What Is Ransomware: How It Works and How to Prevent It

Ransomware is an attack that encrypts a victim’s files or devices to make them inaccessible and demands a ransom in exchange for the decryption key. If the payment deadline passes, data leakage or permanent loss can occur, inflicting major financial and operational damage on organizations. The article notes that incidents have been observed since the mid-2000s.

Infection vectors are diverse, primarily including phishing emails, malicious links, deceptive ads and pop-ups, brute-force or exposed Remote Desktop (RDP) services, and drive-by downloads. After infection, attackers explore the system to find and encrypt valuable files. Because only the attacker holds the decryption key, victims are pressured to pay a ransom.

Recent features of ransomware attacks include double extortion—combining data theft and threats to publish stolen data—with attackers demanding payment to prevent disclosure, and the spread of RaaS, where attack tools are offered as a service. Families such as LockBit have carried out large-scale attacks. Historically, notable cases include the 1989 AIDS trojan, 2013’s CryptoLocker, and 2017 incidents like WannaCry and NotPetya.

Recommended defenses include avoiding untrusted links and attachments, keeping operating systems and software up to date, maintaining regular backups both locally and offsite (ideally offline or immutable when possible) and testing restoration, enforcing least privilege and network segmentation, disabling or updating risky plugins, implementing strong authentication (MFA), and providing employees with phishing awareness training.

Indicators for early detection include changes to file name extensions, mass file creation or locking, degraded system performance, on-screen ransom messages, and alerts from security software or IDS. Responding quickly to these signs is important to minimize damage.