Seasoning email threats with hidden text salting
Introduction to hidden text salting
Hidden text salting (or "poisoning") is an effective technique employed by threat actors to craft emails that can evade parsers, confuse spam filters, and bypass detection systems that rely on keywords. In this approach, features of the Hypertext Markup Language (HTML) and Cascading Style Sheets (CSS) are used to include comments and irrelevant content that are not visible to the victim when the email is rendered in an email client but can impact the efficacy of parsers and detection engines. Due to the simplicity of hidden text salting and the number of ways threat actors can insert gibberish content in emails, this approach can introduce significant challenges to email parsers, spam filters, and detection engines.
