In the context of intranet and internet services, you might be interested to protect you PeopleSoft applications from external users and possible threats.
You can probably prevent big issues if you technicaly lockdown some sensible features.
With "PeopleSoft WebLogic Application Firewall" this is possible to add an extra security level on the Web server layer (WebLogic).
This does not exempt having a strong PeopleSoft user security !
To enforce security you have to identify in a list - the WhiteList - the PeopleSoft Components that you allow from internet.
By default all other Components will be unauthorized.
If you have interest in this feature, I can provide a link to download it for free.