Kaspersky Lab researchers say the Kelihos botnet, which was taken down last fall, is back.

"Researchers knew that it would only be a matter of time before its controller used the botnet's complex infrastructure of proxy servers and communication nodes to regain control. ... 'We could have issued an update to those machines to clean them up, but in several countries that would be illegal,' said Ram Herkanaidu, security researcher and education manager for Kaspersky Lab," writes Computerworld's Jeremy Kirk.

"Meddling with another person's computer could be considered a form of hacking, even with the best intentions of security researchers," Kirk writes. "Unfortunately, it appears that many of the machines infected with Kelihos are now controlled by the bad guys again."

Go to "Kelihos botnet, once crippled, now gaining strength" to read the details.

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