How malware works
Malware first needs to reach a device. Common delivery routes include phishing attachments, malicious links, infected downloads, removable media and exploitation of unpatched vulnerabilities. Once executed, it may install itself persistently, disable security tools, and contact a command-and-control server for instructions.
What happens next depends on the family. Ransomware encrypts files, infostealers harvest passwords and session tokens, backdoors give remote access, and loaders download further tools. Many modern strains run in memory or abuse legitimate system utilities to avoid signature-based detection. Some strains also spread automatically across shared drives.
Why it matters for Canadian organizations
Malware is a leading route to incidents that trigger breach obligations. Under PIPEDA, organizations must report breaches of security safeguards that pose a real risk of significant harm and keep records of them. Quebec's Law 25 adds its own incident duties.
Canadian organizations of every size are targeted, because attackers automate delivery at scale. The Canadian Centre for Cyber Security regularly publishes alerts on malware campaigns, and smaller firms with limited staff are often hit because their defenses are thinner. Reporting incidents quickly to your security provider and, where appropriate, the Canadian Centre for Cyber Security helps limit harm.
How to defend against it
Layer defenses. Keep operating systems and applications patched, use endpoint detection and response rather than signature-only antivirus, filter email and web traffic, and restrict administrator rights. Maintain tested offline backups so recovery does not depend on the attacker.
Add monitoring and training. A 24/7 security operations capability can spot unusual process behaviour and contain infected hosts quickly, while regular awareness training and phishing simulations reduce the chance that an employee launches the payload. Test restores regularly, because untested backups often fail when they are needed most.
Frequently asked questions
What are the main types of malware?
Common types include viruses, worms, trojans, ransomware, spyware, adware, rootkits, keyloggers and fileless malware. They differ in how they spread and what they do, but all run without the owner's informed consent. Each type behaves differently and needs different controls.
Is antivirus enough to stop malware?
Not on its own. Traditional antivirus relies heavily on known signatures and misses new or fileless threats. Layered controls such as patching, EDR, email filtering, least privilege and backups give far better protection. Layered defenses matter more than any single product.
How do I know if my computer has malware?
Warning signs include unexpected slowness, unknown programs, disabled security software, odd network activity and locked files. Many infections show no symptoms, so organizations rely on endpoint monitoring rather than users noticing. Slowness alone is a weak indicator, so continuous monitoring is more reliable.
Related service: Cyber defense