Botnets are typically used by attackers for a variety of malicious activities, most commonly for:

Generating and distributing spam messages: Botnets can send out large volumes of spam emails to promote products or services, or to distribute malware.

Conducting DDoS attacks: Distributed Denial of Service (DDoS) attacks are often carried out using botnets to overwhelm a target's servers with traffic.

Scanning for system & application vulnerabilities: Botnets can be used to scan a large number of systems for vulnerabilities that can be exploited in further attacks.

However,vishing attacks, which involve voice phishing through phone calls, are not commonly associated with the use of botnets.Vishing typically involves direct voice communication to trick individuals into divulging sensitive information and does not leverage the distributed computing power of botnets, which is central to their usual applications such as spam distribution, DDoS attacks, and vulnerability scanning123.