Introduction to TLS protocols #

TLS is a cryptographic protocol used to secure data transmission over the internet. There have been several versions of TLS over the years, each introducing improvements in security and performance. Here’s a brief explanation of some of the main TLS versions:

TLS 1.0: Released in 1999, TLS 1.0 was the first version of TLS. It provided a way to encrypt data between a client (e.g., a web browser) and a server, ensuring confidentiality and integrity. However, it is now considered outdated and vulnerable to various attacks.

TLS 1.1: Introduced in 2006, TLS 1.1 addressed some vulnerabilities in TLS 1.0. It improved security by removing weaker cryptographic algorithms and providing protection against certain types of attacks. However, it is also considered outdated and has been largely replaced by newer versions.

TLS 1.2: Released in 2008, TLS 1.2 brought significant security enhancements. It introduced more robust encryption algorithms and improved resistance against various attacks. TLS 1.2 is widely used and considered secure for most applications.

TLS 1.3: Introduced in 2018, TLS 1.3 is the latest version of TLS. It offers improved security and performance compared to TLS 1.2. TLS 1.3 minimizes handshake latency, enhances forward secrecy, and removes older, less secure features. It is now the recommended version for securing internet communications.

TLS versions are crucial for ensuring secure and encrypted communication on the internet. It’s essential for organizations and individuals to stay up-to-date with the latest TLS versions to maintain the highest level of security in their online interactions.

Why to check the TLS protocols used in your servers #

Checking TLS (Transport Layer Security) protocols on a server is paramount for data security and regulatory compliance. TLS protocols, which encrypt data during transmission, help safeguard sensitive information from potential eavesdropping and unauthorized access. Regularly verifying and updating TLS versions on a server is crucial to stay ahead of security vulnerabilities, as older versions may have known weaknesses that can be exploited by attackers. Compliance with data protection regulations is often contingent on using secure TLS protocols, and failure to do so can result in legal consequences and financial penalties.

Furthermore, keeping TLS protocols up-to-date ensures compatibility with a diverse range of client devices and browsers, preventing connectivity issues and ensuring a smooth user experience. It also demonstrates a commitment to security and builds trust with users, which is especially vital for services handling sensitive data such as e-commerce and online banking. Overall, checking and maintaining TLS protocols on a server is a fundamental element of robust cybersecurity and responsible server management, protecting both data and the reputation of the service provider.

How to test TLS protocols #

Nmap, short for “Network Mapper,” is a widely-used open-source network scanning tool designed for discovering and mapping network hosts, services, and open ports within computer networks. Network administrators, security professionals, and ethical hackers rely on Nmap to assess the security of networked systems. It excels at port scanning, service detection, and operating system identification, enabling users to gain detailed insights into a network’s composition and potential vulnerabilities. Nmap also supports scripting for automation, aiding in vulnerability assessment, network inventory, and security auditing. Responsible and authorized use of Nmap is essential, as it plays a vital role in network security and administration but must adhere to ethical and legal guidelines.

Nmap can be used to scan the SSL ports to know which TLS protocols are supported, like it is shown below:

root@noid-ee-01:~/$ nmap --script ssl-enum-ciphers -p 443 relianoid.com
Starting Nmap 7.80 ( https://nmap.org ) at 2023-09-21 20:11 CEST
Nmap scan report for relianoid.com (178.128.175.67)
Host is up (0.047s latency).

PORT    STATE SERVICE
443/tcp open  https
| ssl-enum-ciphers: 
|   TLSv1.0: 
|     ciphers: 
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (ecdh_x25519) - A
|     compressors: 
|       NULL
|     cipher preference: indeterminate
|     cipher preference error: Too few ciphers supported
|   TLSv1.1: 
|     ciphers: 
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (ecdh_x25519) - A
|     compressors: 
|       NULL
|     cipher preference: indeterminate
|     cipher preference error: Too few ciphers supported
|   TLSv1.2: 
|     ciphers: 
|       TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (ecdh_x25519) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 (ecdh_x25519) - A
|       TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA (ecdh_x25519) - A
|     compressors: 
|       NULL
|     cipher preference: server
|_  least strength: A

Nmap done: 1 IP address (1 host up) scanned in 1.90 seconds

In this example, the protocols TLSv1.0, TLSv1.1 and TLSv1.2 are supported with Elliptic Curve ciphers, so it is a very good level of strong SSL.

The “ssl-enum-ciphers” script in Nmap is a tool for evaluating the security of SSL/TLS encryption on a target server. It identifies and lists supported ciphers, assesses their strength and security, provides details about each cipher suite, detects vulnerabilities, and reveals cipher suite preferences. This script is invaluable for security professionals and administrators to assess and enhance the security of SSL/TLS configurations, ensuring that servers use strong and secure cryptographic algorithms while identifying potential vulnerabilities and weak ciphers.