Now we have a better idea of how many computers are infected with malicious software ("malware"). Microsoft Corporation developed the MSRT (Malicious Software Removal Tool) back in 2004, and put it into use in January 2005. Over the next fifteen months, MSRT scanned 270 million PCs, and found that about 2.1 percent of them had some malware on them. The actual infection rate was probably a little higher, more like three percent, since Microsoft malware experts admitted that they did not know enough about all the malware out there to identify every one of them. But they did know how to find the vast majority of it. More worrisome was that 62 percent of the infected machines had a Trojan horse type program, that allowed someone else to take over that computer remotely, and turn it into a "zombie" for spamming or DDOS attacks to shut down another site. What's interesting about this is that it indicates there are about two million zombie PCs out there. Based on the size of zombie botnets already taken down (when their owners were caught and arrested), there are not that many really large (tens of thousands of zombies) botnets. That's sort of reassuring. It was also discovered that more defensive software makes a difference. The latest version of Windows (SP2), had a much lower rate of infection than earlier versions of Windows.
The military, especially in the U.S., but worldwide as well, are increasingly dependent on PCs and the Internet. Military nets are often more vulnerable than corporate ones, because companies usually have better management, and more effective safeguards against Cyber War threats.