As a Microsoft employee, I try to avoid writing on areas that blatantly promote Microsoft. However, I think this question is generic enough to involve Microsoft in the discussion: Can IP addresses ever be used for statistical analysis of malicious Web sites?
I've been a malware fighter for more than 20 years. I consider myself fairly up-to-date on the subject of malicious mobile code, malware, hackers, and exploitation vectors in general.
So it was with surprise then that I read another of Google's recent studies purporting that IIS Web servers were twice as likely to contain malware as Apache Web servers (although Apache and IIS Web servers contained malicious Web sites in equal numbers).
This astounded me for several reasons. First, my personal experience tells me it isn't so. I run multiple IIS and Apache Web servers on my honeynet, and my Apache Web servers get 89 percent more hacking traffic than my IIS servers. Most of the traffic is PHP/CGI/MySQL based. This is not unexpected, as the Internet contains at least twice as many Apache Web servers, and popularity draws malicious hacking.
Second, in general and contrary to traditional wisdom, the average Apache Web administrator has less security knowledge than the average IIS administrator. I find Apache Web administrators much more likely to download and use dubious code from the Internet (which a previous Google study revealed often contained malware).
While both types of Web administrators, in general, really don't care about security, IIS is helped by the fact that it has had only three published vulnerabilities over the last four years, as compared to Apache's 33.
Even if we include application coding errors, ASP and ASP.Net compare favorably against PHP and CGI. PHP proponents are desperately trying to put more security into PHP, but there's a ton of insecure PHP applications out there -- just read one of the many vulnerability lists.
Maybe hackers are breaking in using SQL injection or back-end database vulnerabilities? MS-SQL hasn't had a severe vulnerability since 2003, while Oracle, MySQL, and other databases have had dozens to more than 100.
IIS 6 comes secure by default. Unless the administrator goes out of their way to make it vulnerable or unless the application adds a vulnerability, it's very secure. When Apache is installed, its defaults are more permissive and less secure.