You may not know it, but viruses and other malware could be stealing data and destroying your systems. / Credit: Malware attack image via Shutterstock. Malware could be lurking in your computer — and you might not even know it. Viruses, spyware, ransomware and other malware attacks have become so sophisticated that they could be wreaking havoc on your systems without showing any signs — that is, until it's too late.