ASCII smuggling crosses over from AI prompt injection to phishing evasion

Attackers are exploiting invisible Unicode tag characters to split financial lure keywords in phishing emails, bypassing traditional email content filters that cannot parse these hidden characters. This technique, originally developed in AI prompt injection research, demonstrates how offensive methods rapidly migrate from one threat domain to another — in this case from AI jailbreaking to conventional phishing campaigns. The core failure is that email security tooling was not designed to account for non-rendering Unicode characters as a text obfuscation vector. This matters because organizations relying solely on keyword-based filtering are now blind to a growing category of evasion techniques, leaving employees exposed to convincing financial-themed lures. The sharp increase in detections by Microsoft Defender for Office 365 signals this is an active, scaling threat requiring immediate defensive adaptation.