Security and auditing are valid concerns, but dangerous topics to wander into.

My work has often been in larger shops; from a couple hundred servers, to a few thousand, and up to "we don't really know". Security, and auditing, varied. Early on "it works" was sufficient. Later, when corporate started listening to us talk about needing to upgrade and defend, internal and external auditing became more common. I won't say everything was perfect, but at least we could talk about things openly and management would listen.

However, Perl and CPAN quickly become issues. Large shops use a variety of "solutions", and those use a variety of languages and language tools. Large shops can seldom audit the tool chain. With CPAN, it becomes even more problematic; every module increases your vulnerability footprint and fragility. In general, a large shop has three options:

1. Pay for support for every language and every module used.
2. Pay for a large enough staff to support every language and module used.
3. Shift legal liability to the OS and Solution vendors since that's what they are paid for.

Any guesses as to which one usually gets picked? :P

Keep in mind, we've seen OS vulnerabilities that only affect "Version X and later." New versions of software can provide new functionality as well as increased performance, etc. However, that very "new" is an open invitation to new bugs and vulnerabilities. All software has bugs. New software has new bugs. Assuming newer is better is not a valid security posture.