Which malware type specifically encrypts files and demands a ransom for their release?

Ransomware is a type of malware specifically designed to encrypt files on a victim's system, rendering them inaccessible until a ransom is paid to the attacker. The attacker typically provides instructions on how to pay the ransom, often in cryptocurrency, to ensure anonymity. This methodology creates a financially motivated scheme where victims may feel compelled to pay the ransom in hopes of regaining access to their important data.

In contrast, Trojan horses do not inherently encrypt files; they disguise themselves as legitimate software to gain access and can create various security issues. Worms are self-replicating malware that spread across networks but usually do not focus on file encryption for ransom purposes. Spyware is primarily concerned with collecting sensitive information without the user's consent, such as login credentials, rather than encrypting files for ransom.

Thus, ransomware stands out among these types as it specifically targets files for encryption in exchange for financial gain.