Cryptographic Downgrade Attempts

Danny Y@zendannyy

•updated Feb 18, 2026•3•0•112

This rule detects attempts to use outdated or weak cryptographic algorithms and protocols by monitoring command-line arguments of common network and cryptographic utilities. Specifically, it looks for the use of RC4, DES, 3DES, RSA1024, MD5 ciphers, or TLS 1.0, TLS 1.1, and SSL 3.0 protocols, as well as the '--insecure' flag, when executed by applications like openssl, gpg, ssh, or curl. This could indicate an adversary attempting to downgrade cryptographic protections to facilitate eavesdropping or other attacks.