TLS LOGJAM Vulnerability Scanner

TLS LOGJAM Vulnerability Scanner: Core Features and Principles

Is your website's TLS encryption at risk of man-in-the-middle (MitM) attacks due to outdated, weak Diffie-Hellman parameter groups? This tool scans the TLS handshake process of a specified domain to inspect its key exchange algorithm configuration and determine if the LOGJAM vulnerability exists. The LOGJAM vulnerability is a TLS protocol flaw that allows attackers to downgrade connections to use easily crackable 512-bit Diffie-Hellman groups, potentially decrypting HTTPS traffic. Our tool's output clearly indicates whether the target domain is at risk on a specific port (usually 443) and provides a security rating along with the relevant CVE identifier.

Why Choose Our TLS LOGJAM Vulnerability Scanner?

• Laser-Focused on Core Vulnerabilities: Specifically targets LOGJAM, a distinct and dangerous TLS MitM attack vector, delivering clear and definitive results.
• Professional Security Identifiers: Outputs standardized CVE (e.g., CVE-2015-4000) and CWE identifiers, helping security professionals quickly locate vulnerability details and remediation plans.
• Simple and Direct Operation: Just enter the domain name and port (defaults to 443) to instantly generate a scan report—no complex configurations or specialized knowledge required.

How to Use This Tool

1. Enter the target website domain you want to scan in the "Domain" input field, e.g., example.com.
2. (Optional) Specify the TLS port in the "Port" input field; this is typically 443.
3. Click the scan button and wait for the tool to complete the analysis of the target server's TLS configuration.
4. Review the generated scan report below, paying special attention to the "Security" status and "Description" fields.

Frequently Asked Questions (FAQ)

Q: What exactly is the LOGJAM vulnerability, and how do I fix it?

A: The LOGJAM vulnerability (CVE-2015-4000) is an attack against the Diffie-Hellman key exchange in the TLS protocol. To fix it, you need to disable all export-grade cipher suites on your server and upgrade your Diffie-Hellman parameter groups to at least 2048-bit.

Q: Does an "OK" result mean my server is completely secure?

A: Not entirely. An "OK" result only means the LOGJAM vulnerability was not detected. Your website might still have other TLS configuration issues (such as weak cipher suites or certificate errors). We recommend conducting a comprehensive TLS security audit.

Important Notes

Please only scan domains for which you have administrative privileges or explicit authorization; unauthorized scanning may violate laws and regulations. The scan results are point-in-time; you must rescan if server configurations change. This tool primarily targets the standard HTTPS port (443). Non-standard ports or complex network environments (such as behind a CDN or WAF) may affect scan accuracy. The scanning process initiates a TLS connection to the target server; ensure your actions comply with the target site's terms of service.

Technical Notes & Best Practices

For security and DevOps professionals, we recommend integrating this tool into your regular TLS configuration audit workflow. A typical input/output example: entering vulnerable.example.com with port 443 might output a "Vulnerable" security status linked to CVE-2015-4000. Note that the LOGJAM vulnerability typically affects servers that still support DHE_EXPORT suites or use common, low-bit DH parameters. Beyond detection, taking remediation action is crucial: in web server configurations like Nginx or Apache, disable all cipher suites containing "EXPORT" or "DHE" with insufficient key lengths, and generate a unique, strong Diffie-Hellman parameter file. For modern servers, using ECDHE key exchange is highly recommended, as it offers superior efficiency and security compared to traditional DHE.