Security researchers report a new worm named Conficker.a (but also known as Downad.a and Downadup) is building a massive botnet. The worm exploits a critical Windows bug that was patched with an emergency fix in late October, and has already infected around 500,000 PCs.
Ivan Macalintal, a senior research engineer with Trend Micro Inc., said that the worm, which his company has dubbed "Downad.a" -- it's called "Conficker.a" by Microsoft and "Downadup" by Symantec Corp. -- is a key component in a new botnet that criminals are creating.
"We think 500,000 is a ball park figure," said Macalintal when asked the size of the new botnet. "That's not as large as some, such as [the] Kraken [botnet], or Storm earlier, but it's still starting to grow."
Last week, Microsoft warned that the worm was behind a spike in exploits of a bug in the Windows Server service, which is used by the operating system to connect to network file and print servers. Microsoft patched the service with an emergency fix it issued Oct. 23, shortly after it discovered a small number of infected PCs in Southeast Asia.