Torrent client for mac virus code#

The first time it executes, KeRanger will create three files вЂњ.kernel_pidвЂќ, вЂњ.kernel_timeвЂќ and вЂњ.kernel_completeвЂќ under ~/Library directory and write the current time to вЂњ.kernel_timeвЂќ. When users click these infected apps, their bundle executable Transmission.app/Content/MacOS/Transmission will copy this General.rtf file to ~/Library/kernel_service and execute this вЂњkernel_serviceвЂќ before any user interface appearing.ДЇigure 3 The malicious executable pretends to be an RTF documentДЇigure 4 KeRanger executes the extra General.rtf fileДЄfter unpacking the General.rtf with UPX, we determined that its main behavior is to encrypt the userвЂ™s files and hold them for ransom. It uses an icon that looks like a normal RTF file but is actually a Mach-O format executable file packed with UPX 3.91. The KeRanger infected Transmission installers include an extra file named General.rtf in the Transmission.app/Contents/Resources directory.

Torrent client for mac virus code#

In the code signing information, we found that these installers were generated and signed on the morning of March 4.ДЇigure 2 Code signing information of KeRanger The developer listed this certificate is a Turkish company with the ID Z7276PX673, which was different from the developer ID used to sign previous versions of the Transmission installer. The two KeRanger infected Transmission installers were signed with a legitimate certificate issued by Apple. Palo Alto Networks has also updated URL filtering and Threat Prevention to stop KeRanger from impacting systems. Apple has since revoked the abused certificate and updated XProtect antivirus signature, and Transmission Project has removed the malicious installers from its website. Palo Alto Networks reported the ransomware issue to the Transmission Project and to Apple on March 4. Additionally, KeRanger appears to still be under active development and it seems the malware is also attempting to encrypt Time Machine backup files to prevent victims from recovering their back-up data. After completing the encryption process, KeRanger demands that victims pay one bitcoin (about $400) to a specific address to retrieve their files. The malware then begins encrypting certain types of document and data files on the system. KeRanger then waits for for three days before connecting with command and control (C2) servers over the Tor anonymizer network. If a user installs the infected apps, an embedded executable file is run on the system. The KeRanger application was signed with a valid Mac app development certificate therefore, it was able to bypass AppleвЂ™s Gatekeeper protection.

ItвЂ™s possible that TransmissionвЂ™s official website was compromised and the files were replaced by re-compiled malicious versions, but we canвЂ™t confirm how this infection occurred.ДЇigure 1 KeRanger hosted in Transmission's official website

When we identified the issue, the infected DMG files were still available for downloading from the Transmission site (hxxps:///files/Transmission-2.90dmg) Transmission is an open source project. As FileCoder was incomplete at the time of its discovery, we believe KeRanger is the first fully functional ransomware seen on the OS X platform.ДЄttackers infected two installers of Transmission version 2.90 with KeRanger on the morning of March 4. We have named this Ransomware вЂњKeRanger.вЂќ The only previous ransomware for OS X we are aware of is FileCoder, discovered by Kaspersky Lab in 2014.

On March 4, we detected that the Transmission BitTorrent client installer for OS X was infected with ransomware, just a few hours after installers were initially posted.