Pat Peterson, a security researcher and fellow at Cisco Systems Inc., says sophisticated attackers have also been adding a more subtle approach to evade detection.
Instead of directing huge amounts of traffic at a target site, they'll make more complicated requests one at a time that eat up more of the site's computing power, like trying to log in using bogus usernames and passwords. If enough of those requests are made, on a site that requires a lot of computing power, the effect can be the same, and the site gets knocked out.
This type of attack is trickier because it doesn't involve the sort of massive traffic surge that would normally tip off network administrators.
This advanced tactic wasn't necessarily used in the most recent attacks. In fact there are signs the attacks were relatively amateurish. The programming code appears to have been patched together largely from material that has been circulating in the criminal underground for several years, according to Jose Nazario, manager of security research for Arbor Networks.
Q: If these attacks make use of compromised computers corralled into a "botnet," should I be worried about whether my PC is one of them? What could I do to prevent that or fix it?
A: If your computer is being used in a denial-of-service attack, you're likely to see a significant slowdown, because your processing power is being siphoned for the assault. But there aren't always obvious signs that your computer has been infected.
So the best thing is to focus on prevention, namely by having up-to-date antivirus software. In particular, make sure your antivirus software gets updated over the next few days.
If you're concerned your machine might be infected, it's wise to run an antivirus scan. Many antivirus companies offer a free scan from their Web sites.
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