Vishing campaign abuses Microsoft Teams to give attackers a foothold in company networks
Unit 42 details 'Spring Ring', a vishing campaign using fake IT support on Microsoft Teams to reach 150+ employees at 10+ companies.
Palo Alto Networks Unit 42 documented 'Spring Ring', a voice-phishing campaign that ran January to April 2026, using 26 attacker identities and fake Microsoft 365 tenants such as 'ITProtectionDepartment' to impersonate internal IT support on Microsoft Teams. One path used Quick Assist or downloaded remote-support tools to run an obfuscated PowerShell script that disabled malware scanning before contacting C2; the other delivered a cloud-hosted file triggering browser hijacking, SMB internal network scanning, and a PetitPotam NTLM relay attempt against domain controllers to gain domain-level privileges. Both intrusion attempts were blocked before attackers reached their objectives. Collaboration-platform phishing alerts rose to 42% of Unit 42's telemetry in early 2026, up from 30%.
ASCII smuggling crosses over from AI prompt injection to phishing evasion
Microsoft details high-volume phishing campaign using ASCII smuggling (Unicode tag chars) for filter evasion, peaking at 2.3M messages.
Microsoft researchers observed a high-volume finance-themed phishing campaign using invisible Unicode tag characters (U+E0000–U+E007F), a technique known from AI prompt injection research as ASCII smuggling, to split lure words like 'funding' and evade email filters. Telemetry from Microsoft Defender for Office 365 showed signature hits jump from roughly 21,000 messages on February 8, 2026 to more than 1.3 million on February 9, peaking above 2.3 million on February 11, with elevated weekday activity lasting approximately three months. The discovery emerged from prompt injection protection research, showing AI-era evasion techniques crossing into traditional phishing. Most messages were flagged by layered Defender protections rather than a single Unicode-specific signal.