Description

Cybercriminals are using a signed Logitech installer to distribute a new Brazilian banking trojan known as TCLBANKER. The malware mainly targets users in Brazil and monitors dozens of banking, fintech, and cryptocurrency websites. Once victims access these sites, the trojan activates and communicates with a remote command-and-control server, allowing attackers to control sessions and steal sensitive financial information in real time. The infection begins with a malicious ZIP archive containing an MSI installer that abuses the legitimate Logitech AI Prompt Builder application. Researchers identified the malware as an advanced evolution of older banking trojans such as MAVERICK and SORVEPOTEL. TCLBANKER uses DLL sideloading to load a malicious DLL through a trusted Logitech process, helping it bypass security checks and reduce user suspicion. The malware also contains anti-debugging and anti-sandboxing techniques to avoid detection during analysis. To remain hidden, the trojan modifies system processes, disables telemetry monitoring, and decrypts its payload only when specific environment conditions are met, including Brazilian language and locale settings. If a system appears to be a sandbox or analysis environment, the malware stops execution. Once active, it monitors browser activity and collects system information before establishing communication with its command server. TCLBANKER also deploys phishing overlays that imitate banking pages and Windows update screens to trick victims into providing credentials. Additional modules allow the malware to spread through WhatsApp and Outlook by sending malicious messages and phishing emails to contacts. Security teams should monitor suspicious signed installers, restrict DLL sideloading, and block connections to known malicious domains to reduce exposure.