Through work I recently came across a server that is used by 10-20 users daily as a sort of web server. It is running Ubuntu 12 and it has not been updated for a very long time it seems. Currently there are over 300 security updates waiting to be installed.
I am have used Ubuntu for years and offered to perform upgrades and maintenance work on the server over a weekend when I could fix any potential problems. However I got a firm no as a response and it was explained to me that there was very little risk involved as the server only runs on the local network.
Could this be correct? What risks should be considered when running a server on a local network that is never updated?
The server in question does make requests out from the network to download information from other web servers. Users using the server have internet access on the same network. Ports for web, ssh and ftp access are open on the local network only and are password protected.