Cybersecurity researchers have identified a novel malware campaign that utilizes Google Sheets as a command-and-control (C2) mechanism. Detected by Proofpoint starting August 5, 2024, this campaign impersonates tax authorities from various countries, including the United States, the United Kingdom, France, Germany, Italy, India, and Japan. The primary objective is to target over 70 organizations across multiple sectors, such as insurance, aerospace, healthcare, finance, and government. The bespoke tool employed in this campaign, dubbed Voldemort, is capable of gathering sensitive information and delivering additional malicious payloads.
The cyber espionage campaign has been extensive, with as many as 20,000 email messages sent to potential victims. These emails typically claim to be from tax authorities and notify recipients of changes to their tax filings. The emails encourage users to click on Google AMP Cache URLs, which redirect them to an intermediate landing page designed to inspect the User-Agent string. If the operating system is identified as Windows, a Windows shortcut file is displayed, masquerading as a PDF document, tricking users into executing it.
Once executed, the LNK file triggers PowerShell to run a Python script sourced from a WebDAV share. This Python script gathers system information and sends the data as a Base64-encoded string to a domain controlled by the threat actors. After the data exfiltration, the user is presented with a decoy PDF while a password-protected ZIP file is downloaded. This ZIP file contains a legitimate executable that is vulnerable to DLL side-loading and a malicious DLL file, known as Voldemort, which serves as a custom backdoor with capabilities for information gathering and loading additional payloads.
The unusual nature of this campaign raises questions about the threat actors’ objectives and capabilities. Researchers noted that while many characteristics align with cybercriminal activities, the espionage aspect remains unclear. This amalgamation of sophisticated and basic techniques makes it challenging to accurately assess the threat actor’s level of expertise. The findings suggest that the attackers may be casting a wide net before narrowing down their targets, indicating a calculated approach to achieve their unknown goals.
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