10 percent of attacks directed to Telnet are directed to port 23, Telnet uses. This marks a peak which is unusual for the aging protocol. Port 445, which is commonly used as a gateway for Microsoft products, was the most targeted. Port 23 is “overwhelming top slot for targeted attacks” in Egypt, Peru and Turkey, Akamai says. In China, however, attacks on SSH were more common than port 445, report says. Report: Port 445 attacks have been responsible for much of the traffic attack in Brazil, Germany, Italy, Russia, Taiwan.
Source: https://thehackernews.com/2011/01/hackers-turn-back-time-attack-telnet.html