1 in 5 Windows PCs still hackable by Conficker

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Conficker Worm

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More: Malware Knowledge Center

Computerworld - Although the media blitz about the Conficker worm prompted a significant number of enterprise users to finally fix a six-month-old Windows bug, about one in five business computers still lack the patch, a security company said today.

Scans of more than 300,000 Windows PCs owned by customers of Qualys Inc. show that patching of the MS08-067 vulnerability -- a bug that Microsoft fixed with an emergency update issued in October 2008 -- picked up dramatically two weeks ago.

"The media attention about the April 1 date got people scanning like crazy," said Wolfgang Kandek, Qualys' chief technology officer, referring to the trigger date hard-coded into Conficker, the worm that used the MS08-067 vulnerability to infect millions of machines earlier this year. "We saw three to four times more scans [for the worm] than usual on March 30."

Qualys, like several other security vendors, had issued a Conficker detection tool prior to April 1, when the worm was set to switch to a new communications scheme for instructions from its hacker overlords.

The percentage of scanned PCs vulnerable to the MS08-067 bug began falling April 1, said Kandek, and within several days it had dropped from about 40% to just under 20%. "The whole thing about April 1 was a good thing," Kandek said. "Before [April 1], the number of machines still vulnerable to MS08-067 was probably comparable to other Microsoft vulnerabilities. Now it's better than average."

But even with the additional attention Conficker and the MS80-67 bug have received, about one in every five PCs scanned by Qualys remains unpatched. "I don't know why that is," Kandek said. "They could be older machines, or machines not considered important, or even Windows running on an ATM. Whatever it is, it's hard for me to understand why they're not patched."

Qualys' scans also revealed that about 5% of the PCs pinged were actually infected with one of the four Conficker variants. "That's a relatively low number, but because the Conficker numbers are staggering -- it's infected millions -- it's really a sizable number," said Kandek.

Last week, Conficker's handlers began updating already-infected PCs and used the opportunity to also install spam bots and phony antivirus software on those systems. Conficker.e, as the new variant has been dubbed, restores the worm's ability to spread to machines not yet patched against the MS08-067 vulnerability.

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