1. Introduction
The Caldera ‘cdir’ Parameter Absolute Path Directory Traversal vulnerability is a flaw in the PHP script used by Caldera installations. A remote, unauthenticated attacker can exploit this to access arbitrary directories on the affected server. This could lead to confidential data disclosure and potential system compromise. Systems running vulnerable versions of Caldera are at risk. Impact is likely to be high on confidentiality, medium on integrity, and low on availability.
2. Technical Explanation
The vulnerability occurs because the ‘/dirmng/index.php’ script does not properly validate user-supplied input for the ‘cdir’ parameter. This allows an attacker to manipulate the path used by the script, potentially accessing files outside of the intended directory. The CVE assigned to this issue is CVE-2014-2933. An example attack involves sending a crafted HTTP request with a malicious ‘cdir’ value.
- Root cause: Missing input validation on the ‘cdir’ parameter in the ‘/dirmng/index.php’ script.
- Exploit mechanism: An attacker sends a specially crafted request to ‘/dirmng/index.php’, including a malicious ‘cdir’ value containing path traversal characters (e.g., ‘../’). This allows them to access files outside of the intended directory. For example, an attacker could attempt to read /etc/passwd by setting cdir to ‘../’ repeated enough times to reach the root directory and then accessing sensitive files.
- Scope: Caldera installations using vulnerable versions of the PHP script are affected.
3. Detection and Assessment
To confirm vulnerability, check the version of Caldera installed or scan for the specific signature. Review logs for suspicious requests to ‘/dirmng/index.php’.
- Quick checks: Check the application version in the web interface if available.
- Scanning: Nessus ID 67258 can detect this vulnerability, but may require updated plugins. Other scanners may also have signatures for CVE-2014-2933.
- Logs and evidence: Examine web server logs for requests to ‘/dirmng/index.php’ with unusual ‘cdir’ parameters. Look for patterns like ‘../’ or other path traversal sequences.
# Example command placeholder:
# No specific command available, check application version in the UI.
4. Solution / Remediation Steps
Currently there is no known solution to this vulnerability. Mitigation focuses on restricting access and monitoring for exploitation attempts.
4.1 Preparation
- Ensure you have a rollback plan in case of issues. A simple rollback would be to restore from backup.
- A change window may be needed depending on your environment and risk tolerance. Approval from security team is recommended.
4.2 Implementation
- Step 1: Implement strict access controls to limit who can access the Caldera installation.
- Step 2: Monitor web server logs for suspicious activity, specifically requests to ‘/dirmng/index.php’.
- Step 3: Consider using a Web Application Firewall (WAF) to block malicious requests containing path traversal sequences.
4.3 Config or Code Example
Before
# No code example available as there is no known patch. The vulnerability lies in the lack of input validation within the PHP script.
After
# No code example available as there is no known patch. Focus on WAF rules and access control.
4.4 Security Practices Relevant to This Vulnerability
Practices that directly address this vulnerability type include least privilege, input validation, and regular security monitoring.
- Practice 1: Least privilege can reduce the impact if an attacker gains access by limiting what they can do on the system.
- Practice 2: Input validation is crucial to prevent attackers from injecting malicious data into applications.
4.5 Automation (Optional)
No automation script available as there is no patch.
# No automation script available.
5. Verification / Validation
Confirm the fix by monitoring logs for blocked requests and verifying access controls are in place. Perform a negative test to ensure path traversal attempts are unsuccessful.
- Post-fix check: Verify that requests containing path traversal sequences in the ‘cdir’ parameter are blocked by your WAF or other security measures.
- Re-test: Attempt to access restricted files using a crafted request with a malicious ‘cdir’ value. The attempt should be blocked.
- Smoke test: Ensure legitimate users can still access the core functionality of Caldera without issues.
- Monitoring: Monitor web server logs for requests to ‘/dirmng/index.php’ and alert on any suspicious activity or failed attempts.
# Post-fix command and expected output:
# Check WAF logs for blocked requests containing "../" in the 'cdir' parameter. Expected output should show blocked requests.
6. Preventive Measures and Monitoring
Update security baselines to include input validation requirements. Implement checks in CI/CD pipelines to scan for path traversal vulnerabilities.
- Baselines: Update your web application security baseline to require strict input validation on all user-supplied parameters.
- Pipelines: Add Static Application Security Testing (SAST) tools to your CI/CD pipeline to identify potential path traversal vulnerabilities in your code.
- Asset and patch process: Implement a regular vulnerability scanning schedule for Caldera installations.
7. Risks, Side Effects, and Roll Back
Implementing strict access controls may impact legitimate users if not configured correctly. A rollback involves restoring the original configuration.
- Risk or side effect 2: WAF rules might cause false positives. Mitigation is tuning the WAF rules to minimize disruption.
- Roll back: Restore from backup if issues occur. Revert any changes made to access controls or WAF configuration.
8. References and Resources
Links only to sources that match this exact vulnerability.
- Vendor advisory or bulletin: http://www.securityfocus.com/bid/67258
- NVD or CVE entry: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2014-2933
- Product or platform documentation relevant to the fix: No specific documentation available as there is no patch.