Certified Ethical Hacker (CEH) Practice Question

Mirai's authors embedded a short list of factory-default username and password pairs for dozens of popular IP cameras, DVRs, and SOHO routers. The malware scanned the public IPv4 space for systems with Telnet open (ports 23/2323), attempted those credentials automatically, and, upon success, downloaded its binary to enlist the device. Because many owners never changed these hard-coded logins, the success rate was extremely high, letting Mirai swell quickly enough to generate the multi-Tbps attack that crippled Dyn. No zero-day vulnerabilities, DNSSEC tricks, BGP hijacking, or high-amplification reflectors were required-just the widespread prevalence of unchanged default credentials on Internet-exposed IoT gear.