Your PC is a great tool for productivity and entertainment. But does it have a secret life? Could it be part of an army led by a criminal mastermind?

OK, maybe it’s just led by a scummy spammer. But the army part could certainly happen.

I’m talking about botnets. These are malware-infected computers wrangled into rogue networks. The computers can be controlled by a single entity. They can be used to distribute malware, send spam and attack other networks. You computer can be pressed into the service of a botnet.

You computer will not announce that it’s been compromised. Botnets tend to be really discrete. Upon infecting computers, they don’t necessarily do anything. They simply await orders from the Web. They only jump into action when they receive those instructions.

That can make it difficult for security programs to identify botnet infections. Malware can be widespread before security programs are updated. Plus, the malware itself can receive updates to help it avoid detection.

Computers sometimes show signs of botnets. Has it suddenly and drastically slowed? The botnet may be hogging your computer’s resources. Has your browser home page been changed? The malware may be trying to contact its operator. Is your security software failing to update? The infection may be protecting itself from detection.