McAfee sites lower fees and less strict requirements to acquiring some of the above mentioned TLDs as a reason why they are more likely to be used for malicious purposes. Considering how easy it is to register a .com, I wonder how much less strict the requirements could become. They also pinpointed “security lapses” in the systems of some registrars, which also contributed to the figures. They didn't mention specific names, however.
The “safest” TLDs probed were .gov, reserved for Government use, .jp, for servers based in Japan, and .au, for servers based in Australia. Perhaps the registrars for .hk should take notes from how they hand out domains.