What does "malvertising" refer to?

Malvertising refers specifically to online advertisements that are engineered to deliver malware to users' devices. This process often involves the insertion of malicious code within legitimate ad networks, which then get displayed on various web pages. When users click on these ads or even visit the pages hosting them, their systems may become compromised with harmful software without their consent. This method is particularly effective for cybercriminals because it exploits the trust users have in well-known platforms and websites where the ads are displayed, thereby maximizing the chances of infection.

The other concepts presented in the answer choices do not accurately encapsulate the meaning of malvertising. Options related to legitimate marketing strategies or free advertising services miss the core idea of malware distribution inherent to malvertising. In contrast, the focus of malvertising lies solely in its deceptive use of online advertisements for malicious purposes, hence making it a significant threat to users’ cybersecurity.