Machine encryption is the process of making files or systems unusable without a key that can decrypt them. In ransomware attacks, malicious software may encrypt data on one device and, if it can reach other systems, spread the impact across multiple machines. Encryption can disrupt work even when there is no evidence that data was stolen.
Defenders reduce the risk and impact by limiting access between devices, controlling credentials and remote connections, monitoring for unusual file changes, and isolating suspicious machines quickly. Reliable, offline or otherwise protected backups can help restore affected systems, though recovery depends on the scope of encryption and the integrity of those backups.