Unauthorized actors are actively targeting internet-facing automatic tank gauge (ATG) systems in the United States, prompting federal agencies to urge site owners to take immediate remediation steps.
ATGs are electronic sensors utilized by industrial sites to monitor liquid storage tanks, tracking everything from dangerous chemicals to standard fuel reserves. In a network architecture, these devices are relatively straightforward: they consist of probes that feed data to displays, which in turn supply readings to broader supervisory control and data acquisition (SCADA) systems. This allows plant operators to monitor environmental conditions remotely. While ATGs may not always be the primary focus of an organization's security posture, they represent a significant operational risk equivalent to other critical equipment in an industrial facility.
This week, a coalition of federal agencies—including the Cybersecurity and Infrastructure Security Agency (CISA), Federal Bureau of Investigation (FBI), National Security Agency (NSA), Department of Energy (DoE), Environmental Protection Agency (EPA), Transportation Security Administration (TSA), Department of Transportation (DOT), and US Department of Agriculture (USDA)—published a joint notice advising industrial organizations to harden their ATGs against unauthorized access.
The agencies stated they are aware of malicious cyber activity targeting these systems in the US. While the activity was not attributed to a specific threat actor group, the statement aligns with reports including last month detailing that actors loosely linked and Iran have been targeting ATGs at gas stations across the country.
The notice detailed how, by taking advantage of vulnerabilities in ATGs, unauthorized parties could alter tank readings, pump controls, and safety settings. If plant operators remain unaware of the unauthorized access, particularly concerning safety-critical systems, the resulting hazardous conditions could cause significant physical and environmental damage. ATGs also manage critical alerting functions, notifying operators of abnormal conditions within a tank. Disabling these alerts actively degrades a facility's safety margins.
Exposure Data Indicates Concentration in the US
Data indicates that the majority of exposed ATGs are currently located in the United States. Following the joint notice, The Shadowserver Foundation conducted widespread scans to identify ATGs exposed to the open web.
After filtering out discoverable devices acting as honeypots, the data showed that the vast majority of under-protected ATGs in production environments were concentrated in a single country. As of the time of publication, there were 909 discoverable devices in the US. The next highest exposures were found in Canada (30 devices), Australia (22), the UK (four), and Brazil (four).
While the US constitutes the overwhelming majority of vulnerable ATGs globally, the current figure of 909 active instances represents a substantial, measurable improvement in stateside infrastructure security. A decade ago, reporting by Dark Reading identified nearly 6,000 ATGs exposed to the public internet across the nation.
Legacy Operational Technology and Security Risks
Like many industrial control systems, ATGs prioritize reliability and continuous uptime over native security controls. They are designed to operate in the field for years without downtime, which often leaves them running legacy software stacks that are rarely updated. Furthermore, their hardware constraints generally prevent the installation of modern endpoint protection software.
Given these constraints, it is unsurprising that researchers consistently identify significant vulnerabilities within these systems. In a recent security evaluation, researchers at Bitsight identified seven critical zero-day vulnerabilities across six of the most widely used ATG models. These findings included command-injection vulnerabilities carrying maximum CVSS scores of 10.0, alongside authentication bypass issues and hardcoded credentials.
If an advanced persistent threat (APT) actor accesses an ATG over the open internet, they could abuse the system to gather operational intelligence, supporting follow-on network movement. An equally pressing risk involves threat actors intentionally cutting industrial operators off from the data they rely on, blinding them to the physical realities of their critical systems.
Recommended Actions for Securing ATG Infrastructure
The primary mitigation step recommended by US federal agencies is to disconnect all ATGs from the public internet.
Andrew Ginter, vice president of industrial security at Waterfall Security Solutions, notes the evolving understanding of industrial network defense: "Years ago, I thought the first thing to do to launch an operational technology (OT) security program was segmentation. A firewall or three. I was recently corrected: the first step is to get your devices and human machine interfaces (HMIs) off the Internet. Do it on an emergency basis."
If an organizational requirement dictates that an ATG must maintain internet connectivity, Ginter recommends implementing comprehensive hardening measures: "Auto update. Long passwords. Encrypt everything. If you can't do that either, you have intrinsically bad design."
To further secure these environments, US authorities advise enforcing credential security and applying patches—a step that requires careful planning in always-on industrial sites where downtime must be scheduled. Organizations must also actively monitor their networks for unauthorized access and unusual traffic patterns.
At a structural level, organizations can protect themselves against worst-case scenarios by implementing cyber-informed engineering (CIE). Ginter points out that operators can deploy CIE-style analog controls and highly resilient digital mitigations to preempt unacceptable physical consequences. Practical examples include installing over-pressure release valves and float valves that mechanically prevent dangerous tank conditions, as well as implementing unidirectional gateways to ensure unauthorized network traffic cannot reach vulnerable OT equipment.