Operation Oxidovy, Threat Actors Targeting Government And Military Officials

The recent campaign targeting the Czech Republic involves a malicious ZIP file that contains a decoy LNK file and a batch script.

The LNK runs the batch script, which spawns a decoy PDF document and renames a masqueraded PDF file to a portable executable, which is copied to the startup folder for persistence. 

Decoy documents are likely used to lure the target into opening the malicious file, and the entire malware ecosystem, including HavocC2 and Freeze, is involved in this campaign.

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The two decoy documents analyzed are “Password Change from the Internal Network of the Ministry of Defense (IMO)” and “The importance of and outlook for the Czech Republic in NATO.”

The first document instructs users to change their passwords by navigating to a specific URL and adhering to password complexity guidelines. 

The second document discusses the importance of relations between the Czech Republic and NATO, including geopolitical advantages and current security issues. 

The first decoy document is irrelevant to the initial ZIP file name, while the second document is thematically relevant, which suggests that the attacker may be using a watering hole attack, targeting users interested in Czech Republic-NATO relations.

A ZIP file contains a malicious LNK file that spawns a malicious batch script, which changes the attributes of decoy documents and renames a masqueraded PDF to “AdobeReader.exe,” copying it to the Startup folder for execution.

The script also hides and protects the LNK file and payload from unauthorized modification or deletion. 

Rust-based loader known as Freeze is then executed, which uses ETW patching to bypass EDRs, unhooks DLLs, repatches ETW, and decodes and decrypts shellcode, which is a malicious Havoc DLL that contains subroutines for loading modules, retrieving functions, and facilitating payload activities.

The extracted configuration specifies the execution path for both 32-bit and 64-bit architectures, the HTTP method for communication, and the Command and Control server address. 

The DemonConfig function parses this configuration from the .data section for further use and generates unique metadata for the payload, including identifying information and system details. 

It establishes a connection to the Command and Control server, decrypts received data using AES encryption, processes tasks using the CommandDispatcher, and employs sleep obfuscation techniques to avoid detection.

Seqrite identified a targeted attack against the Czech military likely originating from Russia, where the attackers used a custom Rust-based loader (AdobeReader.exe) with a unique PDB path to deploy a Havoc Demon shellcode (demon.x64.dll). 

Further analysis revealed another loader (gnobya.exe) from May 2024 that downloaded a Sliver Stager.

Both loaders used open-source tools and targeted the Czech Republic, while the C2 servers were located in the Netherlands and Bulgaria. 

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