Operation

Once installed, the rogue security software may then attempt to entice the user into purchasing a service or additional software by:
- Alerting the user with the fake or simulated detection of malware or pornography.
- Displaying an animation simulating a system crash and reboot.
- Selectively disabling parts of the system to prevent the user from uninstalling the malware. Some may also prevent anti-malware programs from running, disable automatic system software updates and block access to websites of anti-malware vendors.
- Installing actual malware onto the computer, then alerting the user after "detecting" them. This method is less common as the malware is likely to be detected by legitimate anti-malware programs.
- Altering system registries and security settings, then "alerting" the user.

Propagation

Rogue security software mainly relies on social engineering (fraud) to defeat the security built into modern operating system and browser software and install itself onto victims' computers. A website may, for example, display a fictitious warning dialog stating that someone's machine is infected with a computer virus, and encourage them through social engineering to install or purchase scareware in the belief that they are purchasing genuine antivirus software.
Most have a Trojan horse component, which users are misled into installing.

The Trojan may be disguised as:
- A browser plug-in or extension (typically toolbar)
- An image, screensaver or archive file attached to an e-mail message
- Multimedia codec required to play a certain video clip
- Software shared on peer-to-peer networks
- A free online malware scanning service.