What is a botnet?
A botnet is a network of malware-infected devices controlled by one attacker (a botmaster). The infected machines – bots or zombies – run commands without their owners’ knowledge, enabling DDoS, spam, credential stuffing, and large-scale credential theft. Botnets range from thousands to millions of devices.
What is a botnet attack?
A botnet attack uses a network of malware-infected devices – controlled remotely by a single operator – to execute coordinated malicious activity at scale, from DDoS and spam to credential theft and account takeover. Modern botnets increasingly double as harvesting infrastructure, pulling credentials and session cookies from every machine they compromise.
How botnets fuel identity attacks
DDoS and spam are the classic uses, but the bigger enterprise risk today is the botnet as a credential engine, in two modes:
- Harvesting. Many bots run infostealer modules that pull credentials, cookies, and tokens from each machine. One campaign can generate millions of stealer logs in days, feeding brokers and stuffing operators.
- Distribution. Botnets give credential stuffing its muscle, spreading login attempts across millions of residential IPs to defeat rate limiting and IP-based fraud controls.
Fresh stolen credentials plus distributed infrastructure to test them is what makes botnet-driven attacks so hard to stop with traffic defenses alone.
Botnet-harvested credentials don’t stay put. They’re packaged and resold across criminal markets within days. The 2026 Annual Identity Exposure Report traces how that data moves and how fast →
Why traffic-based defenses fall short
Because botnets distribute requests across millions of rotating IPs, IP rate limiting and source blocking are largely ineffective, and residential proxies make bot traffic look like ordinary home connections. Trying to distinguish botnet logins from legitimate ones at scale is a losing battle.
The more reliable move is to remove the value of the stolen credentials before the botnet ever tests them: monitor criminal markets for exposed employee and customer credentials and force resets upstream. Dark web monitoring that reaches criminal channels before packaged credential sets are widely distributed gives you the earliest possible warning, well before the login traffic arrives.
Botnet vs. distributed denial-of-service (DDoS)
The terms get used interchangeably, but one is the infrastructure and the other is a use of it:
- A botnet is the network of infected devices itself – a standing resource an operator controls.
- A DDoS attack is one thing a botnet can be pointed at; the same botnet may instead harvest credentials or run credential stuffing.
- Why it matters: treating a botnet as only a DDoS problem misses its identity role – the network flooding your perimeter may also hold your users’ stolen credentials.
If your users’ credentials are already in a botnet’s data stream, stuffing attempts are a matter of time.
Check Your Exposure to see what’s tied to your domain.
Frequently Asked
It uses a network of malware-infected devices controlled by one operator to run coordinated activity – DDoS, spam, credential stuffing, and credential theft – at scale. Bots execute commands silently, and many modern botnets harvest credentials and session cookies from every machine they infect.
Two ways. They harvest credentials and cookies via infostealer modules, packaging them as stealer logs sold for account takeover and ransomware. And they execute credential stuffing directly, using distributed IPs to test millions of stolen pairs against login portals while evading detection.
IP-based controls are weak against distributed botnets, so the most effective approach is upstream: monitor criminal markets for exposed credentials and force resets before they can be tested. Detecting the exposure beats trying to filter the traffic.