Siemens S7-1200

Iranian Hackers Disable Safety Alarms in US Industrial Control Systems

Iranian threat actors have been compromising internet-exposed industrial controllers across the United States since at least March 2026, modifying alarm and safety shutdown logic in critical infrastructure. The campaign has targeted government organizations and operators in the water, wastewater, and energy sectors, resulting in operational disruptions and financial losses. Attackers focus on devices with insecure remote access, weak credentials, or default configurations rather than exploiting zero-day vulnerabilities. Targeted hardware includes Rockwell CompactLogix and Micro850 controllers, Schneider BMX P34 and Modicon M340 PLCs, and Siemens S7-1200 models. Operators use rented foreign infrastructure and legitimate programming software to download, alter, and re-upload control logic projects. In at least one case, malicious code maintained normal operations while introducing instructions that bypassed safe operational limits and altered data displayed on HMI and SCADA interfaces. The tactics closely resemble prior activity attributed to the CyberAv3ngers group linked to Iran’s Islamic Revolutionary Guard Corps, though direct attribution remains unconfirmed.