I assume you are referring to PerlApp by AS. Use a C debugger, set a breakpoint in eval_pv() or something similar (I dont remember anymore) (finding eval_pv in the process will be the painful part), once the AS decompresser/obfuscator decrypts it into memory, it will be passed as 1 big string to the perl5**.dll which will be in a temp dir somewhere on disk.
The other choice is to RE the PerlApp obfuscator algorithm Re: Security, is it to much to ask?
. Its been published a couple times in history, for example A real challenge
and Decompile PerlApp
but AS changes it constantly for obvious reasons.