Blacklists have always been a significant tool in the security industry's anti-malware arsenal. For years, the basic anti-virus model was simply to maintain a list of known viruses (and their permutations) and match any potential virus against that list. As malware started to proliferate and vary wildly, security firms have augmented this approach with other techniques, though the basic blacklist still remains. Blacklists are also used to protect against spam and identify websites that may be hostile. But just as the model has come to be inadequate in the traditional anti-virus space, so too is it seen as deficient for other purposes
. Among the complaints about blacklists include the fact they're easy to accidentally fall into, while easily gamed by those looking to get off them. Essentially, blacklists are a blunt weapon unsuitable for the complexity of good security systems. Just ask the customers of Verizon, who at times have had all of their foreign email blocked, because the company's overly aggressive anti-spam software
. Interestingly, one major user of blacklists is Google, which uses them to warn users about potentially malicious sites that they may encounter through searches. Seeing as the company is ramping up its security business
, it will be worth watching whether it continues to push blacklists, or if it seeks out more sophisticated mechanisms for discerning what's legitimate online.