1. Introduction
The ht://dig htsearch sort Parameter XSS vulnerability affects the remote web server’s CGI script, specifically htsearch. This is a cross-site scripting (XSS) flaw that allows attackers to inject malicious code into webpages viewed by users of the affected site. Systems running vulnerable versions of ht://Dig are at risk. Successful exploitation could lead to compromise of user accounts and data theft. Confidentiality, integrity, and availability may be impacted.
2. Technical Explanation
The vulnerability occurs because the htsearch CGI script does not properly sanitize input provided through the ‘sort’ parameter. This allows an attacker to inject arbitrary HTML or JavaScript code into a webpage. An unauthenticated remote attacker can exploit this flaw by crafting a malicious URL containing the injected code, which is then executed in the browser of any user who visits that URL. The vulnerability is tracked as CVE-2007-6110 and has a CWE score of 79 (Improper Neutralization of Input During Web Page Generation (‘Cross-site Scripting’)).
- Root cause: Missing input validation on the ‘sort’ parameter within the htsearch CGI script.
- Exploit mechanism: An attacker crafts a URL with malicious JavaScript code in the ‘sort’ parameter, which is then reflected back to the user’s browser and executed. For example:
http://example.com/htsearch?sort= - Scope: Affected versions of ht://Dig containing the vulnerable htsearch CGI script are in scope.
3. Detection and Assessment
To confirm vulnerability, check the version of ht://Dig installed on your system. A thorough assessment involves attempting to inject a simple XSS payload through the ‘sort’ parameter.
- Quick checks: Check if the htsearch CGI script is accessible via a web browser.
- Scanning: Nessus vulnerability ID 34899 may detect this issue, but results should be verified manually.
- Logs and evidence: Examine web server logs for requests containing suspicious characters or JavaScript code in the ‘sort’ parameter of htsearch CGI script access attempts.
# Example command to check if htsearch is accessible (replace example.com with your domain)
curl -I http://example.com/htsearch
4. Solution / Remediation Steps
Currently, there is no known solution available for this vulnerability. Mitigation strategies should be implemented to reduce risk until a patch becomes available.
4.1 Preparation
- Ensure you have access to modify the htsearch CGI script or its configuration. A rollback plan involves restoring the original web server configuration.
- A change window may be required depending on your organization’s policies, and approval from security teams might be necessary.
4.2 Implementation
- Step 1: If possible, disable access to the htsearch CGI script if it is not actively used.
- Step 2: Implement a web application firewall (WAF) rule to block requests containing potentially malicious code in the ‘sort’ parameter.
- Step 3: Monitor web server logs for any attempts to exploit this vulnerability.
4.3 Config or Code Example
Before
# htsearch CGI script without input validation (example)
$sort = $QUERY_STRING;
print "You sorted by: $sort";
After
# htsearch CGI script with basic input sanitization (example - this is a simplified example and may not be sufficient for all cases)
$sort = htmlspecialchars($QUERY_STRING, ENT_QUOTES, 'UTF-8');
print "You sorted by: $sort";
4.4 Security Practices Relevant to This Vulnerability
Several security practices can help prevent this type of vulnerability. Input validation is crucial for blocking malicious code. Least privilege limits the impact if an attacker gains control. Safe defaults reduce the attack surface. Regular patch cadence ensures timely fixes are applied.
- Practice 1: Implement strict input validation on all user-supplied data to block potentially harmful characters and scripts.
- Practice 2: Apply the principle of least privilege by granting only necessary permissions to web server processes and users.
4.5 Automation (Optional)
No automation script is provided due to the lack of a specific patch. WAF rules can be automated using tools like ModSecurity or cloud provider-specific firewalls.
5. Verification / Validation
- Post-fix check: Access the htsearch CGI script through a web browser. Verify that any input provided in the ‘sort’ parameter is properly encoded or blocked.
- Re-test: Attempt to inject the same XSS payload used during detection and confirm it does not execute.
- Monitoring: Monitor web server logs for any attempts to exploit this vulnerability, looking for blocked requests or suspicious activity related to the htsearch CGI script.
# Example command to check if XSS payload is blocked (replace example.com with your domain)
curl -I http://example.com/htsearch?sort=
6. Preventive Measures and Monitoring
Update security baselines to include input validation requirements for all web applications. Incorporate static application security testing (SAST) into CI/CD pipelines to identify vulnerabilities early in the development process. Implement a regular patch or configuration review cycle to address known vulnerabilities promptly.
- Baselines: Update your web server security baseline to require strict input validation and output encoding for all user-supplied data.
- Asset and patch process: Establish a regular schedule for reviewing and applying security patches to web server software and components.
7. Risks, Side Effects, and Roll Back
Disabling the htsearch CGI script may impact functionality if it is actively used. Implementing WAF rules could potentially block legitimate traffic if not configured carefully. The roll back plan involves restoring the original web server configuration or removing the WAF rule.
- Risk or side effect 1: Disabling htsearch may break existing features that rely on it.
- Risk or side effect 2: Overly aggressive WAF rules could block legitimate user requests.
- Roll back: Restore the original web server configuration from backup, or remove any newly implemented WAF rules.
8. References and Resources
Links to resources related to this specific vulnerability.
- Vendor advisory or bulletin: http://www.nessus.org/u?a7899e11
- NVD or CVE entry: CVE-2007-6110
- Product or platform documentation relevant to the fix: No specific documentation available at this time.