Legacy Systems


legacy system is one that is no longer directly supported by its vendor.

  • might be because:
    • vendor has gone out of business
    • or formally deprecated use of the product
  • product that is no longer supported is referred to as end of life (EOL)
  • Networks often need to retain hosts running legacy OSs and applications software or old-style mainframe computers to run services that are too complex or expensive to migrate to a more modern platform
  • Legacy systems usually work well for what they do
    • is why they don’t get prioritized for replacement
    • but they represent severe risks in terms of security vulnerabilities
  • If attackers discover faulty code that they can use to try to exploit the device, the vendor will not be available to develop a software patch to block the exploit
  • important to isolate them as far as possible from the rest of the network and to ensure that any network channels linking them are carefully protected and monitored