"This server is vulnerable to a CRIME attack. Make sure you have TLSv1.2 protocol enabled on your server and disable SSL/TLS compression."
The Transport Layer Security (TLS) protocol contains a feature (TLS compression) that allows you to compress the data passed between the server and the browser. You use this feature to reduce the bandwidth and the latency issues associated with encrypting and decrypting large amounts of data. TLS compression is added to the Client Hello message. Including TLS compression is optional.
In a Compression Ratio Info-leak Made Easy attack, the attacker recovers the content of secret authentication cookies and uses this information to hijack an authenticated web session. The attacker uses a combination of plaintext injection and TLS compression data leakage to exploit the vulnerability. The attacker lures the browser to make several connections to the website. The attacker than compares the size of the ciphertexts sent by the browser during each exchange to determine parts of the encrypted communication and hijack the session.
DigiCert is the world’s premier provider of high—assurance digital certificates—providing trusted SSL, private and managed PKI deployments, and device certificates for the emerging IoT market. Since our founding almost fifteen years ago, we’ve been driven by the idea of finding a better way. A better way to provide authentication on the internet. A better way to tailor solutions to our customer’s needs. Now, we’ve added Symantec’s experience and talent to our legacy of innovation to find a better way to lead the industry forward, and build greater trust in identity and digital interactions.
©2019 DigiCert, Inc. All rights reserved. DigiCert and its logo are registered trademarks of DigiCert, Inc. Symantec and Norton and their logos are trademarks used under license from Symantec Corporation. Other names may be trademarks of their respective owners.