"…You can think of Conficker as being the state of the art in conventional malware. It not only uses an important vulnerability, but it’s a sophisticated blended attack, using a wide variety of mechanisms to spread: pseudo-random domains, dictionary attacks on weakly-protected network shares, USB drives and more. You can admire the work that went into developing Conficker once you get past the amorality and greed that inspired it.
But there’s nothing that it does that you can’t protect against with best practices. Almost everyone who was hit by it was running a version of Windows XP that hadn’t been patched in many months. And even if you ran no anti-virus at all, least-privilege, updated software versions and a few other little things such as a good firewall would block most of the ill effects of Conficker and most other malware and prevent them from becoming permanent on the system." – Content courtesy of Malware Is Getting Formidable, but So Are Your Defenses