I'm sure there are instances of this, but I ask it because malwares are often so makeshift that I could definitely see their authors purposely using weaker forms of authentication to perform communications (or no authentication at all) just for the sake of time or efficiency. I'm wondering what the general trend is in using strong authentication protocols for C2 and if breaking those protocols could be an avenue for disabling malwares.
In 2017, security researchers at Cyren discovered that over 1/3 of malware was using HTTPS for their C2 activities.
"Breaking those protocols" is never the answer, it is equivalent to when Kazakhstan forced a MITM attack on the entire country.
This could depend on per author / group behind the malware,
With the widespread adoption of Lets Encrypt and the lower barrier of entries for things such as SSL certs I would speculate that it will become more common.
It could potentially mitigate some IPS / IDS systems from viewing the traffic that is being sent