Description

With Tax Day approaching on April 15, Seqrite Labs discovered a grim threat to cybersecurity affecting U.S. citizens in the form of an advanced phishing attack. Tax season is being exploited by cyber-fraudsters using spoofed emails with malicious files that attempt to steal individual and financial information. The malware attackers mainly engage in social engineering tactics and malevolent LNK files masquerading as real tax forms, in order to trick recipients into launching malicious payloads. Vulnerable groups such as green card holders, small business people, and recently entrant taxpayers are especially vulnerable with limited experience with tax procedures. The attack starts with phishing emails containing Base64-encoded PowerShell scripts. When run, they download additional malware files like "rev_pf2_yas.txt" and "revolaomt.rar" from attacker-controlled servers. The last payload, also referred to as "Setup.exe" or "revolaomt.exe," is a PyInstaller-bundled Python executable. It decrypts and loads Stealerium, a.NET-based info stealer (version 1.0.35), famous for stealing sensitive information from browsers, cryptocurrency wallets, and messaging apps like Discord and Telegram. Stealerium performs in-depth system discovery—scanning Wi-Fi data, webcam images, and even adult content for focused monitoring. Its advanced evasion techniques, including sandbox detection and mutex management, complicate traditional security software to detect. The malware uses concealed folders in %LOCALAPPDATA% for persistence and transfers pilfered data to Command and Control (C2) servers like using AES-256 encryption for secure exfiltration. Apart from credential stealing, the malware is also focusing on gaming platforms, email clients such as Outlook, and VPN. Seqrite Labs suggests proper endpoint protection by the users along with a constant watch for spam emails and attachments during tax season. This will avoid identity theft and financial loss.