A lent his laptop to B. When in possession of the laptop, B inserted a pen drive into the laptop. When he did a virus scan, he realized that the pen drove was infected. Since he urgently required a file that was on the laptop, he nvertheless opened the files on the pen drive, in the process infecting the laptop.
Criminal mischief is defined under Section 425 of IPC. Mischief is committed when a person with intent to cause, or knowing that he is likely to cause, wrongful loss or damage to the public or to any person, causes the destruction of any property, or any such change in any property or in the situation thereof as destroys or diminishes its value or utility, or affects it injuriously.