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CISA Flags Palo Alto PAN-OS Zero-Day as Actively Exploited, Orders Federal Fixes by May 9

The bug in the User-ID Authentication Portal lets remote attackers run code as root on PA- and VM-Series firewalls.

Overview

  • CISA, which added the flaw to its Known Exploited Vulnerabilities catalog Wednesday, gave federal agencies until May 9 to secure exposed devices.
  • Palo Alto says exploitation remains limited and targets portals reachable from the internet, with Unit 42 tracking the activity as cluster CL-STA-1132 tied to suspected state-sponsored tradecraft.
  • Vendor telemetry shows attempts starting April 9 progressed to remote code execution a week later through shellcode injected into an nginx worker on a firewall.
  • After access, the intruders cleared crash logs, enumerated Active Directory with the firewall’s service account, and dropped EarthWorm and ReverseSocks5 to tunnel traffic.
  • Fixes begin May 13 with more on May 28, and admins should restrict or disable the portal, as internet scans still find thousands of PAN-OS instances exposed.