Useful tips / procedures how to prevent virus do for attacking your PC from US-CERT :
- Do not follow unsolicited web links in email messages or submit any information to webpages in links
- Use caution when opening email attachments. Refer to the Security Tip Using Caution with Email Attachments for more information on safely handling email attachments
- Maintain up-to-date anti-virus software
- Perform regular backups of all systems to limit the impact of data and/or system loss
- Apply changes to your Intrusion Detection/Prevention Systems and Firewalls to detect any known malicious activity
- Secure open-share drives by only allowing connections from authorized users
- Keep your operating system and software up-to-date with the latest patches
- Refer to the Recognizing and Avoiding Email Scams (pdf) document for more information on avoiding email scams
- Refer to the Security Tip Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks
Also, US-CERT suggests the following possible mitigation:
- Immediately disconnect the infected system from the wireless or wired network. This may prevent the malware from further encrypting any more files on the network
- Users who are infected should change all passwords AFTER removing the malware from their system
- Users who are infected with the malware should consult with a reputable security expert to assist
- Removing the malware, or users can retrieve encrypted files by the following methods:
- Restore from backup
- Perform System restore
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