Skip to main content

Zombie PCs Attack

By January 16, 2009June 17th, 2017Blog

Internet News published this article yesterday, about zombie PCs ( getting smarter and harder to track, as they are regularly asking for new IP addresses from their ISPs, ultimately rendering anti-spam software that works by blocking IPs now useless:

Unfortunately, my first thought reading through this is a big “I told you so” to the universe of security experts who keep insisting that IP reputation is the silver bullet in the ongoing war against spam and other e-mail bourn threats. Commtouch ( is a world recognized expert in the field of IP based reputation and should be taken at their word. If they say that IP reputation is finally dead, I would agree.

The fact that IP based reputation schemes are flawed has been well known to Sendio ( for years. We have always believed the only type of security that really works is active security. All of the current IP reputation schemes are passive/reactive; employing complex algorithms to make guesses based on patterns and probabilities. Clearly, in a world where there is big money at stake, the bad guys are highly motivated to find mechanism that allow them to evade these passive security paradigms.

I believe the time has come for the security community-at-large to recognize that we need to move away from passive guessing schemes to active authentication methodologies.