1. Introduction
The IBM WebSphere Portal Unspecified HTTP Response Splitting vulnerability (PM85…) allows an attacker to inject arbitrary HTTP headers, potentially manipulating cookies and other session data. This could lead to account takeover or other unauthorized actions. Affected systems are typically web servers running the WebSphere Portal software on Windows. A successful exploit could compromise the confidentiality, integrity, and availability of user sessions.
2. Technical Explanation
The vulnerability stems from insufficient input validation when handling HTTP requests. An attacker can craft a malicious request that includes specially formatted headers which are then incorrectly processed by WebSphere Portal, leading to header injection. This allows them to add or modify HTTP response headers. CVE-2013-2950 describes this issue.
- Root cause: Missing input validation on HTTP request headers.
- Exploit mechanism: An attacker sends a crafted HTTP request with malicious headers that are not properly sanitized, allowing for arbitrary header injection. For example, an attacker could inject a ‘Set-Cookie’ header to hijack user sessions.
- Scope: WebSphere Portal versions 6.1.0.x / 6.1.5.x CF26, 7.0.0.2 CF21 and 8.0.0.x CF05 are affected.
3. Detection and Assessment
To confirm vulnerability, check the WebSphere Portal version installed on your systems. A thorough assessment involves analyzing HTTP request/response headers for anomalies.
- Quick checks: Use the IBM Installation Manager GUI or command line to determine the WebSphere Portal version.
- Scanning: Nessus plugin ID 65a35990 can be used as an example scanner detection method.
- Logs and evidence: Examine web server logs for unusual HTTP header activity, particularly ‘Set-Cookie’ headers that were not expected.
4. Solution / Remediation Steps
Apply the appropriate fix from IBM to address this vulnerability. Follow these steps carefully.
4.1 Preparation
- Ensure you have sufficient disk space for the update process. A roll back plan involves restoring from the pre-update backup if issues occur.
- A change window may be required, depending on service criticality and downtime tolerance. Approval from system owners is recommended.
4.2 Implementation
- Step 1: Download and install APAR PM85071 from the IBM Support website.
- Step 2: Apply the fix for your specific WebSphere Portal version (6.1.0.x / 6.1.5.x CF26, 7.0.0.2 CF21 or 8.0.0.x CF05).
4.3 Config or Code Example
Before
After
4.4 Security Practices Relevant to This Vulnerability
Several security practices can mitigate this type of vulnerability.
- Practice 1: Input validation is crucial to prevent malicious data from being processed by web applications.
- Practice 2: Implement a patch management process to ensure timely application of security updates and fixes.
4.5 Automation (Optional)
5. Verification / Validation
- Post-fix check: Use the IBM Installation Manager GUI or command line to confirm the updated version is installed.
- Re-test: Run Nessus plugin ID 65a35990 again; it should no longer report the vulnerability.
- Monitoring: Monitor web server logs for any unexpected HTTP header activity, particularly ‘Set-Cookie’ headers.
6. Preventive Measures and Monitoring
Implement security baselines and CI/CD pipeline checks to prevent similar vulnerabilities.
- Baselines: Update your WebSphere Portal security baseline to include the latest patch requirements.
- Pipelines: Integrate SAST or DAST tools into your CI/CD pipeline to identify potential input validation issues during development.
- Asset and patch process: Establish a regular patch review cycle for all web applications, including WebSphere Portal.
7. Risks, Side Effects, and Roll Back
Applying the patch may require downtime. A roll back plan is essential.
- Risk or side effect 1: Downtime during patching. Mitigation: Schedule patching during off-peak hours.
- Risk or side effect 2: Compatibility issues with custom applications. Mitigation: Test the patch in a non-production environment first.
- Roll back: Restore from the pre-update backup of your WebSphere Portal configuration. Restart all services.
8. References and Resources
- Vendor advisory or bulletin: https://www-304.ibm.com/support/docview.wss?uid=swg21638864
- NVD or CVE entry: CVE-2013-2950
- Product or platform documentation relevant to the fix: IBM WebSphere Portal documentation.