Trojan-Downloader:OSX/Flashback is a family of malicious applications which when installed on a computer will download a payload from a remote site, then modify targeted webpages displayed in the web browser. Variants in the Flashback family may include additional malicious functionalities or characteristics.
Disinfection & Removal
Free Removal Tool
11 April 2012: F-Secure now provides a free removal tool that automates the detection and removal of Flashback variants from an infected machine.
Further information and download of the tool is available in the following Labs Weblog post:
Keep your Mac protected against the latest threats with F-Secure Anti-Virus for Mac. Try it now for 30 days for free.
Disinfection instructions for Flashback trojans differ depending on the specific variant present on the machine. Please refer to the individual descriptions for each detected variant (seeAdditional Details below) for specific removal instructions.
Early Flashback variants disguised themselves as Flash Player installers in order to trick users into installing and executing them.
Subsequent Flashback variants no longer use social engineering tactics to ensure distribution; instead, they are dropped by malicious Java applets exploiting known vulnerabilities, thereby requiring no user action for infection to occur.
Additional technical details are available in the following Labs technical paper: Flashback OS X Malware (PDF)
For more information, please see the individual descriptions for the variants detected:
This malware family is also further discussed in the following Labs Weblog posts:
- October 5, 2012: VB2012 Paper: Flashback OS X Malware
- May 2, 2012: Oxford Muses on Mac Flashback: Worst Outbreak Since Blaster
- April 11, 2012: Flashback Removal Tool
- April 5, 2012: Mac Flashback Infections
- April 2, 2012: Mac Flashback Exploiting Unpatched Java Vulnerability
- March 23, 2012: Are you having a (Mac) Flashback?
- March 19, 2012: Mac Malware at the Moment
- October 19, 2011: Mac Trojan Disables XProtect Updates
- October 12, 2011: Mac Trojan Flashback.B Checks for VM