AI spam filters are getting suckered by old-school text salting

Summary

security AI spam filters are getting suckered by old-school text salting Turns out decades-old email tricks still work against some LLM-powered email filters Notice more spam getting through that corporate email filter lately? Attackers are using a technique known as "text salting," which hides benign-looking words intended to confuse some AI-powered email filters, says cybersecurity firm Barracuda.The email security outfit said on Thursday that it had detected more than one million retail-themed phishing attacks using text salting since April. It’s not a new technique by any stretch and has been used to fool traditional secure email gateways for years, but Barracuda says it can also confuse machine-learning and LLM-based security tools.Text salting involves peppering (sorry) a malicious email with random, harmless-seeming words in order to fool an email scanning system into thinking there’s nothing off about the flavor of a message (sorry again), tricking the system into passing it to its recipient for consumption (I’ll stop with the food jokes here). Pour a pile of salty text on top of an email and a human reader would probably get suspicious, however, so attackers typically use one or more of three flavor variations (okay, I'm done – promise) to hide the additives from human readers, but not automated scanners, per Barracuda. Typical techniques include CSS cropping, which sets the visible window small enough that a human won't see the hidden filler text; text manipulation to move the salty copy outside the visible screen; and zero font techniques which insert misleading words between suspicious phishing copy that’s visible to a machine but not a human. The end result of each of those techniques is a message that reads less malicious, more gibberish to a machine, leading it to assume the email is fine, and which looks exactly as the attacker intended when viewed by a human. Modern email security systems have largely adapted to these techniques, with newer tools ab...