Banking Trojan developers are always finding new ways to spread malware and infect victims. Kaspersky found a new malware that targets users of over 60 banks in Brazil. It caught the attention because of its advanced infection method using various technologies, different from known banking Trojan infections.
The malware uses the Squirrel installer to spread and uses NodeJS and a newer programming language called Nim as a loader to infect systems. Kaspersky named this new Trojan “Coyote” because coyotes hunt squirrels. The Nim language is described as a “statically typed compiled systems programming language that combines successful concepts from mature languages like Python, Ada, and Modula.” The use of less popular and cross-platform languages by cybercriminals is a trend we identified in the report on Crimeware and financial cyberthreats for 2024.
Banking Trojans often utilize the Delphi language or MSI installers as a common method for initial infection. This is a well-known trend among malware creators in the cybersecurity community.
Coyote does things a little differently. Instead of going down the usual route with MSI installers, it opted for a relatively new tool for installing and updating Windows desktop applications: Squirrel. As the authors explain, “Squirrel uses NuGet packages to create installation and update packages, which means that you probably already know most of what you need to create an installer.”
Source: Securelist
By using this tool, Coyote hides its initial stage loader by presenting it as an update packager.
Source: Securelist
The Node.js loader script:
When Squirrel is used, it runs a NodeJS application with Electron. This application runs obfuscated JavaScript code (preload.js). Its main task is to copy all executable files from a local folder named temp to the user’s captures folder in the Videos folder. Afterward, it runs a signed application from that folder.
Source: Securelist
The team found several executables being used, such as Chrome and OBS Studio. The banker is loaded by sideloading a DLL dependency of these executables. In all cases, the libcef.dll library is used for DLL sideloading. Click here to readthe full report.
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