Please browse to  Guidance on Incident Handling and Security Tools for additional recommendations.

• Remove the host from RUNet immediately.
• Review the procedures for Compromise of Confidential or Sensitive Data.
• Check for signs of intrusion.
  • Windows Intruder Detection Checklist
  • The Intruder Detection Checklist targets UNIX systems
  • The Fundamental Computer Investigation Guide For Windows introduces basic forensic techniques for Windows hosts.
• Be aware of any notification requirements for regulatory compliance.
• Determine whether any confidential or sensitive data was compromised and respond accordingly. 
• Follow the Steps for Recovering from a UNIX or NT System Compromise. A short summary of the recommendations includes the following:
  • reformat the hard drive(s)
  • re-install the operating system from known good media
  • install anti-virus software
  • install current operating system and application patches
  • harden the operating system