UPDATE 6/3: In a statement, Asus confirms the breach affects RT-AX55 or AC3100/AC3200 routers, but says "these vulnerabilities can be fixed." It recommends that those with an affected Asus router (see ...
TL;DR: GreyNoise uncovered the AyySSHush botnet infecting over 8,000 hosts, mainly ASUS routers, exploiting known bypass bugs to gain persistent SSH backdoor access that survives firmware updates.