• perldoc perlsec
  
• Super Search
  
• The Camel Book
  
• Security sites (securityfocus, phrack, checksum...)
  To name few sources, should give you enough details about
  
  
  • Taint checking
  • Right checking
  • Race conditions
  • Authentication/encryption
  • Data validation (buffer overflow, escape characters, NULL poison, format strings...)
  • Advices about unsecure protocol using plaintext password (ftp, pop3...)
  • ...

"Only Bad Coders Code Badly In Perl" (OBC2BIP)