Organizational perimeters have transformed. From IoT devices and cloud infrastructure to APIs and microservices, today’s perimeters bear little resemblance to those of even the recent past — and one result of these transformations are organizations’ vastly expanded attack surfaces.
Additionally, the adoption of hybrid work has imposed new requirements and introduced new challenges that influence perimeter architecture and tooling. Even as return-to-office (RTO) initiatives draw some workers back, extended and partially remote workforces remain common, making the need for off-premises security even greater.
As threat actors target organizations’ legacy VPN gateways and other edge devices with an increasing arsenal of remote access tools and tactics, organizations are bracing for a breakdown of their perimeter. However, with careful attention to detail and the incorporation of current best practices, organizations can provide better protection for their perimeter and edge devices without sacrificing the security of the rest of their environment.
What Is a Security Perimeter?
In cybersecurity, a perimeter refers to the boundary that separates an organization’s internal network from the internet, and perimeter security devices and applications keep threat actors from breaching that boundary by protecting, filtering, and controlling access to the internal network.
Historically, network perimeters were well-defined, encompassing all systems and devices within a specific geographical location, such as a company’s headquarters or data center. In this landscape, securing an organization meant creating defenses built around this clearly defined on-premises perimeter to prevent unauthorized external access. Legacy cybersecurity tools like firewalls and web gateways were essential solutions for protecting this type of perimeter.
However, with advancements in cloud computing, remote work, and mobile devices, the traditional concept of an on-premises perimeter is becoming obsolete, and the modern threat landscape finds security teams now tasked with protecting a growing, shifting perimeter where the boundary lines are blurred or even non-existent.
Common Types of Perimeter Security Solutions:
- Firewalls: These devices inspect and filter network and application traffic based on security policies to prevent unauthorized access.
- Intrusion Detection and Prevention Systems (IDS/IPS): Like antivirus for network traffic, these solutions seek out and block known malicious patterns within traffic flows.
- Virtual Private Network (VPN) Gateway: These create and manage secure VPN connections for remote users, encrypt traffic, and enable private communication over public networks.
What Is an Edge Device?
If a perimeter is the entire boundary between an organization’s internal network and the internet, and a perimeter tool is tasked with protecting that entire boundary, an edge device is anything that sits on that boundary (or edge) at a specific point where data crosses it. These devices play a crucial role in managing, filtering, and securing network traffic before it reaches internal systems. With the increasing adoption of the Internet of Things (IoT), cloud computing, and edge computing, edge devices have become critical components of modern cybersecurity strategies.
Common Types of Edge Devices
Edge devices come in various forms, each serving specific functions. Some of the most common types include:
- Router: A router connects different networks together, typically linking a local network to the internet. While primarily used for traffic routing, it can also perform basic security functions like network address translation (NAT) and access control lists (ACLs).
- Web Server: A web server maintains and delivers digital content, handles incoming traffic, improves response times through caching, and supports secure, efficient access to business-critical applications and services.
- Endpoints: Computers, mobile devices, and IoT devices — like sensors, cameras, and smart appliances — are all considered edge devices, as they allow connections to the internet and allow the internet to connect with an organization’s network.
A simple way to think of the difference between edge devices and perimeter tools is that edge security devices are tasked with protecting data traffic at specific points on the perimeter, whereas perimeter tools analyze and monitor all of an organization’s edge devices.
How Threat Actors Exploit Perimeters and Edge Devices
Threat actors exploit perimeter tools and edge devices by identifying weaknesses such as unpatched vulnerabilities, misconfigurations, poor credential management, and lack of visibility. Because these systems often serve as the first layer of defense — or the entry point into internal networks — any compromise can lead to severe consequences. Understanding how threat actors commonly exploit them is key to strengthening perimeter and edge cybersecurity.
Reconnaissance
Before initiating an attack, cybercriminals typically gather information to understand the target’s network layout and external-facing infrastructure. This intelligence-gathering phase enables attackers to pinpoint high-risk assets, particularly those with known security gaps or outdated software. Below are a few common approaches.
- Passive Intelligence Gathering: Threat actors use open-source intelligence (OSINT) tools to identify external IP addresses, discover exposed edge devices, and detect security tools deployed at the perimeter.
- Service Identification (Banner Grabbing): Tools like Nmap or Shodan are employed to inspect open ports and collect metadata, helping attackers determine the software versions and device types in use.
- Domain and Registry Lookups: DNS records and WHOIS data can reveal domain structure, email servers, VPN access points, and other internet-exposed services.
Leveraging Known and Unknown Vulnerabilities
Many devices, including those at the edge, often miss timely software and firmware updates , leaving them open to exploitation. Unpatched or poorly maintained endpoints or perimeter tools present a direct path into internal environments, bypassing traditional security controls.
- Exploitation of Known Vulnerabilities: Threat actors scan for systems that haven’t been patched against publicly disclosed vulnerabilities (CVEs), targeting any number of devices including firewalls, routers, and VPN concentrators and connectors.
- Zero-Day Attacks: More sophisticated groups, such as nation-state actors, may deploy exploits for previously unknown flaws, especially in widely used perimeter security technologies.
Credential Theft and Misuse
Compromising user credentials remains one of the most effective ways to bypass security boundaries. With valid credentials, attackers can impersonate authorized users and move through systems unnoticed.
- Phishing Techniques: Cybercriminals craft deceptive emails to trick users into revealing login details for remote access systems, like VPNs or cloud portals.
- Brute-Force and Password Spraying Attacks: By systematically attempting commonly used or leaked passwords, attackers target authentication portals such as SSH, RDP, and VPN gateways.
- Credential Stuffing: Previously compromised usernames and passwords are used in automated attacks, particularly where multi-factor authentication (MFA) is not enforced.
Misconfiguration Exploitation
Even updated systems can be exploited if they are not set up correctly. Misconfigured systems continue to be a significant factor in granting threat actors access and enabling successful cyber attacks.
- Default Settings and Open Interfaces: Exposed administrative ports or unchanged default credentials on edge devices and firewalls are commonly abused entry points.
- Overly Broad Firewall Rules: Loose or overly permissive configurations may allow unnecessary external or outbound access, facilitating data leakage or malware communication.
- Disabled or Inactive Security Features: Performance or operational concerns may lead organizations to turn off features like intrusion prevention or encrypted packet inspection, giving attackers more room to operate undetected.
Establishing Persistence
After initial access is achieved, attackers typically seek to maintain long-term access to the environment. Maintaining persistence enables prolonged surveillance, repeated data theft, or additional exploitation over time.
- Tampering with Firmware: Persistent malware can be embedded into the firmware of routers, firewalls, or switches, making it resilient to reboots and traditional clean-up efforts.
- Leveraging Reverse Shells and Remote Tools: Tools such as remote access trojans (RATs) or reverse shells are installed on edge devices, allowing ongoing control from outside the network.
- Creating Hidden Access Paths: Attackers may set up unauthorized administrator accounts or install SSH keys to enable future reentry.
Lateral Movement
Perimeter tools and edge devices remain key exploit targets even after a threat actor has breached an environment, allowing adversaries to extend their reach and ultimately access sensitive systems and data.
- Pivoting from Compromised Edge Devices: Edge-based systems, such as IoT devices or unmonitored routers, can serve as launchpads for further exploration of the internal environment.
- Exploiting Trust: If edge devices are granted excessive trust or access rights, attackers can use them to interact with critical internal systems.
- Credential Harvesting: Tools like Mimikatz are often deployed from within compromised systems to extract passwords or session tokens for deeper network penetration.
Exfiltration and Command-and-Control (C2)
With access and control established, attackers often use edge and perimeter devices to manage data theft or sustain their operations, in part because incoming activity is often more closely monitored than outgoing activity, making outbound exfiltration or C2 traffic harder to detect.
- Encrypted Channels: To avoid detection, attackers often move stolen data over encrypted tunnels such as VPNs or HTTPs, blending into legitimate network traffic.
- DNS and HTTP Tunneling: These common protocols are manipulated to disguise command-and-control communication or exfiltration efforts.
- Using Edge Devices as Proxies or Relays: Compromised devices, especially IoT or mobile devices, are repurposed to relay commands or data, forming part of the attacker’s infrastructure.
Explore in-depth how threat actors exploit edge devices and how early detection can reduce risk with the 2025 Arctic Wolf Security Operations Report.
How To Protect Your Organization’s Perimeter and Edge Devices
While traditional, firewall-focused perimeter security was effective in a time when networks were more centralized and localized, the shift toward cloud computing and remote work demands a more adaptive approach. Consider the following tactics to better protect your perimeter and edge devices.
1. Network Segmentation
Network segmentation is the division of an organization’s network architecture into subnets. Each of these subnets is its own, albeit smaller, network. These networks are interconnected, but physical and/or virtual boundaries allow for network traffic and network policies to be more precisely managed and controlled. This kind of segmentation can help prevent unauthorized users from accessing specific network-connected resources like databases and applications and creates micro-perimeters around critical assets and network components, isolating them from each other.
Network segmentation is broken up into two general types:
- Physical segmentation is when the network is physically broken into subnets using a firewall (which acts as a gateway for traffic) or other devices such as routers and switches. This is also known as perimeter segmentation. However, as the volume of endpoints grows, the yes/no nature of this kind of segmentation can prove ineffective.
- Logical segmentation, also called virtual segmentation, uses virtual local area networks (VLANs) to automatically send traffic to various subnets, creating more granular and specific segmentation.
By segmenting an organization’s network, critical systems and data can be isolated, thereby minimizing the potential for lateral movement if an attacker gains access to one part of the environment. Perimeter devices serve as enforcement points that help maintain segmentation boundaries.
2. Zero Trust
Zero trust is a cybersecurity strategy that works to eliminate the concept of trust within an IT environment, relying on point-in-time verification, control, and restriction of access, never trusting that anyone should have default or continuous access to any application or data source. Instead, zero trust frameworks require that access to each system, data, or application be assessed and verified in context on an ongoing basis, ideally preventing threat actors from exploiting any trust-based access policy to gain access undetected.
A zero trust framework relies on various technologies and tools to hold every user and access request to a rigorous level of scrutiny when trying to access a system, program, or asset. In addition to an external-only security architecture (where the perimeter of a network, not internal access points, is defended), zero trust also employs controls at internal access points within a system.
A good example of zero trust is the access controls central to a strong identity and access management (IAM) system, and how those access controls are deployed and maintained within an environment. In a zero trust framework, each user, regardless of whether the user is directly connected to the on-premises network or connecting from a remote location, not only would need credentials to access a particular application, but would also need to undergo identity verification through a secondary control, such as multi-factor authentication (MFA).
3. Patch Management
Edge devices commonly run specialized operating systems or firmware that can become vulnerable over time if not properly maintained, making them attractive targets for threat actors. Leaving known vulnerabilities unpatched — particularly in firewalls, VPN appliances, or gateways — can expose the organization to preventable attacks.
In 76% of intrusion cases investigated by Arctic Wolf® Incident Response, threat actors employed at least one of 10 specific vulnerabilities for which patches were widely available.
A robust patching strategy, one that applies updates to firmware and software on a timely, risk-informed basis, as well as one that tests patches in a controlled environment to prevent unintended disruptions, can help proactively protect your perimeter and edge devices. Automated patch management tools can streamline this process and reduce human error.
4. Enforcing Multi-Factor Authentication (MFA)
Access to critical infrastructure, particularly administrative functions on edge devices and perimeter systems, must be safeguarded with more than just passwords.
MFA adds another crucial verification layer. Even if user credentials are compromised, MFA provides an extra step — typically through biometrics, mobile apps, or hardware tokens — that makes unauthorized access more difficult.
All remote interfaces, VPNs, and administrative portals should require MFA. Combined with strong password hygiene and credential lifecycle management, this approach greatly reduces the risk of credential-based attacks.
5. Inventory Management
You can’t protect what you can’t see — or if you don’t even know what exists. Maintaining a complete inventory of perimeter and edge assets is a foundational security step. An up-to-date inventory allows for faster vulnerability assessments, improved patch workflows, and better incident response.
Each device and tool should be cataloged with information such as manufacturer, firmware version, location, patch status, and assigned role. Asset tracking tools can help automate device lifecycle management and ensure decommissioned or shadow IT devices are not left active and vulnerable.
6. Security Awareness Training
Tools alone can’t guarantee perimeter and edge device security. An organization’s people play a crucial role in proactive protection. Continuous security awareness education (meaning a program that is conducted weekly or monthly, not just annually) combined with regular phishing simulations significantly increases the ability of employees to make proactive choices that adhere to more secure standards, a potent first line of defense in protecting endpoints — the most frequently targeted edge device.
Many security training solutions are priced by tiers, allowing you to access certain features or different amounts of content based on what you pay. Purchasing a once-a-year training course will be cheaper, but it’s unlikely it will help your employees keep security top of mind, especially if your organization is prone to phishing attempts or has vast compliance considerations. Similarly, if you choose a more robust solution doesn’t come with any expert support, the cost may be lower. However, the number of hours required by your IT team to manage it can add to what may already be a heavy workload.
An effective security training program should include:
- New and relevant security awareness content delivered in frequent, brief sessions lasting no more than five minutes to ensure maximum retention and participation
- Phishing simulations with specific and immediate follow-up training that doesn’t shame the user for making a mistake
- A fully managed, friction-free experience for employees and administrators with minimal barriers to participation and minimal in-house management
- Promoting a security-first culture across all levels of the organization enhances resilience and helps reduce the likelihood of successful attacks.
7. Real-Time, Continuous Monitoring
Visibility into device behavior and network traffic is vital for early threat detection. Without it, attackers can operate unnoticed for extended periods.
Monitoring your network 24×7 is critical to your ability to respond to threats effectively. If a perimeter tool or edge device becomes compromised, you need to be able to identify the problem quickly and stop the attack from spreading. Considering that 51% of alerts occur outside traditional working hours, 24×7 coverage is not optional, it’s critical.
Around-the-clock monitoring is even more important when many employees work from home or travel with endpoints, logging on from networks far removed geographically from the home office.
However, 24×7 eyes-on-glass coverage for an organizational perimeter can be a challenge for even the most well-resourced organizations. Because of this, many organizations are turning to managed detection and response (MDR) solutions, which provide 24×7 monitoring of your networks, endpoints, perimeter, and cloud environments to help you detect and respond to modern cyber attacks.
8. Endpoint Security
The makes and models of endpoints vary widely, as does the operating system, the apps or programs installed on them, and the security habits of each endpoint user. The rise of hybrid work has increased these challenges, as endpoints have become more portable – and more exposed – than ever before. That’s why endpoint security is so foundational to cybersecurity. Monitoring and securing the array of endpoints throughout your environment allows you to prevent many common threats and detect advanced threats as early as possible, stopping them before they go from isolated compromises to network-wide security incidents.
Benefits of endpoint security include:
- When fully deployed, it protects endpoints across a network or organization
- It helps secure devices in an age of hybrid and remote work
- It offers more sophisticated threat protection, detection, and response
- It protects users’ identities or credentials which may be present on an endpoint, now a major target for threat actors
- Protects the valuable data, operational functions and access points to a broader network an endpoint offers.
Explore the common types of endpoint security solutions.
How Arctic Wolf Can Help
Perimeter tools and edge devices serve as the first line of defense in a rapidly evolving digital environment, and their protection isn’t a one-time project. Rather, their security is a continuous commitment to resilience, vigilance, and security-driven design. It’s also something that can benefit from having a partner — like the leader in managed security operations.
Discover how our integrations with cybersecurity leaders like Okta and Zscaler enable hybrid and remote work without sacrificing identity security.
Learn more about the AI-driven prevention, detection, and response provided by Aurora™ Endpoint Security, designed to stop endpoint threats before they disrupt your business.
Demo Arctic Wolf® Managed Risk and see how it empowers you to discover, assess, and harden your environment against digital risks by contextualizing the attack surface coverage across your networks, endpoints, and cloud environments.
Explore how Arctic Wolf® Managed Detection and Response helps address the most critical cybersecurity challenges organizations face, including the security of their perimeter and edge devices.
