spyware
US /ˈspaɪ.wer/
UK /ˈspaɪ.wer/

1.
software that enables a user to obtain covert information about another's computer activities by transmitting data covertly from their hard drive.
:
•
Always install antivirus software to protect against spyware.
•
The company's network was compromised by a sophisticated spyware attack.