Traditional Email Security Is Falling Behind as Attackers Shift Tactics

Phishing gateways and signature-based email filters — the tools most companies have relied on for years — are increasingly failing to catch the attacks that matter most. Security researchers point to a clear shift: instead of obviously malicious attachments or links, attackers are now leaning on trust itself.

Business email compromise and account takeover attacks have moved toward impersonating coworkers, vendors, or partners, then abusing legitimate authentication flows to slip past defenses. One technique gaining traction is Device Code phishing, which tricks users into authorizing a malicious login through a real, legitimate authentication process — meaning there's no suspicious link or file for traditional filters to flag at all.

The practical fallout for security teams is real: because these attacks look legitimate on the surface, analysts end up manually digging through flagged emails just to determine whether something is a genuine compromise or a false alarm. That's slow, resource-heavy, and doesn't scale as attack volume grows.

The industry's answer increasingly points toward behavioral AI — systems that watch for anomalies in communication patterns and account behavior rather than matching against known-bad signatures. Instead of asking "does this email contain a known malicious link," these tools ask "does this behavior look normal for this person or account" — catching compromises that never trip a traditional filter.