Description

TA558, a notorious hacking group active since 2018, has launched a sophisticated campaign dubbed "SteganoAmor," leveraging steganography to conceal malicious code within images. This technique, aimed at evading detection by users and security products, delivers various malware tools onto targeted systems. Positive Technologies uncovered this campaign, identifying over 320 attacks across different sectors and countries, with a focus on Latin America. The attack begins with malicious emails containing seemingly innocuous document attachments exploiting the CVE-2017-11882 flaw in Microsoft Office Equation Editor. These emails, sent from compromised SMTP servers to appear legitimate, download a Visual Basic Script (VBS) from a legitimate service upon opening. The script then retrieves an image file (JPG) containing a base-64 encoded payload. Subsequently, PowerShell code within the script downloads the final payload hidden inside a text file, encoded in reverse base64. Positive Technologies observed various malware families delivered through this attack chain, including AgentTesla, FormBook, Remcos, LokiBot, Guloader, Snake Keylogger, and XWorm. These malware types steal sensitive information, capture keystrokes, take screenshots, and enable remote control of compromised machines. Compromised legitimate FTP servers serve as command and control (C2) infrastructure, disguising traffic to appear normal. While most attacks target Latin American countries, the campaign's scope extends worldwide. Updating Microsoft Office to a recent version can mitigate this threat effectively, as it renders the seven-year-old vulnerability exploited by TA558 obsolete. Vigilance and timely updates remain crucial defenses against evolving cyber threats.