I need to persuade "the management" that running two or more unrelated business-critital applications within a single shared runtime environment (i.e. a single "command line") is a really bad idea. Problem is the management doesn't recognise "the security-freak guy authority" (me) and wants my cause to be backed by some recommendation from an actual autority such as ISO, ISACA, NIST or any other three-to-four-letter-agency.
Is there a defined "best practise" or requirement in any of the security standards that would clearly state that running two or more separate and unrelated applications (such as database processes) in a single shared runtime environment with the same UID is wrong?
Please note that I know it's a bad idea and I can come up with many reasons to back this claim but none of these include a quote from "a standard".