Downadup Worm Affects More Than 10 million PCs Worldwide, Biggest Botnet Ever?

January 2009 is shaping up to be one of the worst months ever as the Cornficker or Downadup worm is said to have infected more than 10 million computers worldwide and could become the biggest botnet network ever according to some experts.

F-Secure reported that nearly nine million computers were compromised on Friday 16th at 2PM GMT, a near four fold increase in 100 hours or so, that's roughly 67700 new PCs turning to Zombies every hour (or 1.625 million per day).

At this rate, the botnet will have doubled in size to reach nearly 20 million by the end of the week, at least two orders of magnitude compared to previous bonets.

There are indications that whoever are behind the attack is about to modify the worm's code to make it more aggressive.

One trick that Cornficker is employing is the use of brute force password attacks to crack open home networks through the use of removable USB drives and other flash memory; this means that even patched PCs could potentially fall prey to the virulent malware.

According to Symantec, the overwhelming majority of affected computers are found in emerging countries like South America, Russia and South East Asia.

The core business of the criminals behind Downadup is rather than phishing information from the host computers, they are being used to disseminate malware and scareware that trick and persuade potential buyers to buy fake antivirus and other security software by bombarding them with bogus security alert pop ups.

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Our Comments

We would urgently advise you to download Microsoft's new malicious software removal tool (available here) to check whether there is any malware on your computer. If you don't have admin access, you can always use free online tools from Trendmicro or Secunia.

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