East-West Cyberattacks and How They Work

By Asimily Editorial TeamPublished August 11, 2026

In the contemporary digital enterprise, the perimeter has effectively dissolved. For decades, network security was defined by the “castle and moat” mentality, where rigorous defenses at the network edge were sufficient to protect internal assets.

However, the rise of cloud-native architectures, microservices, and distributed workloads has fundamentally shifted this paradigm. Today, the vast majority of network traffic occurs internally between servers, applications, and services on an internal network. The rise of Internet of Things (IoT), operational technology (OT), and Internet of Medical Things (IoMT) devices only increases internal network communication traffic and complexity. This internal data flow is what network architects and security professionals refer to as east-west traffic. For reference, north-south traffic typically involves the open internet or clients outside of a protected network.

By understanding east-west traffic and its unique challenges, organizations can implement security best practices that mitigate cybersecurity risks.

What Is East-West Traffic?

East-west traffic is the data exchanged between internal systems – like servers, apps, and connected devices – within a network, rather than moving in and out of the network perimeter. This internal traffic encompasses various communications between assets. Below is a diagram illustrating the key differences between east-west and north-south traffic.

What Are Some Examples of East-West Traffic?

Understanding east-west traffic requires looking beyond basic network connectivity. It manifests in various forms, ranging from essential business-logic communications to routine administrative overhead. Some examples include:

Database replication between edge IoT gateways and centralized OT historians: Industrial sensors often feed local edge databases first, which then replicate that data to a central historian database for long-term storage and analysis, creating internal traffic between two database instances rather than a single write path.
Firmware and configuration updates pushed between IoT device fleets: When a smart building system rolls out an update to hundreds of connected thermostats or badge readers, that update often propagates device-to-device or through a local gateway rather than pulling directly from the internet, creating easily overlooked internal traffic that attackers can use for spreading malicious payloads.
IoMT device data syncing through an application server before reaching clinical systems: Rather than writing directly to hospital records, many connected medical devices send readings to an intermediary application server, which validates and formats the data before passing it along, adding another internal hop to the east-west path.

What Is The Difference Between North-South Traffic And East-West Traffic?

When looking at north-south and east-west traffic, the differences fall into a few categories:

Direction of flow: While north-south traffic moves between the internal network and external sources, east-west traffic moves laterally between systems inside the same network or data center.
Security focus and tooling: While organizations traditionally secure north-south traffic with perimeter defenses like firewalls, Intrusion Detection Systems (IDS), Intrusion Prevention Systems (IPS), and gateways, they secure east-west traffic with internal controls like segmentation, microsegmentation, and zero trust policies.
Visibility: While north-south traffic monitoring is easier because it passes through a limited number of locations, east-west traffic is harder to manage since it can move across many internal paths without ever hitting a central inspection point.

How Do Malicious Actors Leverage East-West Traffic During An Attack?

Once an attacker gains initial unauthorized access, the real damage often occurs as the malicious actor abuses east-west traffic. Since organizations often struggle to monitor and manage internal network communications, attackers can evade detection more easily.

Some different ways attackers use east-west traffic to evade detection include:

Initial access and reconnaissance: Mapping out systems and identifying vulnerabilities like misconfigured permissions, unpatched systems, or poorly secured IoT devices.
Lateral movement: Hopping across systems, often using legitimate credentials and protocols.
Privilege escalation: Seeking more access and generating more east-west traffic as they test what they can reach.
Persistence and data exfiltration. Building backdoors to maintain access, then staging their move toward their goal internally, like stealing data, disrupting operations, or deploying ransomware.

What Are Some East-West Network Security Challenges?

Securing east-west traffic is fundamentally harder than securing the perimeter, and that difficulty compounds in environments that have large IoT, OT, and IoMT device fleets.

Lack of Visibility

Traditional security tools are built to inspect traffic crossing a barrier from the public internet, like a firewall at the network edge. East-west traffic moves across countless internal paths with no single point where all of it can be seen or inspected.

Encrypted Traffic Blind Spots

Even when organizations monitor east-west traffic, security teams struggle since encryption makes it difficult to identify:

The data being transferred.
The application or protocol generating traffic.
A connection’s legitimacy or maliciousness.
Communications from compromised devices.

Flat Network Architecture

Many internal networks still lack segmentation. If an attacker gains control of an IoT or OT device, they can move further into the network than they should, turning a single compromised system into a launchpad for lateral movement.

Scale and Complexity

Cloud, hybrid, and multi-site environments generate large volumes of east-west traffic across constantly shifting infrastructure. This makes it difficult to maintain consistent policies or keep pace with what “normal” traffic even looks like.

Limited Security Controls on IoT, OT, and IoMT Devices

Many of these devices are unable to run traditional endpoint security agents, support encryption, or receive regular patches. They are left to communicate internally with little to no built-in protection.

Legacy and Unpatched OT Systems

OT environments often run on older, purpose-built systems designed for uptime and reliability rather than security. This leaves known vulnerabilities in place for years and creates easy pivot points once attackers are already inside the network.

Device Diversity and Sheer Volume

IoT, OT, and IoMT environments often involve thousands of devices from different manufacturers, running different firmware and protocols. With so many diverse devices, security teams struggle to apply consistent monitoring, policy, or segmentation across the board.

Difficulty Applying Traditional Segmentation

Many IoT, OT, and IoMT devices weren’t designed to support modern segmentation or zero trust models, and taking them offline to reconfigure isn’t always an option – especially in OT environments where uptime is critical to safety or production.

Best Practices For Improving East-West Traffic Security In Complex Environments

While managing east-west traffic can be challenging, following these best practices enables security teams to implement controls that mitigate risk.

Implement Network Segmentation

Dividing a network into smaller zones limits how far an attacker can move. With network segmentation, one compromised device limits an attack’s blast radius.