1. Introduction
The Skull-Splitter Guestbook Multiple Field XSS vulnerability allows attackers to inject malicious scripts into the guestbook application. This can lead to the execution of arbitrary code within a user’s browser when viewing the compromised guestbook, potentially stealing cookies or redirecting users to harmful websites. Systems running the Skull-Splitter PHP guestbook software are affected. A successful attack could result in loss of system integrity and potential compromise of user accounts.
2. Technical Explanation
This vulnerability occurs because the Skull-Splitter guestbook does not properly sanitise user input submitted through the subject or message fields. This allows attackers to inject cross-site scripting (XSS) payloads that are then executed by other users’ browsers when they view the compromised content. The CVE identifier for this issue is CVE-2005-1620.
- Root cause: Missing input validation on subject and message fields in the PHP guestbook script.
- Exploit mechanism: An attacker submits a malicious script within the subject or message field of a guestbook entry. When another user views this entry, the script is executed in their browser. For example, submitting `` will display an alert box when viewed.
- Scope: Affected versions of the Skull-Splitter Guestbook PHP application are vulnerable.
3. Detection and Assessment
You can confirm a vulnerability by checking the version of the installed guestbook software, or attempting to inject a simple XSS payload.
- Quick checks: Check for the presence of Skull-Splitter Guestbook files on web servers.
- Scanning: Nessus plugin ID 13632 can detect this vulnerability. This is an example only and may require updating.
- Logs and evidence: Examine web server logs for requests containing suspicious characters in subject or message parameters.
# Example command placeholder:
# No specific command available, check file existence on the server
ls -l /path/to/skullsplitter/*
4. Solution / Remediation Steps
Currently there is no official solution for this vulnerability. Mitigation focuses on removing or replacing the vulnerable software.
4.1 Preparation
- Ensure you have a replacement application ready, or plan for complete removal of the guestbook functionality. A roll back plan is to restore the backed-up data and restart the web server.
- A change window may be required depending on your organisation’s policies. Approval from the security team might also be needed.
4.2 Implementation
- Step 1: Back up the Skull-Splitter Guestbook data directory.
- Step 2: Remove the Skull-Splitter Guestbook files from the web server.
- Step 3: Deploy a replacement guestbook application, or disable the functionality entirely.
4.3 Config or Code Example
Before
# No code example available, as the vulnerability is due to lack of sanitisation in the PHP script itself. The entire script needs replacing or removing.
After
# No code example available, as the solution involves removal/replacement of the vulnerable software.
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this type of issue.
- Practice 2: Least privilege limits the impact if an attacker does manage to exploit a vulnerability.
4.5 Automation (Optional)
No automation steps are available for this specific issue, as the recommended solution is removal of the vulnerable software.
# No script provided due to lack of a patch or automated fix.
5. Verification / Validation
Confirm that the Skull-Splitter Guestbook files have been removed and are no longer accessible via your web server. Attempt to access the guestbook functionality to verify it is disabled.
- Post-fix check: Verify that the Skull-Splitter Guestbook directory does not exist on the webserver using `ls -l /path/to/skullsplitter/*`. Expected output should be “No such file or directory”.
- Re-test: Attempt to access the guestbook URL. It should return a 404 error or redirect to another page.
- Smoke test: Verify that other web applications on the server are functioning as expected.
- Monitoring: Monitor web server logs for any attempts to access the removed Skull-Splitter Guestbook files.
# Post-fix command and expected output
ls -l /path/to/skullsplitter/*
No such file or directory
6. Preventive Measures and Monitoring
Regular security assessments can help identify vulnerable software like Skull-Splitter Guestbook.
- Baselines: Update your server baseline to include a check for known vulnerable applications.
- Pipelines: Implement Static Application Security Testing (SAST) tools in your CI/CD pipeline to detect potential vulnerabilities in custom code.
- Asset and patch process: Maintain an inventory of all software installed on your servers, and review security advisories regularly.
7. Risks, Side Effects, and Roll Back
- Risk or side effect 1: Loss of existing guestbook data if not backed up properly. Mitigation is to restore from the pre-change backup.
- Roll back: Restore the Skull-Splitter Guestbook files and data directory from your backup, then restart the web server service.
8. References and Resources
- Vendor advisory or bulletin: No official vendor advisory available for this software.
- NVD or CVE entry: CVE-2005-1620
- Product or platform documentation relevant to the fix: No specific documentation available, as the solution is removal of the software.