Check openssl version mac#

This ciphersuite is not compiled by default in OpenSSL 3.0, and is not available within the default provider or the default ciphersuite list. In order for this attack to work both endpoints must legitimately negotiate the RC4-MD5 ciphersuite. an attacker cannot decrypt data that has been encrypted using this ciphersuite - they can only modify it. The confidentiality of data is not impacted by this issue, i.e. Note that in the absence of an attacker this bug means that an OpenSSL 3.0 endpoint communicating with a non-OpenSSL 3.0 endpoint will fail to complete the handshake when using this ciphersuite. In this case both clients and servers could be affected, regardless of the application protocol. If both endpoints are OpenSSL 3.0 then the attacker could modify data being sent in both directions. Therefore, in such a case, only an OpenSSL 3.0 server would be impacted when talking to a non-OpenSSL 3.0 client. Many application protocols require data to be sent from the client to the server first.

Note that data sent from an OpenSSL 3.0 endpoint to a non-OpenSSL 3.0 endpoint will always be rejected by the recipient and the connection will fail at that point.

Check openssl version mac#

An attacker could exploit this issue by performing a man-in-the-middle attack to modify data being sent from one endpoint to an OpenSSL 3.0 recipient such that the modified data would still pass the MAC integrity check. This makes the MAC key trivially predictable. The OpenSSL 3.0 implementation of the RC4-MD5 ciphersuite incorrectly uses the AAD data as the MAC key.