What Is the FREAK Vulnerability? How to Prevent SSL FREAK Attacks

The Factoring RSA Export Keys (FREAK) vulnerability, also known as CVE-2015-0204, is a major SSL/TLS security problem for servers and clients that support outdated protocols and ciphers. In a nutshell, the FREAK Attack enables attackers to force systems to use vulnerable “export cipher suites” and small key pairs. This allows them to intercept and decrypt (what should have been) secure communications.

This article offers insights into the FREAK vulnerability, shows an example of a hacked vulnerable server, and explains how you can identify and mitigate the FREAK vulnerability exploit to protect your web servers. In particular, we look at how CertPanel SSL Monitor can help spot and fix this issue.

TL;DR: Key Facts About the FREAK Attack

Common Vulnerability and Exposures (CVE) ID: CVE-2015-0204
What the FREAK Attack Does: Allows attackers to intercept and decrypt HTTPS traffic by forcing servers and clients to use intentionally insecure “export-grade” cryptography.
How It Works: In this downgrade attack, threat actors exploit a vulnerability that forces SSL/TLS connections to use weak cipher suites and 40- or 56-bit cryptographic keys.
Affected Systems: Primarily affects servers and clients using vulnerable SSL/TLS configurations, particularly those that support export-grade RSA keys.

The CVE-2015-0204 Exploit (FREAK Vulnerability) Explained

Although it’s not new, the FREAK Attack still poses a major threat to vulnerable legacy systems and clients. (Reason #892,000 for why you should not rely on old, unsupported systems.) This vulnerability, which was discovered in 2015, triggers the use of insecure cipher suites from the 90s. This cryptographic downgrade attack puts clients and servers that support these RSA export-grade keys at risk of compromise or exposure.

So, why are these cipher suites and keys so weak? They were designed that way to adhere to regulations surrounding the export of cryptographic technologies to foreign entities. These keys were made intentionally weak to enable U.S. security and intelligence organizations to decrypt and read confidential data. Unfortunately, bad guys know this and can exploit vulnerabilities to trick a server and client into using them. This lets them read secret messages between the server and client.

How to Detect the FREAK Vulnerability Using Manual or Automated Methods

You can manually check to see which ciphers or cipher suites your server supports using several tools. For our example, we’ll use OpenSSL.

Manually Check Your Domain’s Supported Cipher Suites in OpenSSL

Enter the following OpenSSL directives. (Note: Be sure to replace the generic values with your unique domain and the specific cipher suits you want to check.)

openssl s_client -connect <hostname>:<port> -cipher <ciphersuite-name>

For example, if we want to check to see whether the export cipher suits “EXP-DES-CBC-SHA” is supported on our test server, we can use this command:

openssl s_client -connect travel.itsatest.site:443 -cipher EXP-DES-CBC-SHA

Wondering why we used -cipher instead of -ciphersuites? It’s because –cipher works for TLS 1.2 and earlier cipher suites, whereas -ciphersuites only works with TLS 1.3 cipher suites, which follow a different format/naming convention.

Here’s a quick look at what you’re likely to see:

FREAK attack graphic: A snippet from OpenSSL showing that a specified export cipher suite isn't suppoted on a test site

Don’t have time to run every relevant cipher suite? Then you’re in for some good news, as there’s another way…

Automatically Scan for the FREAK Vulnerability Exploit Using SSL Monitor

Using CertPanel’s SSL Monitor, you can scan your server to identify if it’s susceptible to the FREAK Attack (and 110+ other vulnerabilities). SSL Monitor quickly identifies weak protocol configurations, misconfigurations, and weak cryptography (including support for export-grade cipher suites and RSA keys).

Get SSL Monitor

Here’s how you can check your domain for vulnerable cipher suites that bad guys can use to launch a FREAK Attack.

Access SSL Monitor: Go to CertPanel and activate the SSL Monitor feature.

Freak Attack Vulnerability Exploit graphic: This screenshot shows where to activate SSL Monitor in the CertPanel dashboard.

Enter your domain or IP address: Input the domain name or IP address of the server you want to scan for vulnerabilities.

A screenshot showing how to set up SSL Monitor to scan your hostname domain or IP address

Start the scan: Click Go to SSL Monitor to initiate a scan of your domain or IP address. This process analyzes your SSL/TLS configuration and reports any weaknesses.

A screenshot showing what you'll see when an initial domain scan is in progress using CertPanel's SSL Monitor feature. This scan enables you to find and identify 110+ vulnerabilities, including those associaed with the FREAK attack

Review your individual report: Check the results for any mentions of weak or export-grade RSA keys and implement the remediation steps.

An example of the SSL Vulnerability info in CertPanel's SSL Monitor that displays for the FREAK Attack vulnerability exploit

How to Mitigate the FREAK Vulnerability to Prevent Exploitation Attacks

For starters, ensure your server and OpenSSL client are up to date. If not, update or patch them now so bad guys can’t exploit these outdated, vulnerable systems.

If you haven’t already done so, ensure your server is set to support TLS 1.2 as the minimum security protocol. (Ideally, TLS 1.3.)

Disable Export Ciphers in Apache and NGINX

To secure your server against FREAK, you need to disable support for export-grade RSA keys and ensure your server is configured to use strong encryption standards. Below are the steps to remove export ciphers for both Apache and NGINX Linux configurations:

Step 1: Open the Relevant Configuration File on Your Server

Apache users: You’ll find this file at /etc/httpd/conf.d/ssl.conf or /etc/apache2/sites-enabled/default-ssl.conf.

NGINX users: You can locate this config file at /etc/nginx/nginx.conf or in the sites-available folder.

Step 2: Change the Cipher Suite Settings to Remove Weak Ciphers

Apache users: Locate the SSLCipherSuite directive and modify or update it to:

SSLCipherSuite HIGH:!aNULL:!MD5:!EXPORT

A screenshot showing how to remove export cipher suites and other insecure cipher suites in Apache

NGINX users: Modify or update the ssl_ciphers directive to say the following:

ssl_ciphers HIGH:!aNULL:!MD5:!EXPORT;

An example showing how to remove export cipher suites and other insecure ciphers in NGINX

Step 3: Save the Changes and Restart Your Web Server to Update the New Settings

For Apache:

sudo service apache2 restart

For NGINX:

sudo service nginx restart

Step 4: Re-Run the Server Vulnerability Scanner

Check whether your changes have resolved the FREAK vulnerability.

A screenshot of CertPanel's SSL Monitor scan results, which shows that the FREAK vulnerability that's tied to FREAK downgrade attacks has been mitigated

Final Takeaways

The FREAK vulnerability exploit has a significant impact on SSL/TLS security for vulnerable servers and clients, making encrypted communications less secure. Tools like CertPanel SSL Monitor help organizations spot these issues and act quickly to protect their servers. Follow the outlined mitigation steps for your specific server to ensure your environment is protected against FREAK Attacks.