Microsoft is calling attention to a novel remote access trojan (RAT) named StilachiRAT that it said employs advanced techniques to sidestep detection and persist within target environments with an ultimate aim to steal sensitive data.
The malware contains capabilities to “steal information from the target system, such as credentials stored in the browser, digital wallet information, data stored in the clipboard, as well as system information,” the Microsoft Incident Response team said in an analysis.
The tech giant said it discovered StilachiRAT in November 2024, with its RAT features present in a DLL module named “WWStartupCtrl64.dll.” The malware has not been attributed to any specific threat actor or country.
It’s currently not clear how the malware is delivered to targets, but Microsoft noted that such trojans can be installed via various initial access routes, making it crucial for organizations to implement adequate security measures.
StilachiRAT is designed to gather extensive system information, including operating system (OS) details, hardware identifiers like BIOS serial numbers, camera presence, active Remote Desktop Protocol (RDP) sessions, and running graphical user interface (GUI) applications.
These details are collected through the Component Object Model (COM) Web-based Enterprise Management (WBEM) interfaces using WMI Query Language (WQL).
It’s also engineered to target a list of cryptocurrency wallet extensions installed within the Google Chrome web browser. The list encompasses Bitget Wallet, Trust Wallet, TronLink, MetaMask, TokenPocket, BNB Chain Wallet, OKX Wallet, Sui Wallet, Braavos – Starknet Wallet, Coinbase Wallet, Leap Cosmos Wallet, Manta Wallet, Keplr, Phantom, Compass Wallet for Sei, Math Wallet, Fractal Wallet, Station Wallet, ConfluxPortal, and Plug.
Furthermore, StilachiRAT extracts credentials stored in the Chrome browser, periodically collects clipboard content such as passwords and cryptocurrency wallets, monitors RDP sessions by capturing foreground window information, and establishes contact with a remote server to exfiltrate the harvested data.
The command-and-control (C2) server communications are two-way, allowing the malware to launch instructions sent by it. The features point to a versatile tool for both espionage and system manipulation. As many as 10 different commands are supported –
- 07 – Display a dialog box with rendered HTML contents from a supplied URL
- 08 – Clear event log entries
- 09 – Enable system shutdown using an undocumented Windows API (“ntdll.dll!NtShutdownSystem”)
- 13 – Receive a network address from the C2 server and establish a new outbound connection.
- 14 – Accept an incoming network connection on the supplied TCP port
- 15 – Terminate open network connections
- 16 – Launch a specified application
- 19 – Enumerate all open windows of the current desktop to search for a requested title bar text
- 26 – Put the system into either a suspended (sleep) state or hibernation
- 30 – Steal Google Chrome passwords
“StilachiRAT displays anti-forensic behavior by clearing event logs and checking certain system conditions to evade detection,” Microsoft said. “This includes looping checks for analysis tools and sandbox timers that prevent its full activation in virtual environments commonly used for malware analysis.”
The disclosure comes as Palo Alto Networks Unit 42 detailed three unusual malware samples that it detected last year, counting a passive Internet Information Services (IIS) backdoor developed in C++/CLI, a bootkit that uses an unsecured kernel driver to install a GRUB 2 bootloader, and a Windows implant of a cross-platform post-exploitation framework developed in C++ called ProjectGeass.
The IIS backdoor is equipped to parse certain incoming HTTP requests containing a predefined header and execute the commands within them, granting it the ability to run commands, get system metadata, create new processes, execute PowerShell code, and inject shellcode into a running or new process.
The bootkit, on the other hand, is a 64-bit DLL that installs a GRUB 2 bootloader disk image by means of a legitimately signed kernel driver named ampa.sys. It’s assessed to be a proof-of-concept (PoC) created by unknown parties from the University of Mississippi.
“When rebooted, the GRUB 2 bootloader shows an image and periodically plays Dixie through the PC speaker. This behavior could indicate that the malware is an offensive prank,” Unit 42 researcher Dominik Reichel said. “Notably, patching a system with this customized GRUB 2 bootloader image of the malware only works on certain disk configurations.”
