This detection rule focuses on identifying malicious HTML attachments that exhibit excessive padding and suspicious patterns indicative of potential phishing or malware distribution attempts. The rule triggers when an inbound attachment meets specific criteria, including being of type HTML or possessing certain file extensions associated with HTML documents. It further inspects the content of the file for excessive line breaks and utilizes YARA scans to find matches against defined malicious patterns, particularly associated with HTML structure abuse. The detection is crucial as attackers often employ tactics such as HTML smuggling and evasion techniques to bypass security measures, making it imperative for cybersecurity systems to flag these potentially harmful attachments.