Researchers have found a way to run malicious code on systems with Intel processors in such a way that the malware can’t be analyzed or identified by antivirus software, using the processor’s own features to protect the bad code. As well as making malware in general harder to examine, bad actors could use this protection to, for example, write ransomware applications that never disclose their encryption keys in readable memory, making it substantially harder to recover from attacks.

https://arstechnica.com/gadgets/2019/02/researchers-use-intel-sgx-to-put-malware-beyond-the-reach-of-antivirus-software/