How to recover from ransomware attack.
The best way to to recover from a Ransomware attack is to have a Recovery Plan.
- Isolate affected systems. Disconnect infected computers, servers, and storage from the network to prevent the ransomware from spreading.
- Preserve evidence. If the attack may require investigation, avoid deleting files or wiping systems before IT/security professionals have captured relevant evidence.
- Identify the ransomware. Determine which ransomware variant is involved and whether a legitimate decryptor is available.
- Remove the malware. Use trusted, up-to-date security software. For severely compromised systems, a clean OS installation or reimaging is generally safer than trying to remove every malicious component manually.
- Patch and secure systems. Before reconnecting restored machines, install current operating-system and application updates, change compromised credentials, and address the vulnerability that allowed the attack.
- Restore from clean backups. Use the most recent backup that you can verify was created before the ransomware infection. Don’t restore backups that may themselves be compromised.
- If necessary, restore a complete system image. A known-good image can be preferable when rebuilding a system manually would be impractical.
- Verify the recovery. Scan restored systems, check that applications and data work correctly, and monitor for signs of reinfection before returning them to normal operation.
- Investigate and improve defenses. Determine how the ransomware entered, document the incident, and strengthen backup, patching, authentication, network segmentation, and endpoint-security practices.
Important: Don’t assume that deleting the encrypted files will remove the ransomware. Also, avoid paying a ransom. Carefully consider the legal, operational, and security implications.
