I am given few URLs (web service APIs), which when called would fetch and display data in JSON format and I am using these in my Salesforce Org and use them to update few of Salesforce fields. I have written an APEX controller to parse the data coming from the external application and then use it another main controller wherein the actions such as insert/update take place. Like, whenever a Lead record is opened, then a call is made to the external system using the URL provided, then fetch the data and insert/update data as per the need.
I am wondering if there could be a security be placed whenever there is a call made to the external system from Salesforce, as of now nothing of such is maintained and I assume there should be one existing and need suggestions on this.