This rule is designed to detect potential abuse of the FlipHTML5 service, particularly focusing on messages that suggest the presence of an attachment but do not include one. It identifies communications containing phrases indicating that an attachment is part of the message, while the actual message body does not include any attachments. The rule further checks if any links present in the message lead to the FlipHTML5 domain (fliphtml5.com). Additionally, the rule leverages Natural Language Understanding (NLU) to assess the text for high-confidence patterns associated with credential theft. The combination of these factors aims to enhance detection capabilities against phishing attacks that utilize deceptive language and potential social engineering tactics to compromise user credentials.