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How to fix misconfigured firewalls (and prevent firewall breaches)


Firewall misconfigurations are one of the most common and preventable security issues that organizations face.

Comprehensively managing access control, addressing vulnerabilities, and detecting configuration mistakes under these conditions is not easy

It’s especially challenging for organizations that use the default firewall rules provided by their vendor.

Your firewall policies should reflect your organization’s unique cybersecurity risk profile. This requires some degree of customization, and intelligence into kinds of cyber attacks hackers use to target your organization.

Understanding security misconfigurations and their impact on network security

Security misconfigurations happen when elements of your security tech stack expose preventable vulnerabilities that hackers can exploit. These misconfigurations can take a variety of forms, putting a wide range of security tools and open ports at risk.

Network firewall misconfigurations can have a wide-ranging impact on your organization’s overall security posture. Hackers that target vulnerable infrastructure pose a threat to the entire application stack. They may be able to gain access to network services, application servers, and virtual machines. Depending on the specific misconfiguration, they may be able to compromise hardware routers and endpoints as well.

In organizations with complex firewall deployments, attackers may be able to exploit misconfigurations, bypass security policies, and escalate their own privileges to make arbitrary changes to firewall security.

From this point, attackers can easily modify access control lists (ACLs) to specifically allow the malware they wish to run, compromising the first line of defense against data breaches.

This is exactly why Gartner recommends implementing a centralized solution for firewall management. Centralized visibility and control is crucial for maintaining effective firewall configurations and updating them accordingly.

Otherwise, ensuring compliance with security best practices like the principle of least privilege becomes difficult or impossible. Routing network traffic through complex cloud-native infrastructure securely requires deep visibility into firewall configuration status, effective authentication processes, and automation-friendly security solutions.

How hackers exploit misconfigured firewalls

Common misconfigurations include implementing overly permissive rules, disabling critical security features, and neglecting to protect open ports against unauthorized access. This leaves organizations vulnerable to Distributed Denial-of-Service (DDoS) attacks, remote control, and data breaches.

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Here are some of the ways cybercriminals can exploit misconfigured firewalls:

1. Taking advantage of permissions misconfigurations

Overly permissive firewall rules are a common problem among organizations with complex cloud-enabled infrastructure. Often, the organization’s demand for productivity and connectivity take precedence over the need to protect sensitive data from unauthorized network traffic.

Additionally, IT team members may misunderstand the cloud provider’s shared responsibility model and assume that the provider has already secured the data center from all potential threats.

These situations are particularly risky when the organization is undergoing change. For example, many security professionals start with completely open permissions and tighten them as they learn more about the network’s needs. Obvious and highly visible permissions get secured first, while less visible parts of the security framework are deprioritized – or never addressed at all.

Hackers can exploit this situation by focusing on less obvious access points first. Instead of sending malicious traffic to IP addresses associated with core business servers, they might infiltrate the network through an unsecured API, or look for an unpatched operating system somewhere in the network.

2. Exploiting disabled security features

Many firewalls offer advanced security features to organizations willing to configure them. However, security teams are often strained for time and resources. They may already be flooded with a backlog of high-priority security alerts to address, making it challenging to spend extra time configuring advanced firewall policies or fine-tuning their security posture.

Even organizations that can enable advanced features don’t always do it. Features like leak detection and port scan alerts can put additional strain on limited computing resources, impacting performance. Other features may generate false positives, which only add to the security workload.

But many of these features offer clear benefits to organizations that use them. Sophisticated technologies like application and identity-based inspection allow organizations to prioritize firewall performance more efficiently throughout the network.

If threat actors find out that advanced security features like these are disabled, they are free to deploy the attack techniques these features protect against. For example, in the case of identity-based inspection, a hacker may be able to impersonate an unidentified administrator-level account and gain access to sensitive security controls without additional authentication.

3. Scanning for unsecured open ports

Hackers use specialized penetration testing tools to scan for open ports. Tools like Nmap, Unicornscan, and Angry IP Scanner can find open ports and determine the security controls that apply to them. If a hacker finds out that your ACLs neglect to cover a particular port, they will immediately look for ways to exploit that vulnerability and gain access to your network.

These tools are the same network discovery tools that system administrators and network engineers use on a routine basis. Tools like Nmap allow IT professionals to run security audits on local and remote networks, identifying hosts responding to network requests, discovering operating system names and versions, and more. Threat actors can even determine what kind of apps are running and find the version number of those apps.

They also allow threat actors to collect data on weak points in your organization’s security defenses. For example, they might identify a healthcare organization using an outdated app to store sensitive clinical trial data. From there, it’s easy to look up the latest patch data to find out what exploits the outdated app is vulnerable to.

How to optimize firewall configuration

Protecting your organization from firewall breaches demands paying close attention to the policies, patch versions, and additional features your firewall provider offers. Here are three steps security leaders can take to address misconfiguration risks and ensure a robust security posture against external threats:

1. Audit your firewall policies regularly

This is especially important for organizations undergoing the transition to cloud-native infrastructure. It’s virtually guaranteed that certain rules and permissions will no longer be needed as the organization adjusts to this period of change over time. Make sure that your firewall rules are constantly updated to address these changes and adapt to them accordingly.

Auditing should take place under a strict change management framework. Implement a change log and incorporate it into your firewall auditing workflow so that you can easily access information about historical configuration changes.

This change log will provide security professionals with readymade data about who implemented configuration changes, what time those changes took place, and why they were made in the first place. This gives you at-a-glance coverage of historical firewall performance, which puts you one step closer to building a unified, centralized solution for handling firewall policies.

2. Update and patch firewall software frequently

Like every element in your security tech stack, firewall software needs to be updated promptly when developers release new patches. This applies both to hardware firewalls operating on-premises and software firewalls working throughout your network.

These patches address known vulnerabilities, and they are often the first line of defense against rapidly emerging threats. The sooner you can deploy software patches to your firewalls, the more robust your network security posture will be.

These changes should also be noted in a change log. This provides valuable evidence for the strength of your security posture against known emerging threats. If hackers start testing your defenses by abusing known post-patch vulnerabilities, you will be prepared for them.

3. Implement an intrusion detection system (IDS)

Firewalls form the foundation of good network security, and intrusion detection systems supplement their capabilities by providing an additional line of defense. Organizations with robust IDS capabilities are much harder to compromise without triggering alerts.

IDS solutions passively monitor traffic for signs of potential threats. When they detect a threat, they generate an alert, allowing security operations personnel to investigate and respond. This adds additional layers of value to the basic function of the firewall – allowing or denying traffic based on ACLs and network security rules.

Many next-generation firewalls include intrusion detection system capabilities as part of an integrated solutions. This simplifies security management considerably and reduces the number of different devices and technologies security teams must gain familiarity with.

Pay attention to firewall limitations – and prepare for them

Properly configured firewalls offer valuable security performance to organizations with complex network infrastructure. However, they can’t prevent every cyber attack and block every bit of malicious code. Security leaders should be aware of firewall limitations and deploy security measures that compensate appropriately.

Even with properly configured firewalls, you’ll have to address some of the following issues:

Zero-day attacks

Firewalls may not block attacks that exploit new and undiscovered vulnerabilities. Since these are not previously known vulnerabilities, security teams have not yet had time to develop patches or fixes that address them. These types of attacks are generally able to bypass more firewall solutions.

However, some next-generation firewalls do offer advanced features capable of addressing zero-day attacks. Identity-based inspection is one example of a firewall technology that can detect these attacks because it enforces security policies based on user identity rather than IP address. Sandboxes are another next-generation firewall technology capable of blocking zero-day attacks.

However, no single technology can reliably block 100% of all zero-day attacks. Some solutions are better-equipped to handle these types of attacks than others, but it takes a robust multi-layered security posture to consistently protect against unknown threats.

Timely incident response

Firewall configuration plays an important role in incident response. Properly configured firewalls help provide visibility into your security posture in real-time, enabling security teams to create high-performance incident response playbooks. Custom playbooks ensure timely incident response by prioritizing the types of threats found in real-world firewall data.

If your firewalls are misconfigured, your incident response playbooks may reflect a risk profile that doesn’t match with your real-world security posture. This can lead to security complications that reduce the effectiveness of incident response processes down the line.

Planned outages when updating firewalls

Updating firewalls is an important part of maintaining an optimal firewall configuration for your organization. However, the update process can be lengthy. At the same time, it usually requires scheduling an outage in advance, which will temporarily expose your organization to the threats your firewall normally protects against.

In some cases, there may be compatibility issues with incoming version of the firewall software being updated. This may lengthen the amount of time that the organization has to endure a service outage, which complicates firewall security. This is one reason why many security leaders intentionally delay updating their firewalls.

As with many other aspects of running and maintaining good security policies, effective change management is an important aspect of planning firewall updates. Security leaders should stagger their scheduled updates to avoid reducing risk exposure and provide the organization with meaningful security controls during the update process.

Automate change management and avoid misconfigurations with algoSec

AlgoSec helps organizations deploy security policy changes while maintaining accuracy and control over their security posture. Use automation to update firewall configuration policies, download new security patches, and validate results without spending additional time and energy on manual processes.

AlgoSec’s Firewall Analyzer gives you the ability to discover and map business applications throughout your network. Find out how new security policies will impact traffic and perform detailed simulations of potential security scenarios with unlimited visibility. Schedule a demo to see AlgoSec in action for yourself.

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