What is Malware?

How Malware Works

Malware reaches a target through an infection vector: a phishing email with a malicious attachment, a compromised website exploiting a browser vulnerability, an infected USB drive, or software bundled with legitimate-looking downloads. Macro-based attacks embed malicious scripts inside Office documents that execute when the file opens.

Once on a system, malware establishes persistence through registry modifications, scheduled tasks, or rootkit installation that hides its presence from the operating system. Some variants use polymorphism, rewriting their own code to evade signature-based detection. Fileless malware skips disk writes entirely, running in memory through legitimate processes like PowerShell or WMI.

After persistence, malware connects to a command-and-control (C2) server for instructions. Ransomware begins encrypting files and drops a ransom note. Spyware and keyloggers exfiltrate credentials through encrypted channels. Worms self-replicate across the network, scanning for vulnerable hosts without any user interaction. Organizations with flat network architectures are especially exposed to rapid lateral movement that effective endpoint threat detection can interrupt.

Why Malware Matters

Without layered defenses, malware reaches endpoints, encrypts production data, and extracts credentials before most organizations detect the infection. Malware volume rose 2% in 2022 after three consecutive years of decline, with IoT malware up 87% and cryptojacking hitting a record 139.3 million attacks (SonicWall, 2023). Ransomware remains a leading breach type, contributing to a global average breach cost of $4.99 million in 2026 (IBM Cost of a Data Breach Report 2026). 

For IT teams running lean, malware creates a compounding problem. Antivirus misses polymorphic and fileless variants. Backup integrity fails when malware has already corrupted the recovery path. Effective containment requires network segmentation, verified immutable backups, and a defined disaster recovery plan with tested recovery objectives working together. Organizations relying on signature-based tools alone face an expanding detection gap as malware volume and sophistication grow.

Malware vs. Virus

Malware is the correct umbrella term. Virus is one specific subtype. Calling ransomware a "virus" is technically inaccurate and creates confusion during incident response.

Common Misconceptions

Malware is not a Windows-only problem. macOS, Linux, Android, and iOS all face malware targeting their specific architectures, including documented mobile banking trojans, macOS adware, and Linux-based cryptominers.

Malware does not always announce itself with visible symptoms. Sophisticated variants, particularly spyware, keyloggers, and cryptominers, operate silently for weeks or months. Behavioral monitoring through 24/7 security event analysis is more reliable than waiting for user-reported symptoms.