First, a page on classmates was hacked, then in my world, where to dig in order to understand the problem?

Question

Malware

Hello.
The computer was in the hands of an attacker, Windows 7 was installed, then classmates were hacked and messages were sent out.
Then they upgraded to Windows 10, mail.ru mail was hacked and messages were sent out again.
What actions can help prevent such situations?

Answer 1

Perhaps you have the same passwords on all resources.
Change passwords, do not let the computer fall into the wrong hands, if it has already fallen, then delete the system, because bookmarks could remain in it, for example, a keyboard interceptor that remembers everything you type on the keyboard and sends it to the owner.

Answer 2

Change passwords, check startup, if there is nothing there, then constantly monitor the task manager to identify unnecessary programs. You can also check the settings almost and so on. for password recovery - attackers could put their recovery addresses there.

Answer 3

Reinstall the system.