Phishing Campaign Sends Millions of Emails Using Invisible Unicode to Evade Filters
Microsoft is alerting of a "high-volume phishing campaign" that's using invisible Unicode tag characters to bypass email filters. "Instead of using these characters to hide instructions from people while exposing them to AI models, the attacker used them to split financial lure words such as 'funding' to prevent email filters from parsing them," the Microsoft Security Research team said . The Windows maker said the findings show AI-era evasion techniques can be adapted by threat actors in traditional phishing and spam campaigns. Attacks exploiting this approach are said to have first emerged in early February 2026. ASCII Smuggling refers to a technique where invisible or non-rendering Unicode characters are used to conceal messages or instructions inside seemingly-harmless text. As a result, human user interfaces do not render them, making the text appear completely normal to the user. However, such content can be ingested by email filters or AI...
Sep 04, 2026
