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Getting Active The Right Way (In OT Security): Going Beyond the Passive Approach

August 25, 2023

When it comes to OT security we don’t have to look too far back to see significant moments of progression of cyber threats and cybersecurity initiatives. It’s a space making progress in a relatively short period of time, yet many industrial operators remain in relatively early stages of cybersecurity maturity. We often hear that OT security leaders remain in a mode of "catch-up," not only to evolving threats but also in terms implementing security that are considered best practices in IT but require a modified approach in operational environments.

OT is on an ongoing journey in understanding how to implement security controls that support the availability, and even more importantly, safety, of operating environments. Think back to the beginning of “air-gapping” OT from IT environments, where the concept of using a firewall was a completely new thing for operational environment. then experimenting with various basic scanning methods to understand and monitor these environments, build asset inventory and identify vulnerabilities. We faced a few hiccups (read: disruptive scans) along the way, which propelled the industry towards a stronger emphasis on passive monitoring at the network level. Now, we find ourselves at another defining juncture, where there's a growing realization of the need for a more integrated approach. An approach that dives deeper into asset data, yet remains operationally safe for ICS environments.

OT is on an ongoing journey to understand how to implement security controls that support the availability, and even more importantly, the safety of operating environments. Think back to the beginning of “air-gapping” OT from IT environments. At that time, the concept of using a firewall was entirely new for operational environments. We then began experimenting with basic IT scanning methods to understand and monitor these environments, build an asset inventory, and identify vulnerabilities. We faced a few hiccups (read: disruptive scans knocking over OT devices) along the way, which propelled the industry towards a stronger emphasis on passive monitoring at the network level. Now, after a period of "passive only," we find ourselves at another defining juncture: the need for more complete, accurate OT asset information via an integrated data collection approach that goes beyond passive monitoring. Whereas "active" was once taboo in OT, security teams are now implementing active methods in intelligent ways, using an integrated approach that delves deeper into asset data while remaining operationally safe for ICS environments.


The Passive Approach: A Reaction to Disruption

With the realization that traditional IT security measures could disrupt OT assets, the industry started looking for alternatives. Passive monitoring emerged as a solution. This approach involves monitoring network traffic without actively interacting with the devices on the network. By using network taps and spans, organizations could gain insight into the traffic on their networks without the risk of disrupting their OT assets.

Passive monitoring provides a good understanding of network activities. It can recognize and fingerprint some of the traffic and provide a basic understanding of assets in an environment. However, its limitations in OT asset management are evident. Passive methods can't differentiate between certain devices based on network traffic alone, such as distinguishing between a Windows 7 and a Windows 10 system. And without directly interacting with devices, it's impossible to get a comprehensive view of software, firmware, and other crucial details.


The Need for an Integrated Approach that Includes Active

While passive monitoring was a step in the right direction, relying solely on it leaves many unknowns about the state of security and compliance of OT assets. It's not just about identifying potential external threats but understanding internal configurations, vulnerabilities, and assets to mitigate risks.

While early experiments in active methods caused some fear, technology, tools and expertise has evolved in the OT arena. Again, as OT security strategies continue to mature, operators have validated OT specific, active data collection methodologies that keep operations at the forefront, versus trying to make IT products work in OT. These refined approaches are now recognized as both safe and effective for OT environments, ensuring optimal operational security. Active methods can gather details that passive monitoring can't, like the specific applications on a device, its firmware version, open ports, and more — data that is the bedrock of any security and compliance program.

Yet, it's crucial to understand that the security conversation shouldn't focus on choosing between active and passive methods. Rather, the emphasis should be on integrating both for a comprehensive view. This fusion approach provides a broader perspective from passive monitoring, complemented by the in-depth insights active monitoring offers.

As OT environments grow more integrated with IT systems, the demand for robust, nuanced security solutions escalates. It's clear that relying on a single method of monitoring or a single line of defense is insufficient. Much like the inadequacy of firewalls as the sole protector, neither passive nor active monitoring alone can offer complete security. The future of OT security demands a holistic, integrated strategy, combining the strengths of both monitoring methods to safeguard and streamline critical operations.


How Industrial Defender Can Help

Industrial Defender understands these unique challenges. We take an integrated data collection approach, tailored to your specific environment, ensuring the safest and most effective method to gain profound insights into your OT sphere. Our strategy isn't about choosing one method over the other; it's about harnessing them in unity to deliver unparalleled clarity and security.

Using this integrated method, Industrial Defender delivers the most thorough OT asset data. By employing a balanced mix of:

  • Manual data ingestion
  • Passive and active data collection
  • Both agent-based and agentless techniques

Read our Data Collection solution brief to learn more.