the ezbounce IRC bouncer running on a system. ezbounce proxies communications between IRC clients and servers, which can be used to mask client addresses or allow connections from networks without direct access. While legitimate use is rare, attackers often install these tools to control botnets and evade detection. This vulnerability poses a low risk to confidentiality, integrity, and availability if the software is not authorized.
2. Technical Explanation
ezbounce is an IRC bouncer that allows persistent connections to IRC servers. Attackers use it as a proxy to hide their command-and-control infrastructure for botnets. The presence of ezbounce suggests potential unauthorized activity and compromise. An attacker could exploit this by using the bouncer to control compromised systems remotely.
- Root cause: Unauthorised installation of IRC bouncer software.
- Exploit mechanism: Attackers install ezbounce on compromised systems, then use it as a proxy for botnet communications.
- Scope: Linux systems are commonly affected.
3. Detection and Assessment
Confirming the presence of ezbounce can be done with quick port checks or more thorough process inspection.
- Quick checks: Use
netstat -tulnp | grep :6667to check if a process is listening on the default IRC bouncer port (6667). - Scanning: Nessus plugin ID 10389 can detect ezbounce. This is an example only, and may require updates.
- Logs and evidence: Check system logs for processes named ‘ezbounce’ or related configuration files in /etc/ directory.
netstat -tulnp | grep :66674. Solution / Remediation Steps
Ensure the use of ezbounce aligns with your organization’s security policy. If unauthorized, remove it.
4.1 Preparation
- Dependencies: None. Roll back plan is to restore from backup.
- Change window: Standard change control process may be required.
4.2 Implementation
- Step 1: Identify the ezbounce process ID using
ps aux | grep ezbounce. - Step 2: Terminate the ezbounce process with
kill. - Step 3: Remove the ezbounce executable and configuration files (e.g., from /usr/local/bin or /etc/). Use
rm -rf /path/to/ezbounce*.
4.3 Config or Code Example
No config or code example is applicable, as the remediation involves removing the software.
4.4 Security Practices Relevant to This Vulnerability
- Least privilege: Restrict user access to prevent unauthorized software installation.
- Software inventory: Maintain an accurate list of installed software to identify rogue applications.
4.5 Automation (Optional)
No automation is recommended due to the risk of removing legitimate system components.
5. Verification / Validation
Confirm removal by checking for running processes and associated files.
- Post-fix check: Run
ps aux | grep ezbounce; no output should be returned. - Re-test: Re-run the quick check from section 3 (
netstat -tulnp | grep :6667) to confirm port is closed. - Monitoring: Monitor system logs for any attempts to reinstall ezbounce.
ps aux | grep ezbounce6. Preventive Measures and Monitoring
Regularly review installed software and enforce a strict application control policy.
- Baselines: Update security baselines to include a list of prohibited software, including IRC bouncers.
- Pipelines: Implement application whitelisting or blacklisting in deployment pipelines.
- Asset and patch process: Conduct regular audits of installed software on all systems.
7. Risks, Side Effects, and Roll Back
Removing ezbounce may disrupt legitimate IRC connections if it is used for authorized purposes.
- Roll back: Restore the system from backup if unintended consequences occur.
8. References and Resources
- Vendor advisory or bulletin: http://www.linuxftw.com/ezbounce/
- NVD or CVE entry: Not applicable, as this is a detection of unauthorized software.
- Product or platform documentation relevant to the fix: https://en.wikipedia.org/wiki/Bouncer_(networking)