Alexey's vigilante spree may be illegal, but he is definitely not the first.
In 2014, a hacker accessed thousands of ASUS routers and planted text warnings inside computers with shared folders and hard drives that were located behind those routers, warning users to patch their ASUS device.
In late 2015, a team of vigilante hackers going by the name of the White Team launched the Linux.Wifatch malware that closed security holes on a variety of Linux-based routers. At one point, the White Team's botnet became so big it battledwith the botnet of the infamous Lizard Squad team for the title of the Internet's largest botnet.
In 2017, a more devious vigilante hacker named The Janit0r deployed the BrickerBot malware that erased firmware or bricked IoT devices that had not been updated.
Also in 2017, a hacker made over 150,000 printersspew out a message to their owners to raise everyone's awareness about the danger of leaving printers exposed online.
In 2018, another vigilante renamed tens of thousands of MikroTik and Ubiquiti routers to "HACKED" and other messages to get owners' attention to update their devices.