A strain of spyware that displays pornographic pop-ups has retained its place as the top spyware nuisance on the net last month. ISTbar was responsible for 3.5 per cent of infections detected by Panda Software's free online malware scanner, more than any other spyware or adware application.

ISTbar, which poses as an ActiveX control, acts as an entry-point for other malware, adware and dialers. It also displays pornographic pop-ups, installs a toolbar and changes the home page of browsers on infested PCs.

Cydoor, an adware program that downloads advertisements from a server and displays them on PCs, made runner-up spot on Panda's June list of spyware nasties as nabbed by Panda's ActiveScan service, which was recently upgraded to add spyware detection alongside its existing virus busting features. Panda's June spyware chart features only one new entry, an adware package called MarketScore.

Spyware refers to a class of invasive program that generates pop-ups, hijacks user home pages or redirects searches in an attempt to either monitor user activity or bombard surfers with unwanted messages. It's a fast growing category that is beginning to eclipse more clear-cut malware - such as computer viruses - in economic impact if not in prevalence. ®

Top spyware threats, as compiled by Panda Software

1. ISTbar
2. Cydoor
3. New.net
4. XXXToolbar
5. Dyfuca
6. BetterInet
7. Petro-Line
8. Altnet
9. BargainBuddy
10. MarketScore

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