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Most home security advice focuses on protecting your own data and privacy — reasonably so. But there's a separate, less-discussed risk that has little to do with what happens to your information and everything to do with what your devices might be quietly doing to someone else's network without your knowledge.
What a Botnet Is
A botnet is a network of compromised devices, controlled remotely by an attacker, typically used to carry out coordinated actions at scale — most commonly distributed denial-of-service (DDoS) attacks, where thousands or millions of devices simultaneously flood a target server with traffic, overwhelming it. Individually, one compromised device sending a modest amount of traffic barely registers. Combined across a huge number of devices, the effect can take down major websites and services.
Why IoT Devices Make Attractive Targets
Internet-connected home devices — cameras, DVRs, routers, smart plugs, and similar — have become a favored target for botnet recruitment for a few consistent reasons: many ship with default or weak credentials that are never changed after setup, many run outdated software with known vulnerabilities that go unpatched for years, and unlike a personal computer, most people never notice unusual background activity on a smart camera or plug, since these devices don't have an obvious interface showing you what's happening internally.
The Mirai Botnet, Briefly
The most widely cited example is Mirai, malware first identified in 2016 that scanned the internet for IoT devices still using default factory credentials, logged in, and recruited them into a botnet. At its peak, Mirai was linked to some of the largest DDoS attacks recorded up to that point, including one that disrupted major internet services across parts of the US by targeting a DNS provider. The source code was later released publicly, which led to numerous variants continuing to circulate and target similar device weaknesses for years afterward.
How a Device Gets Recruited Without You Noticing
The process typically doesn't require any action from the device's owner, and often produces no visible symptoms at all:
- Automated scanning tools continuously probe internet-connected devices, testing for default or common credentials and known unpatched vulnerabilities.
- Once access is gained, malware installs itself, often designed to survive quietly and avoid drawing attention.
- The device then waits for instructions from a remote command server, periodically checking in, and can be activated as part of an attack at any time.
- The device's regular function usually continues working normally throughout, which is precisely why owners rarely notice anything is wrong.
Why This Matters Even if Your Own Data Isn't at Risk
It's tempting to think "I don't have anything valuable on my smart plug, so who cares" — but a botnet-recruited device isn't really about what data it holds. It's being used as infrastructure for attacks against unrelated third parties, and depending on your internet provider's terms of service and how the compromise is discovered, a compromised device on your network can also result in service warnings or restrictions from your ISP, since the outbound traffic pattern is often what first flags a household's connection as compromised.
Practical Steps to Reduce Your Device's Risk
- Change default credentials immediately on any new smart device, especially cameras, DVRs, and network video recorders, which are frequent Mirai-style targets.
- Keep device firmware updated where the manufacturer offers updates, and check periodically for older devices that might not update automatically.
- Put smart devices on a separate guest or IoT network, discussed in our guide to guest networks and segmentation, which limits what a compromised device can reach even if it is recruited.
- Avoid exposing device management interfaces directly to the internet unless genuinely necessary, and disable remote access features you don't use.
- Retire devices that no longer receive updates, particularly older, cheaper cameras and DVRs from manufacturers with limited long-term support history.
Frequently Asked Questions
How would I know if one of my devices was part of a botnet?
Often you wouldn't, from the device's normal behavior alone, since the underlying function usually keeps working. Occasionally you might notice unusual network activity, a slower connection than expected, or in more serious cases, a notice from your internet provider about unusual traffic from your connection.
Are cheap, off-brand smart devices more at risk than well-known brands?
Generally, yes, as a pattern rather than a guarantee — lesser-known manufacturers more often ship with weak default security and provide limited or no ongoing firmware updates, both key factors that made devices attractive Mirai targets. That said, established brands aren't automatically immune, so basic precautions still matter regardless of brand.
Does antivirus software protect smart home devices like it protects a computer?
Not typically — most IoT devices don't support installing antivirus software directly, since they run limited, purpose-built operating systems. Protection instead comes from network-level precautions like segmentation, strong credentials, and keeping firmware updated.