If you manage servers, IoT devices, or basically anything with a network interface, botnets are a threat you can't ignore and unlike a lot of attacks, they're built specifically to not look like an attack at all.
Here's the practical rundown.
What a botnet actually is
A botnet = a collection of compromised devices (bots, or "zombies") under an attacker's remote control. That's it. The devices could be a personal laptop, a VPS, an office router, a security camera keep functioning normally for their legitimate owner while quietly executing commands from a C2 (command-and-control) server in the background.
The unsettling part for anyone in ops: infected devices often show zero visible symptoms. No crash, no obvious log entry screaming "I'm compromised." That's why detection has to be proactive, not reactive.
Modern botnets have also gotten a lot more resilient to takedown. Microsoft's research into the Kazuar botnet (May 2026) documented a modular, peer-to-peer architecture with multiple C2 channels meaning killing one C2 server doesn't kill the botnet. Bots can talk to each other directly.
Attack types you'll actually see
| Type | What it does |
|---|---|
| DDoS | Floods a target with distributed traffic until it goes down |
| Data theft | Harvests credentials, cookies, browser data at scale |
| Spam/malware distribution | Uses compromised hosts to send spam or push phishing payloads |
| Crypto mining | Hijacks CPU/GPU cycles; shows up as unexplained load and power draw |
| IoT compromise | Targets routers/cameras/smart devices usually the weakest security posture on the network |
Detection signals worth instrumenting
No single signal is conclusive you need correlated evidence across layers. The three worth building alerts around:
1. Network behavior anomalies
Watch for a device suddenly reaching out to domains/IPs outside its normal baseline especially with periodic, beacon-like timing (classic C2 check-in pattern).
2. Resource usage drift
CPU, memory, or bandwidth spikes with no corresponding legitimate workload. On its own this is noisy (plenty of false positives), but combined with #1, it's a strong signal. EDR tooling helps correlate this across a fleet rather than eyeballing one box at a time.
3. DNS anomalies
Repeated lookups to unfamiliar or known-malicious domains. DNS monitoring is often the cheapest, highest-signal layer to add if you don't already have it.
Layered detection stack
EDR → suspicious processes/files on the endpoint
Network monitoring → unusual connections & traffic patterns
DNS monitoring → suspicious/repeated domain lookups
SIEM → correlates all of the above into one signal
None of these alone is reliable. Together, they let you connect small anomalies into a confirmed incident.
Prevention checklist
- Patch aggressively a large share of botnet infections exploit known, already-patched CVEs. End-of-life routers are a favorite target (CISA has flagged this specifically).
- Kill default accounts and unused services on network devices.
- Enforce MFA everywhere you can.
- Segment your network so one compromised device isn't a straight line to everything else.
If you find an infected device
- Isolate it immediately pull it off the network before anything else.
- Investigate before you clean how did it get in, what malware, were credentials exposed, did it touch other devices?
- Don't assume deleting the malicious file is enough. Botnet malware frequently ships with persistence mechanisms cron jobs, scheduled tasks, modified startup scripts. Check logs, not just the obvious file.
4. Have an incident response plan before you need one. Root-causing under pressure is how you miss the second backdoor.
Adapted from a longer piece originally published on Diginatives.
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