Gootloader, a JavaScript-based malware loader, has resurfaced with renewed activity after a brief hiatus. This malware is primarily used by the threat actor known as Storm-0494 to gain initial access, often leveraging SEO poisoning to attract users to compromised sites. Gootloader employs heavily obfuscated JavaScript to deliver additional payloads and is known for facilitating infections that lead to the deployment of various ransomware families, such as Rhysida, BlackCat, Zeppelin, and Quantum Locker through another actor, Vanilla Tempest.
One of the novel techniques used in recent Gootloader operations includes the incorporation of custom WOFF2 fonts, which employ glyph substitution to obscure filenames. The loader exploits WordPress comment submission endpoints to deliver XOR-encrypted ZIP files containing payloads, with a unique decryption key hardcoded in the site’s source code.