FormBook Malware Uses Phishing, DLL Side-Loading, JavaScript
Source AlienVault OTX General
Description
Two distinct phishing campaigns have been identified targeting companies in Greece, Spain, Slovenia, Bosnia and Central American countries to deliver FormBook data-stealing malware. The first campaign uses RAR attachments containing legitimate executables like Sandboxie ImBox.exe, TikTok desktop, Adobe PDF Preview Handler, and XZ Utils, exploiting DLL side-loading with malicious DLL files. The second campaign deploys heavily obfuscated JavaScript that drops encrypted PNG files, uses PowerShell with Base64 encoding, and leverages a custom .NET loader called Mandark to inject the payload into RegAsm process. Both campaigns deliver the same FormBook executable that employs advanced evasion by manually mapping ntdll.dll in memory to bypass user-mode monitoring and perform direct syscalls, enabling credential theft and data collection from browsers while avoiding detection mechanisms.