Antivirus company “Dr. Web” conducted a study in order to trace the distribution of the Trojan, known as Flashback. This virus infects the machined based on Mac OS X. Flashback is distributed with the help of social engineering and exploitation of Java vulnerabilities. The last modification of malicious program contains an exploit for vulnerability CVE-2012-0507 that was eliminated in February 2011 for Windows-based systems. Once it became known that this flaw was actively exploited to compromise systems based on the Mac OS X, Apple released an update and fixed the vulnerability.
According to “Dr. Web”, today Flashback botnet includes more than 550,000 infected computers. Most of them are located in the U.S. and Canada. The experts made a list of malicious sites that are frequently used to infect vulnerable systems:
At the end of March one could find over 4 million of infected web-pages in Google search results. Moreover, according to unofficial sources, there were cases of infection by Flashback Trojan, while users were visiting dlink.com.
The researchers note that the virus uses a unique mechanism for creating addresses of command servers, which allows distributing the load between them, when it is needed. Each bot gets a unique identifier and this has helped “Dr. Web” to determine the numbers of affected machined using the sinkhole-method.