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Partner Post: NETSCOUT's Blog Is Overreliance on Perimeter-Based Security Undermining Your Security Efforts?

Author: Robert Derby, Senior Product Marketing Manager

In today’s world, we regularly encounter headlines about major security breaches across various industries, spanning government agencies, consumer goods, finance, gaming, and more. It’s evident that no industry is immune to these threats. However, what often goes unnoticed is that the most significant damage occurs once malicious actors gain initial access to a network.

Many organizations rely primarily on perimeter-based firewalls or intrusion prevention methods, believing this to be the ultimate defense. Yet, the notion of achieving 100 percent threat prevention is a fallacy. Although preventive measures are crucial, the true impact and highest return on investment (ROI) come from internal network visibility technologies—a facet often underestimated. Detecting, investigating, and responding to breaches constitute essential components of the cybersecurity ecosystem because they significantly mitigate the consequences of potential breaches.

This blog delves into the limitations of perimeter-based cybersecurity and underscores the critical role of packet-based internal traffic monitoring in upholding a robust and effective security posture.

Perimeter-based Cybersecurity: What It Is and How to Address Its Limitations

Perimeter-based cybersecurity revolves around the idea of securing an organization’s network by fortifying the outer boundaries. This approach typically includes the following elements:

  • Firewalls: Firewalls are the gatekeepers that filter incoming and outgoing network traffic. They are designed to block malicious traffic and allow legitimate traffic to pass through.
  • Intrusion detection systems (IDS) and intrusion prevention systems (IPS): IDS monitors network traffic for suspicious activity, while IPS actively blocks or mitigates potential threats.
  • VPNs (virtual private networks): VPNs create secure tunnels for remote access, ensuring that data transmitted between remote locations and the central network remains encrypted and secure.
  • Antivirus and antimalware solutions: These tools are used to detect and prevent malware infections at the perimeter, often scanning incoming files and emails.
  • Network access controls: These measures dictate who can access the network and what resources they can access.

Although perimeter-based cybersecurity is crucial, it has limitations that organizations must acknowledge, such as:

  • Reconnaissance: Attackers often gather information about the target organization via techniques such as social engineering, which can go undetected by perimeter defenses because it involves human-based manipulation and deception. Internal traffic monitoring can detect unusual activity.
  • Lateral movement: Once inside the network, attackers can move laterally, evading perimeter defenses. Internal traffic monitoring is crucial for detecting such lateral movements.
  • Zero-day attacks: Perimeter defenses are often less effective against zero-day attacks, which exploit vulnerabilities that are unknown to security vendors.
  • Advanced persistent threats (APTs): Determined attackers can bypass perimeter defenses by using sophisticated techniques, making it essential to monitor internal traffic for signs of compromise.
  • Insider threats: Perimeter defenses focus on external threats, leaving organizations vulnerable to insider threats—malicious or careless employees who have legitimate access to the network.
  • MITRE ATT&CK framework mapping: After the Initial access and execution phase, perimeter-based protection is blind to most activity, because attackers operate within the network, exploiting techniques detailed in the MITRE ATT&CK framework. Internal network monitoring is essential for recognizing these tactics, allowing security teams to respond effectively and prevent further advancement through the attack chain.

To address these limitations and create a more robust security posture, organizations must prioritize internal traffic monitoring. Here’s why this is crucial:

  • Early threat detection: Internal traffic monitoring can identify suspicious activities and anomalies within the network, allowing for early threat detection before significant damage occurs.
  • Lateral-movement detection: Detecting lateral movement within the network is possible only via internal traffic monitoring, allowing for swift containment and response to threats.
  • APT detection: Advanced persistent threats often go undetected by perimeter defenses. Internal traffic monitoring can identify unusual patterns of behavior that might indicate an APT attack.
  • Zero-day attack defense: By monitoring internal traffic, organizations can detect zero-day attacks that bypass perimeter defenses, helping them respond promptly.
  • Insider threat mitigation: Monitoring internal traffic helps identify insider threats, enabling organizations to take proactive measures to prevent data breaches or other security incidents.


Omnis Cyber Intelligence (OCI) and Omnis CyberStream form a powerful cybersecurity platform for comprehensive, packet-based network visibility, threat detection, and response. With deep packet inspection (DPI) at its core, this solution not only provides unparalleled security visibility across the network perimeter (where it sees north-south traffic) but also can cost-effectively scale to provide visibility into the internal network (east-west traffic)—including multicloud and hybrid cloud—and detect known and emerging threats with precision. Combined with multidimensional threat analytics at the source of Omnis CyberStream packet capture—which includes known indicators of compromise (IOCs), detection of known vulnerable protocols, and behavioral analytics—the OCI solution can detect both known and unknown threats across your entire network environment. Seamless integration with security information and event management (SIEM); security orchestration, automation, and response (SOAR); and extended detection and response (XDR) tools enhance incident response, while OCI centralizes event management and historical analytics in a single user interface. In a world where cyberthreats and risks constantly evolve, OCI empowers organizations to protect their networks and data effectively, minimizing vulnerabilities and fortifying their security posture.

See how NETSCOUT network and security solutions can make a difference in your organization.


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