CVE-2022-1434

The OpenSSL 3.0 implementation of the RC4-MD5 ciphersuite incorrectly uses
the AAD data as the MAC key. This makes the MAC key trivially predictable.
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. 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. Many application protocols require data to be sent
from the client to the server first. Therefore, in such a case, only an
OpenSSL 3.0 server would be impacted when talking to a non-OpenSSL 3.0
client. If both endpoints are OpenSSL 3.0 then the attacker could modify
data being sent in both directions. In this case both clients and servers
could be affected, regardless of the application protocol. 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. The confidentiality of data is not
impacted by this issue, i.e. an attacker cannot decrypt data that has been
encrypted using this ciphersuite - they can only modify it. In order for
this attack to work both endpoints must legitimately negotiate the RC4-MD5
ciphersuite. This ciphersuite is not compiled by default in OpenSSL 3.0,
and is not available within the default provider or the default ciphersuite
list. This ciphersuite will never be used if TLSv1.3 has been negotiated.
In order for an OpenSSL 3.0 endpoint to use this ciphersuite the following
must have occurred: 1) OpenSSL must have been compiled with the
(non-default) compile time option enable-weak-ssl-ciphers 2) OpenSSL must
have had the legacy provider explicitly loaded (either through application
code or via configuration) 3) The ciphersuite must have been explicitly
added to the ciphersuite list 4) The libssl security level must have been
set to 0 (default is 1) 5) A version of SSL/TLS below TLSv1.3 must have
been negotiated 6) Both endpoints must negotiate the RC4-MD5 ciphersuite in
preference to any others that both endpoints have in common Fixed in
OpenSSL 3.0.3 (Affected 3.0.0,3.0.1,3.0.2).

Notes