Keeping your attack surfaces under control is all about safeguarding the avenues through which adversaries can gain unauthorized access to information technology systems. Modern application environments can have a seemingly infinite number of entry points, spanning individual chunks of code, third-party tools, API hooks and everything in between, making them extremely challenging to secure.
Danger lurks everywhere, and managing the attack surface means securing every possible route into and out of the network. This includes digital attack surfaces such as the vulnerabilities in software code, applications and APIs, plus the physical surfaces that consist of hardware such as laptops, mobile devices, networking equipment, servers and other assets.
It also refers to human attack surfaces – namely employees and contractors given access to networks, who might be susceptible to phishing emails, social engineering attacks and other tricks.
To optimize attack surface management, security teams must adopt a focused and programmatic approach that secures every potential entry point. ASM, as it’s known, boils down to seven key steps that every organization should take to minimize its risk posture.
1. Inventory and Minimize Every Entry Point
Teams cannot secure something if they don’t know it exists. Attack surface management starts with creating and maintaining a complete inventory of every possible route into the network. This includes all accounts, assets and systems that might be able to gain access.
Creating this inventory is the hard part, as it involves systematically identifying legacy applications, outdated operating systems, routers and ports and working out who has access to them.
Once the inventory is complete, the next step is to minimize its complexity. That means identifying and retiring legacy and redundant systems, unless they have specific approval to be retained from the highest level. To manage access, users and systems should be assigned to defined groups in order to enforce the “principle of least privilege” using a modern Identity and Access Management tool.
This will ensure that each user only has access to the bare minimum necessary to perform their jobs. The same principle should also be applied to the applications and system access controls, with secrets securely stored using robust password managers.
2. Implement Zero-Trust Access Controls
Zero-trust security principles assume all users are compromised. Under this security model, the objective is to continuously limit what resources and systems they’re able to access to only what’s strictly necessary. It also involves continuously monitoring for anomalous activity that might indicate a breach.
To establish a robust zero-trust security model, organizations need to compile an inventory of all infrastructure assets and a complete map of their network topography. Each security tool should be documented too, and teams should evaluate its purpose and effectiveness. Access controls must be defined based on data classification to ensure a clear understanding of who is authorized to access what.
Finally, organizations should apply multi-factor authentication universally and enroll every new user and device, providing them with an identity before they’re granted access to any internal resource.
3. Implement Network Segmentation
Network segmentation means chopping up the network into smaller, isolated subnetworks in order to prevent lateral movement if an attacker gains access. It’s achieved by creating discrete “zones” and protecting each one with its own firewall that’s configured to block all unauthorized traffic.
In the event that a subnetwork is breached, the attacker only gains access to a small part of the network, reducing the blast radius of malware and other threats.
Standard network segmentation is designed to prohibit “north-south” traffic, preventing anything from entering or exiting. It can be further enhanced through microsegmentation, which extends this protection to “east-west” traffic, restricting the flow of data between applications and individual devices within the subnetwork.
It ensures, for example, that an IoT device can only talk to its designated server, preventing it from sending data to any other system.
4. Set Up Comprehensive Monitoring
Teams must have the ability to generate instant alerts for critical events, such as any newly exposed assets, so they can take immediate action to remediate the threat. Doing this means implementing a continuous monitoring system that supports both scheduled and ad-hoc scanning to identify network assets.
The system should provide comprehensive reports, and risks should be graded based on their severity level. It should also provide recommended remediations to automate vulnerability management. To aid with this, teams should create a documented remediation plan for each type of vulnerability.
Full network visibility is vital, and that requires a comprehensive understanding of its layout and every ingress and egress point. That said, teams should ensure that mission-critical servers and their applications are given the highest priority and schedule vulnerability scans accordingly.
5. Enhance Default Software and Asset Configurations
IT assets such as operating systems, servers, SaaS applications, end-user devices, network switches and IoT sensors are usually shipped with a default configuration that prioritizes simple deployment rather than security.
Leaving new assets in this state is extremely risky, as it exposes them to insecure basic controls, open services and ports, default security credentials and vulnerable pre-configured DNS settings. If these assets aren’t reconfigured before deployment, they dramatically increase the potential attack surface.
The Control 4: Secure Configuration of Enterprise Assets and Software of CIS Controls v8 framework recommends developing and enforcing robust initial configurations and employing continuous configuration management to ensure they maintain a resilient security posture.
6. Enforce Policy Compliance
Remote and hybrid work models have led to an explosion in the number of endpoints and a significant expansion of the attack surface. Strict policy enforcement becomes extremely important when a significant number of employees are operating outside of the traditional network perimeter.
To ensure policy compliance, teams should implement a robust unified endpoint management or UEM tool that automatically enforces security and access rules. These tools can also be helpful for identifying, managing and reducing the attack surface. For instance, they offer comprehensive visibility into IT assets and users, identifying every device and worker that gains access to the network.
Furthermore, UEM tools can be used to provision new devices with the necessary access permissions and implement software updates over-the-air, ensuring they receive essential security upgrades at the appropriate time. They can also securely wipe any device that’s decommissioned from the network, preventing it from being used to gain access after it’s discarded.
7. Enhance Employee Awareness
In many cases, the weakest link in network security is not an endpoint, a device or a firewall, but the person accessing it. Employees are granted permission to access the most critical systems and data to perform their work, and this makes them high-value targets.
However, these employees are only a weak link if they lack adequate security awareness, and it’s the responsibility of the security team to ensure everyone’s invested in maintaining an air-tight human firewall. This means creating appropriate training programs to educate employees on how to identify and mitigate threats such as phishing emails or social engineering attacks.
It doesn’t stop there though, for employees’ security knowledge should be reinforced by posting relevant security tips when appropriate and carrying out regular phishing attack simulations to prevent complacency.
The Foundation of Proactive Resilience
Attack surface management has become one of the foundational tenets of modern network security. In today’s era of distributed cloud environments and remote workforces, the traditional perimeter-based defense model is no longer sufficient to protect mission-critical applications, systems and data.
Security teams need to prioritize the continuous identification of exploitable assets, create a comprehensive inventory and attempt to minimize the attack surface wherever possible. Doing this moves helps organizations to shift from a reactive security posture towards proactive resilience.
By systematically refining attack surface management practices, organizations can build a security-first culture and scale their cyber defenses alongside their digital footprint, anticipate threats and harden critical systems before breaches occur.
