Escalating Iranian Cyber Threats Target U.S. Defense and Critical Infrastructure

U.S. cybersecurity and intelligence agencies have jointly released an advisory alerting organizations to a growing wave of cyber threats originating from Iranian state-sponsored and affiliated actors. While the situation continues to evolve, the core message is unambiguous: entities operating within defense, operational technology (OT), and critical infrastructure must increase their security posture and adopt proactive measures. The advisory reinforces the enduring and adaptive nature of Iranian-linked cyber activity, particularly amid rising global tensions.

Iran-aligned threat actors are actively exploiting known vulnerabilities while also experimenting with new offensive strategies. Their targets often include defense contractors—especially those with connections to Israeli firms—and key sectors in the U.S. critical infrastructure landscape. Their preferred entry points remain familiar but no less dangerous: unpatched software, default or weak passwords, exposed internet-facing devices, and poorly segmented networks.

One of the chief challenges these actors capitalize on is the presence of legacy systems in OT and industrial control systems (ICS), which often lack modern security hardening and remain connected to the internet unnecessarily. Attackers frequently utilize reconnaissance tools like Shodan to scan for vulnerable devices, enabling them to conduct targeted campaigns that can escalate quickly once initial access is gained. Using a mix of remote access trojans (RATs), keyloggers, and legitimate administrative tools such as PsExec and Mimikatz, they navigate inside networks stealthily, bypassing many traditional endpoint defenses.

This threat landscape is compounded by the political context. Although government agencies have not confirmed a coordinated large-scale Iranian cyber campaign within the U.S. to date, the growing activity points to an escalation risk. In particular, hacktivists aligned with Iran continue to deploy ransomware, distributed denial-of-service (DDoS) attacks, and spear-phishing campaigns that target high-profile individuals, including journalists and cybersecurity experts. A recent example includes the APT35 group’s efforts to phish Israeli professionals using fake Google login and meeting invitations.

Addressing this multifaceted threat requires organizations to recognize that perfect security is unattainable. Instead, risk management and layered defense remain the most pragmatic strategy. The agencies recommend a focused approach emphasizing fundamental cybersecurity hygiene and OT-specific safeguards.

Key practical steps include disconnecting OT and ICS assets from the public internet wherever feasible. This simple measure drastically reduces the attack surface. Next, it is critical to replace default and weak passwords with strong, unique credentials and enforce multi-factor authentication (MFA), especially for OT network access. Incorporating phishing-resistant MFA methods can limit the success of credential theft attacks.

Timely patch management cannot be overstated. Ensuring that all software—whether in IT or OT environments—is up to date protects against exploitation of known vulnerabilities. Continuous monitoring of user access logs for remote OT connections helps detect anomalous activity early, enabling rapid incident response.

Organizations should also enforce strict protocols that prevent unauthorized changes or loss of control over OT systems. This can prevent attackers from disrupting critical infrastructure operations or exfiltrating sensitive data. Regular full-system and data backups remain essential to facilitate recovery in the event of ransomware or destructive attacks.

For those uncertain where to start, reviewing the external attack surface is a smart initial step. Tools provided by CISA’s Cyber Hygiene program or common open-source scanners like Nmap can identify exposed systems and outdated services. Aligning defenses with real-world threat tactics, such as those detailed in the MITRE ATT&CK framework, helps prioritize mitigation efforts based on the techniques employed by Iranian threat actors.

Despite the evolution of these cyber threats, Iranian adversaries still rely heavily on traditional attack paths—many of which can be effectively mitigated. The key is embracing a proactive, informed approach that combines basic cybersecurity practices with threat intelligence and operational awareness.

Heightened risk does not guarantee compromise. But it does demand resilience—achieved through disciplined security frameworks, early detection mechanisms, and strategic response capabilities.

In an era where geopolitical tensions spill into cyberspace, the strength of an organization’s defense lies in its ability to anticipate, adapt, and respond. Perfection may be out of reach—but strong, layered, and continuous protection is within grasp.