Botnet malware, Kelihos, is now spreading via infected thumb drives, researchers said.
Over 2016, the botnet’s activity ramped as tens of thousands of new bots ended up added to it.
Kelihos was sending out MarsJoke, Wildfire, and Troldesh ransomware and Trojans like Panda Zeus, Nymain and Kronos.
The botnet ends up rented out as a part of the “spam as a service” business model and continues to geo-target users. The latest campaign targeted users in Canada with links to web pages of Tangerine Bank phish websites, while distributing a link to the Ecstasy website to recipients with “.kz” email addresses, said Arsh Arora, malware analyst and Ph.D. researcher at The University of Alabama at Birmingham.
The emails contain a webpage that attempts to trick the user into clicking a button with the subject line of “TANGERINE online account has been suspended” (where Tangerine is the Internet/telephone base bank formerly known as ING Direct). An HTML version of the page is displayed to the potential victims, encouraging them to click on a “Learn More” button, which would take them to a phishing site, in an attempt to steal their credentials by requesting them to verify their information.
The geo-tagging of addresses ending with “.kz” is something new for the Kelihos botnet, Arora said. The spam message, which featured a subject line in Russian, was directing users to an adult site.
As a part of the attack, removable drives attached to the compromised machines would end up infected with a copy of the original Kelihos binary. Arora said the malware was written to a thumb drive connected to the virtual machine infected as part of the new campaign.
Saved on the thumb drive under the name of “porn.exe,” the executable is hidden from the user, the same as a few shortcuts not present on the removable device before. The file is the Kelihos botnet, Arora said.
The researcher also found the Create File function linked to the dropped executable. The malware attempts to open several files with CreateFile and, if it fails, it then reverts to creating the .exe file, after which it writes the malicious binary to this file. Next, the malware creates shortcuts for the hidden directories and executables.