It's possible that there is some form of infection, but it's hard to know for sure. With spyware and bots constantly evolving, users can become infected with a rare strain that antivirus and antispyware tools don't pick up, or that aren't evil enough to justify a signature. While antivirus and antispyware tools are certainly helpful in protecting machines, they focus on detecting widespread malware that is truly malicious. They don't do well with targeted attacks that are based on custom malware, or malware specimens that aren't widespread. Also, what one person considers resource-hogging spyware, another person may consider an interesting and useful application. Thus, it's not always clear which specimens the antivirus and antispyware tools should detect. That's why it can be immensely helpful to get a second opinion, just as one would for a serious medical condition.
To get such an opinion, I recommend running a scan using a free antivirus tool, such as Clam AV, and a free antispyware tool such as Lavasoft's Ad-aware. Run a scan with these tools to see if they pick up something that existing antivirus tool don't. Users also may want to run a scan using Microsoft's free malicious software removal tool. Although it's not as comprehensive as most antivirus and antispyware tools, it's excellent at removing some of the most pernicious malware specimens out there today, and it's updated fairly regularly.
Dig Deeper on Malware, virus, Trojan and spyware protection and removal
Related Q&A from Ed Skoudis
At Black Hat 2006, researcher Joanna Rutkowska unveiled a piece of machine-based malware called the Blue Pill. But is it a serious threat to your ... Continue Reading
Wi-Fi on airplanes seems like it will be unavoidable in the future, but what security risks does it pose? In this security threats expert response, ... Continue Reading
By viewing a page's HTML source code and writing malicious scripts to a drop-down list, hackers may be able to re-post the malicous page to the ... Continue Reading
Have a question for an expert?
Please add a title for your question
Get answers from a TechTarget expert on whatever's puzzling you.