How to keep your home computer malware free.
How could it happen?
Clicking a link or attachment in email.
Visiting a website that has malware installed. Depending on your browser settings and what plug-ins you have installed (Flash, Java, Acrobat Reader) malicious software could be installed on your computer without out you knowledge.
What could happen?
You could loose all the data on your computer.
All the data on your computer could be held for ransom.
Your computer could be used to commit crimes.
Your personal information could be stolen.
Someone could access all of your accounts.
Someone could log everything you type.
Someone could access all the files on your computer.
Prevention
Update your operating system and third party applications.
http://secunia.com/vulnerability_scanning/personal/ Disable auto run for Plug-Ins
In Google Chrome navigate to chrome://settings/content.
Under Plug-ins select Click to play.
You can add exceptions by going to chrome://settings/content, Plug-ins, and clicking "Manage exceptions..."
Use a DNS server that blocks known malicious sites
Symantec
https://dns.norton.com/Comodo
https://www.comodo.com/secure-dns/ Use Windows Defender on Windows 8 or Microsoft Security Essentials on Windows 7
They are free and affective.
Buy and install MalwareBytes Premium and Malware Bytes Anti-Exploit Premium ($25 Each)
Be suspicious about links and attachments in emails. Don't click them.
Backup your data
Use BitTorrent Sync to sync your data with another computer.
Use and application like Acronis TruImage to make a scheduled backup to an external drive. Get two external drives and rotate them regularly. Keep one copy at a different location.
Use a cloud based backup service like Carbonite, Crashplan or Backblaze.
Consider replacing your current router with with a UTM (Unified Threat Management) firewall that has security software built in. Note that most of these are relatively expensive and require ongoing subscriptions.
Example
http://www.asus.com/support/FAQ/1008719/Be careful with remote access to your PC
Don't use VNC to remotely access your PC. Passwords are easily brute forced via automated scanning scripts. For best security consider two-factor authentication.
