All posts

1 min read

Malware: Viruses, Spyware, and Ransomware

Learn about viruses, Trojans, spyware, infostealers, and ransomware: how they infect, common symptoms, and what steps to take if you suspect an infection.

Translated from Turkish with AI.

Why It Matters

Malware transforms a device into an attacker's tool: it steals data, locks files, or is used for other attacks.

The Basics

  • Viruses and Worms: Self-replicating malicious programs; worms spread autonomously across networks.
  • Trojan: Appears to be a legitimate or useful program (e.g., pirated games, "free" software).
  • Spyware and Keyloggers: Monitor your keystrokes, screen activity, and passwords.
  • Ransomware: Encrypts files and demands a ransom. Today, most ransomware first steals data, then encrypts it, and threatens a second time with "we will publish it if you don't pay."
  • Adware and Potentially Unwanted Programs (PUPs): Appear less harmful but can open the door to more serious threats.
  • Infostealer: Steals saved passwords and session cookies from browsers; someone whose session cookies are stolen might find their account compromised despite Multi-Factor Authentication (MFA).

How it Spreads: Email attachments, fake updates, pirated software, malicious advertisements, vulnerabilities in outdated programs, unknown USB drives.

Symptoms: Sudden device slowdown, unfamiliar programs, browser homepage changes, strange messages sent from your account to friends, altered file extensions.

A Realistic Example

An employee downloads a "free" video editing program to their home computer. The program collects saved work passwords from the browser. A week later, the company's cloud account is accessed using these stolen passwords.

What to Do

  • Download programs only from official sources; avoid using pirated software.
  • Keep your operating system's built-in protection (e.g., Windows Security) enabled.
  • The strongest defense against ransomware is offline backups (see section 9).
  • If you suspect an infection, disconnect the device from the network and report it immediately; do not attempt to "clean" it yourself and erase evidence.

Remember: Software that appears free often costs you your data.

*This article is the 7th part of a 14-part Cybersecurity Awareness series.* Next up: Device security: computers, phones, Wi-Fi, and updates