FREAK!

As you probably read somewhere else, and on another place, and another... on March 3rd 2015, another attack on SSL/TLS was published. Following the tradition of BEAST, CRIME, Heartbleed, LUCKY13 and POODLE this one also has a catchy name: FREAK (Factoring RSA Export Keys).

It's a man-in-the-middle attack where a man in the middle can decrypt a SSL/TLS connection between a client and a server.

Vulnerable *servers* are servers that accept export-grade ciphers (RSA-EXPORT). Checking whether a server is vulnerable can be done in many ways.

• Take for example analyze_hosts.py, a Python wrapper around several tools:

analyze_hosts --ssl HOST

If you see any EXPort ciphers, the server is vulnerable.

• Another way is by using cipherscan

cipherscan HOST:443

If you see any EXPort ciphers, the server is vulnerable.

• Yet another way is by using nmap:

nmap --script ssl-enum-ciphers -p433 HOST

If you see any EXPort ciphers, the server is vulnerable.

You get the idea...

Mitigate this vulnerability server-side by making sure that your server doesn't allow export ciphers in the OpenSSL configuration: add the following expression

!EXP

There are also vulnerable clients...

Clients using OpenSSL are not vulnerable if they were built after CVE-2015-0204 was published.

The current/latest version of 1.0.2-chacha, the OpenSSL fork including ChaCha20 and Poly1305 is not vulnerable. The fork is being kept up to date on a regular base. See https://www.onwebsecurity.com/cryptography/openssl for the latest Windows binaries, and more information on the source.

To paraphrase cryptographer Matthew Green: "Encryption backdoors will always turn around and bite you in the ass. They are never worth it."