Firewall security measures are one of the most basic cyber protection tools that organizations of all sizes use to prevent data breaches and hacking. Network security firewalls filter out incoming traffic to prevent malicious files from being downloaded and block attackers from accessing sensitive systems.
There are many types of firewalls used in modern security architectures. Unfortunately, cyber criminals have a lot of experience in circumventing them as well. Many attackers know how to break a firewall—and some insider threats can bypass them entirely.
What are firewalls useful for, if they can be breached? When aren’t firewalls useful? How does firewall hacking work? Most importantly, what can you do to protect against hackers and the threats they pose to you network firewall security?
How Are Firewalls Useful in Ensuring Network Security?
As mentioned earlier, network security firewalls are useful as a kind of filter for incoming network traffic. These firewalls sit on the perimeter of your network, scanning incoming data packets for potential issues that could indicate a cyber threat. The specific way that these firewalls look for malicious data packets varies based on the firewall’s type.
For example, a simple packet-filtering firewall might just check the basic destination/origin metadata for an incoming packet without looking at the packet’s contents. Meanwhile, circuit-level gateway firewalls might check the packet’s handshake protocols (again, without inspecting the actual data in the packet). Deep-layer inspection firewalls look at the contents of the data packet to check for malware and other issues, which is better for finding malware, but has a higher resource draw to match.
When installed as a perimeter filter on the network, firewall security tools of all types can be instrumental for keeping casual intrusion attempts from succeeding. When installed on individual network security endpoints, firewalls can create strong internal segmentation that helps to slow down attackers that are already on the network (such as when insider attacks happen).
What Do Firewall Security Tools Protect Against?
Different types of firewalls will provide protection against different things. Some of the things that firewall security tools can protect against include:
Malware Insertion. Deep packet inspection firewalls can be enormously useful for identifying and stopping malware installation attempts from outside sources.
Insider Attacks. When network firewalls are installed on a per-app and/or per-endpoint basis, they create a defense in depth strategy that helps limit the spread of attacks that breach the perimeter—including insider attacks.
Data Exfiltration. Firewalls can check more than just incoming traffic. By checking outgoing traffic for suspicious activity (such as trying to export sensitive data to an outside server), perimeter firewalls can help detect and prevent data exfiltration from an advanced persistent threat (APT).
It’s important to note that these are just a few examples of the types of threats that network security firewalls can help to prevent. However, each of these use cases requires a specific type of firewall setup—and none are immune to firewall bypassing techniques.
What Can’t a Firewall Protect Against?
While useful as a basic cybersecurity measure, network firewall security tools can’t stop everything. As a matter of fact, attackers have spent years figuring out ways to bypass network and device-based firewalls entirely by using clever tactics or exploits.
Some examples of things that firewalls can’t protect against (at least, not 100%) include:
In most organizations, people are the weakest links in the cybersecurity chain—and cybercriminals know this. So, they launch phishing attacks against people in your network that use emails or social media to trick people into downloading malware, approving fake invoices, or surrendering sensitive data.
Malicious Use of Authorized Accounts/Devices
Most firewalls are configured to defend against outside threats. Thus, they often aren’t ready to guard against someone using a legitimate user account and/or pre-registered access device in a malicious manner. Internal firewalls can help curtail this, but they need to be carefully configured to stop malicious use while still allowing legitimate traffic to proceed unimpeded.
Distributed Denial of Service (DDoS) Attacks
DDoS attacks seek to overwhelm cybersecurity defenses via sheer weight of volume (or by leveraging certain exploits to overload target systems). While some firewalls can efficiently drop traffic without overly impacting network performance, others might actually make DDoS attacks worse by trying to scrutinize every data packet in detail. In either case, firewall security measures can only do so much in the face of an attack designed to overload their capabilities.
If there are previously-unknown exploits and vulnerabilities in either the firewall or the network assets it’s protecting, then attackers may be able to use them to breach the network. This is why vulnerability testing and management is so crucial to cybersecurity.
Direct Physical Access
If a cybercriminal can walk straight up to a computer, server, or data storage drive and take it, no amount of network security firewall solutions will ever be enough to protect your information.
So, to answer the question: “Can firewalls be hacked?” the short answer is: “yes.” Unfortunately, there are all too many cybercriminals who know how to hack a firewall or how to bypass it entirely to achieve their objectives.
How to Protect Against Firewall Bypassing Attacks
While there are plenty of firewall hacking or bypassing tricks that cybercriminals can use to break or get past your network firewalls, that doesn’t mean you’re completely helpless and that you shouldn’t bother. Instead, it’s important to recognize the risks you face and to take proactive measures to limit them.
Although there is no foolproof solution that will 100% guarantee that you’ll never face a cybersecurity breach, there are some things that you can do to manage your vulnerabilities and risk. Some specific things you can do to limit your risk include:
Using Multiple Firewall Solutions at Different Levels
No one firewall, no matter how robust, will ever be proof against all attacks. So, when creating a defense in depth strategy that segments your network and apps, consider using multiple firewall solutions so the same exploits and vulnerabilities won’t work against all of your network firewalls.
Stay on Top of Security Patches/Updates
Many attacks leverage known vulnerabilities in popular software and security tools. These vulnerabilities frequently have security patches that fix the issue, but many organizations are behind schedule on applying them (which leaves the organization vulnerable). By applying security patches to your hacker protection software, you can keep cybercriminals out more easily.
Set Strong Password Policies and Multifactor Authentication
Hijacked user accounts are a common tool for attackers to bypass firewall security tools. So, making it harder to steal and use account credentials can help limit the risk of a breach. Setting strong password policies (8+ characters long, use case-sensitive letters, adding special characters, etc.) and applying multifactor authentication can help prevent account hijacking.
Regularly Running Penetration Tests
Penetration testing can help identify previously-unknown security vulnerabilities in the apps and firewalls that your organization uses. Once discovered, you can start taking steps to close these security gaps (hopefully before an attacker can use them). Some common measures include applying custom patches to software code and firewall rules, or replacing the vulnerable solution with something that is better-protected.
These are just a few of the potential fixes for the different ways that hackers can bypass firewall security. Need help optimizing your cybersecurity strategy?