Spammers Adopt ASCII Smuggling Technique Using Invisible Unicode Characters

A Unicode character block that is invisible to human readers is seeing growing adoption among spammers and malicious actors. The technique, known as ASCII smuggling, was previously associated with attacks targeting AI systems. The characters cannot be seen by users but can be interpreted by software, making them useful for hiding malicious content. What was once a niche method used against AI models is now being embraced more broadly in spam campaigns. The shift signals an evolution in how threat actors are exploiting overlooked text-encoding vulnerabilities.