What are botnets? How they can affect your Mac and network

Botnets let attackers control many infected devices at once. They can be used to send spam, launch DDoS attacks, spread malware, test stolen passwords, relay traffic, or collect information from infected systems. The owner may not notice anything obvious, especially if the malware runs quietly in the background and only uses small amounts of system resources at a time.

A device can become part of a botnet if malware is installed or attackers gain access through weak passwords, outdated software, unsafe downloads, or exposed settings. On a Mac, this may happen through malicious apps or browser extensions, unsafe files, or older software. Routers and smart devices are often targeted through default passwords or outdated firmware.

Yes. Macs are not the most common botnet targets compared with poorly secured routers and IoT devices, but they can still be infected by botnet malware. Past Mac threats such as Flashback showed that Macs can become part of larger botnet operations when malware gets installed or a vulnerability is exploited. Keeping macOS updated and using trusted antivirus protection helps reduce the risk.

A botnet is the network of infected devices, while the software that turns a device into a bot is usually malware. People often use the terms together because botnet malware is what gives attackers remote control over infected devices. A botnet is not a single virus, but it usually depends on malware or compromised device access to work.

Possible signs of a botnet infection include a slower Mac, unusual overheating, heavy data use, battery drain, strange network activity, suspicious startup items, browser changes, or alerts from security software, your router, or your internet provider. These signs do not always mean botnet malware is present, but they are worth checking if they appear suddenly or continue after a restart.

Start by disconnecting the affected device from the internet if you suspect active malware. On a Mac, run a trusted malware scan, remove suspicious apps or files, update macOS and your browser, and change important passwords from a clean device. For routers and smart devices, update firmware, change default passwords, and consider a factory reset if the device still behaves unusually.