“An infamous black hat hacker and internet troll has admitted to hijacking 29,000 printers in dozens of college campuses across the US to remotely print out multiple copies of racist and anti-Semitic flyers between Thursday to Friday 24-25 March. Andrew Auernheimer, known as Hacker Weev, explained in a blog post how he was able to exploit a vulnerability in certain online printers.
Auernheimer used a single line of Bash script code to scan the internet for unprotected printers that were connected to the web using the open port 9100, and then created a PostScript file containing a flyer advertising a white supremacist news website called Daily Stormer. Since the printers were programmed to automatically print this file format out, they immediately complied.”
Source: Hacker Weev hijacked 29,000 printers to spew anti-Semitic flyers across US colleges