ASCII smuggling crossed from prompt injection into a 2.3-million-message-a-day phishing campaign.

Microsoft published a teardown on September 3 of a campaign abusing the Unicode Tags block (U+E0000-U+E007F), specifically TAG SPACE U+E0020, to split financial keywords so literal signatures miss them and ML tokenizers stop seeing familiar units. Volume went from about 21,000 messages to over 1.3 million on February 9, peaked at 2.3 million on February 11, ran weekdays-only for about three months, and stopped after May 15, across roughly 150 finance-themed sender domains routed through ActiveCampaign for authentication reputation. Microsoft's guidance for anyone piping email into an assistant: strip or normalize the tag block from subject and body before applying content signatures and before AI ingestion, and treat its presence as an anomaly signal (Microsoft Security).