How to remediate – Owl Intranet Engine lib/OWL_API.php xrms_file_root Parameter R…

1. Introduction

Owl Intranet Engine lib/OWL_API.php contains a remote file include vulnerability in the ‘xrms_file_root’ parameter. This allows an attacker to potentially view arbitrary files on a server, or execute PHP code remotely. Systems running Owl Intranet Engine are affected. Successful exploitation could lead to confidentiality, integrity and availability loss.

2. Technical Explanation

• Exploit mechanism: An attacker can send a crafted request to include a malicious file, for example by setting ‘xrms_file_root’ to a path containing a PHP payload or sensitive system files.
• Scope: Owl Intranet Engine is affected. Specific versions are not detailed in the available information.

3. Detection and Assessment

Confirming vulnerability requires checking for the presence of the vulnerable script and potentially testing its behaviour. A thorough scan will identify exposed instances.

• Quick checks: Check for the existence of ‘lib/OWL_API.php’ on the server using a file system listing tool or web browser access attempt.
• Scanning: Nessus vulnerability ID b9b72209 may detect this issue. Other scanners with updated signatures might also identify it.
• Logs and evidence: Examine web server logs for requests accessing ‘lib/OWL_API.php’ with suspicious ‘xrms_file_root’ parameters.

ls -l /path/to/owl/intranet/engine/lib/OWL_API.php

4. Solution / Remediation Steps

Currently, a specific solution is not known. The following steps outline general best practices to mitigate risk while awaiting an official patch.

4.1 Preparation

• No services need to be stopped, but monitor resource usage during testing. A roll back plan involves restoring from backup or snapshot.
• Changes should be approved by a senior administrator.

4.2 Implementation

1. Step 1: Implement strict input validation on the ‘xrms_file_root’ parameter to prevent inclusion of arbitrary files. Whitelisting allowed paths is recommended.
2. Step 2: If possible, restrict access to the ‘lib/OWL_API.php’ script to only trusted users or IP addresses using web server configuration.
3. Step 3: Monitor logs for any suspicious activity related to file inclusion attempts.

4.3 Config or Code Example

Before

After

4.4 Security Practices Relevant to This Vulnerability

Several security practices can help prevent this type of vulnerability.

• Practice 1: Input validation is crucial to block malicious data from reaching the application logic.
• Practice 2: Least privilege limits the impact if an attacker gains access, reducing potential damage.

4.5 Automation (Optional)

Automation is not directly applicable without a known patch or configuration change. Consider using web application firewalls to block malicious requests.

5. Verification / Validation

• Post-fix check: Attempt to include a file outside of the allowed paths via a crafted request. The server should return an error message or deny access.
• Re-test: Re-run the earlier detection methods (file listing, web server logs) to confirm that malicious requests are blocked.
• Smoke test: Verify that legitimate users can still access and use the Owl Intranet Engine functionality.
• Monitoring: Monitor web server logs for any attempts to include files outside of allowed paths.

curl 'http://example.com/lib/OWL_API.php?xrms_file_root=/etc/passwd' -I

6. Preventive Measures and Monitoring

Regular security assessments and updates are important for preventing this type of vulnerability.

• Baselines: Update a web server baseline to include input validation rules and access restrictions.
• Pipelines: Incorporate static application security testing (SAST) into the development pipeline to identify vulnerable code patterns.
• Asset and patch process: Implement a regular patch review cycle for all software, including Owl Intranet Engine.

7. Risks, Side Effects, and Roll Back

Implementing input validation may cause compatibility issues with existing functionality if not carefully tested.

• Risk or side effect 1: Incorrectly configured input validation could block legitimate requests. Thorough testing is required.
• Risk or side effect 2: Access restrictions might impact users who legitimately need access to certain files.
• Roll back: Restore the Owl Intranet Engine installation from backup or snapshot if issues occur. Revert any changes made to web server configuration.

8. References and Resources

• Vendor advisory or bulletin: No official vendor advisory is currently available.
• NVD or CVE entry: CVE-2006-1149
• Product or platform documentation relevant to the fix: No specific documentation is available for this vulnerability.