CISA tells operators to harden Siemens S7 PLCs. Here’s how to do it without disrupting production
CISA, NSA, FBI and other agencies warn of active targeting of internet-exposed Siemens S7 PLCs and urge patching, exposure removal and hardening.
Joint advisory AA26-231A from the NSA, CISA, FBI, Department of Energy and EPA warns that actors are actively targeting Siemens S7 PLCs using internet scanning, AI-assisted scripts and libraries such as Snap7 and python-snap7 over S7comm on TCP port 102. The advisory covers S7-200 through S7-1500 series controllers and recommends patching, removing internet exposure, access controls, monitoring and disabling unneeded services. Siemens states no new S7 vulnerabilities are involved, only misconfigurations addressed in existing ProductCERT guidance SSB-104599. The article details how to apply each measure without breaking production dependencies such as remote I/O, HMI links and diagnostics.
NSA, CISA, FBI, DOE, and EPA Warn of Active AI
Five US agencies warn of active AI-assisted attacks on internet-exposed Siemens S7 PLCs across critical infrastructure, using disguised snap7 scripts for pre-positioning reconnaissance.
NSA, CISA, FBI, DOE, and EPA issued joint advisory CISA AA26-231A warning of an active hacking campaign against Siemens S7-series PLCs, from S7-200 through S7-1500 F-series, across US critical infrastructure. Threat actors use internet scanning services such as Censys and ZoomEye to locate exposed controllers, then perform read operations over S7comm on TCP port 102 using the legitimate snap7.dll and python-snap7 libraries, disguising AI-generated exploitation scripts as monitoring tools. The agencies assess the activity as pre-positioning ahead of possible process disruption, equipment damage, or safety incidents in Energy, Water, Critical Manufacturing, Chemical, Food and Agriculture, and Commercial Facilities sectors.