The 4.5 million PCs have become victims over the last three months following the appearance of the fourth version of the TDL virus.
The changes introduced in TDL-4 made it the "most sophisticated threat today," wrote Kaspersky Labs security researchers Sergey Golovanov and Igor Soumenkov in a detailed analysis of the virus.
"The owners of TDL are essentially trying to create an 'indestructible' botnet that is protected against attacks, competitors, and anti-virus companies," wrote the researchers.
4.5 million infected by highly sophisticated TDL-4 virus
Posted on Thursday, June 30 2011 @ 22:17 CEST by Thomas De Maesschalck
BBC News reports security researchers estimate 4.5 million PCs have fallen victim to the TLD-4 virus over the last three months. The TLD-4 botnet is deemed the most sophisticated threat today, it's well protected against attacks, competitors and anti-virus companies. The virus hides in Windows's master boot record, uses a custom encryption system to protect communication between those controlling the botnet and sends out instructions via a public peer-to-peer network rather than centralised command systems.