What is JA3?
JA3 is a method to fingerprint a SSL/TLS client connection based on fields in the Client Hello message from the SSL/TLS handshake. Because the SSL/TLS handshake is sent in clear text we can use it to fingerprint any client application using the information within the Client Hello message.
What is JA3 digest?
JA3 is a method to profile the way server and clients do their SSL/ TLS handshake. It has been created by Salesforce engineers, John B. Althouse, Jeff Atkinson and Josh Atkins.
What is TLS fingerprint?
TLS Fingerprinting is a method, developed to assist network monitoring. This paper takes a closer look on how TLS Fingerprinting works and analyzes the advantages of it as a client identification method by reviewing different Fingerprinting implementations. Index Terms—Transport Layer Security, Secure Socket.
What is TLS hash?
The key in the encryption used by SSL and TLS is based a value created by a hash: a number that has been passed through an equation. This is secure so long as the hash algorithm is secure.
Can a JA3 still be unique to a client?
Therefore the JA3 will still be unique per client. After creating JA3 we started playing with using the same method to fingerprint the server side of the TLS handshake, the TLS Server Hello message.
How are JA3 and ja3s used for fingerprinting?
JA3 and JA3S are TLS fingerprinting methods. JA3 fingerprints the way that a client application communicates over TLS and JA3S fingerprints the server response. Combined, they essentially create a fingerprint of the cryptographic negotiation between client and server.
What can a JA3 hash be used for?
For example, a JA3 hash could be used to identify that Internet Explorer was the application establishing an encrypted connection, but there would be no way to determine if the traffic was a user surfing the internet or malware using Internet Explorer for Command and Control (C2).
When to use JA3 for threat hunting and incident response?
It is important to take collisions into account when performing investigations based on JA3 (please note I am not talking on hash collisions here). Still, JA3 can be very powerful when used for Threat Hunting and Incident Response. Why hunt for PowerShell?