BBC is running a story that has the  Top 20 computer threats unveiled which covers both Windows and Unix/Linux. Here are the top 10 Windows threats:

  1. Web servers & services
  2. Workstation service
  3. Windows remote access services
  4. Microsoft SQL server
  5. Windows authentication
  6. Web browsers
  7. File-sharing applications
  8. LSAS
  9. E-mail programs
  10. Instant messaging

And the top 10 Linux/Unix threats:

  1. Bind domain name system
  2. Web server
  3. Authentication
  4. Version control systems
  5. Mail transport services
  6. Simple Network Management Protocol (SNMP)
  7. Open secure sockets layer (SSL)
  8. Misconfiguration of enterprise services
  9. Databases
  10. Kernel