What are the Top Firewall Vulnerabilities and Threats?

Published on: March 5, 2022

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To secure their precious assets, businesses use network security techniques such as honeypots, firewalls, intrusion detection systems (IDS), and intrusion prevention systems. Enterprise networks, on the other hand, are the most popular targets for hackers looking to compromise a company's security, and attackers are always coming up with new techniques to penetrate network security.

A firewall is a software or hardware-based system that protects the assets of a private network from illegal access by users on other networks. It is positioned at the network gateway. It checks all packets entering or exiting the internal network and prohibits those that do not fulfill the security requirements. The firewall protects systems on one side of it from systems on the other side of the firewall if it is properly configured.

For auditing purposes, the firewall records all attempts to log into the network. Unauthorized login attempts can be detected by inserting an alert that triggers when an unauthorized person tries to log in. Firewalls can filter packets based on their destination address and the sort of content they include. When it comes to address filtering, they recognize source/destination IP addresses and port numbers, and when it comes to protocol filtering, they recognize different types of network traffic. The state and properties of data packets can be determined by firewalls.

Although having a firewall as part of your security plan is critical, firewalls may have some vulnerabilities. A firewall vulnerability is an error made during the design, implementation, or configuration of a firewall that can be used to attack the trusted network it is designed to protect. Drawbacks of a firewall system are as follows:

• A firewall cannot defend a network from internal threats such as backdoors. For example, a disgruntled employee colludes with an external attacker.

• If all connections flow through the firewall, a bottleneck may arise.

• If external devices such as laptops, USB drives, and other similar devices are already infected and linked to the network, a firewall will not be able to defend the network from these devices.

• The firewall is unable to fully protect the network against all sorts of zero-day malware.

• A firewall will be useless if the network design and settings are flawed.

• A firewall may not be able to prevent threats from common ports or applications.

• A firewall may not able to understand tunneled traffic.

Common firewall vulnerabilities and misconfigurations include:

• ICMP is allowed and the firewall can be pinged.

• Having unnecessary services available on the firewall.

• Having open TCP/UDP ports that aren't needed.

• The firewall returns Deny response rather than drop for the ports that are blocked. This provides the attacker with additional information or improves the speed of the attacker's port scan.

• Misconfiguration that allows a TCP ping of internal hosts with Internet-routable IP addresses.

• Trusting certain IP addresses.

Top 7 firewall vulnerabilities and threats are as follows:

1. DDoS Attacks
2. Insider Attacks
3. Outdated Firewall Software
4. Failure to Activate Controls
5. Lack of Documentation
6. Basic Inspection Protocols
7. Improper Configuration

Figure 1. Top 7 Firewall Vulnerabilities and Threats

In this article, we'll go through the weaknesses and vulnerabilities of firewall technology and many strategies for circumventing firewall protection, as well as the countermeasures that must be taken to avoid such attacks.

1. DDoS Attacks

DDoS attacks are a popular attack strategy that is noted for being both highly successful and low-cost to execute. The basic goal is to exhaust a defender's resources, resulting in a shutdown or prolonged inability to deliver services. Protocol attacks try to exhaust the resources of firewalls and load balancers, preventing them from processing valid data.

While firewalls can mitigate some types of DDoS attacks, they can still be overwhelmed by protocol attacks.

Tiny fragmentation is one of the methods used by hackers to evade firewalls. The size of an IP packet is frequently larger than the maximum size permitted by the underlying network. In these situations, the packet must be broken in order to be carried further. This feature of the TCP/IP protocol is used by the attacker. The attacker produces fragments of the original packet and sends them to trick the firewall in this type of attack. In order to prevent this type of attack firewall discards all packets that use the TCP protocol and is fragmented. Incoming TCP packets are only allowed via Dynamic Packet Filters if they are answers to outgoing TCP packets.

DDoS attacks have no simple remedy because there are several attack strategies that can exploit various faults in network infrastructure. Scrubbing services are offered by several cybersecurity businesses, which divert incoming traffic away from your network and distinguish legitimate access attempts from DDoS traffic. This legal traffic is then redirected to your network, allowing you to get back to operation as usual.

2. Insider Attacks

Even though they aren't the most likely of attacks, insiders pose a threat to firewalls. This common firewall vulnerability is perpetrated by someone who has been given authority to breach your perimeter firewall. Access to your internal systems should have been granted to that person as well. A proper network segmentation configuration strategy can help to mitigate employee hazards.

3. Outdated Firewall Software

A firewall software has weaknesses that attackers can exploit, just like any other piece of software. When firewall vendors find these issues, they usually work rapidly to develop a patch to fix the problem. Some security teams, on the other hand, are extremely busy, and it's easy to get behind on firewall updates. Until the patch is deployed to firewall firmware, the vulnerability will remain unpatched, waiting to be exposed by a random intruder. Patching procedures that aren't up to par can leave businesses vulnerable to firewall attacks.

Establishing and adhering to a disciplined patch management schedule is the most effective answer to this problem. The security team should check for all firewall software security upgrades and make sure to apply them, according to this plan.

4. Failure to Activate Controls

One of the most common firewall issues that businesses face is controls that aren't properly activated. Anti-spoofing tools, for example, are an important aspect of your managed security system since they prevent malware, spam, and other fake traffic from entering your network. A distributed denial-of-service attack will almost surely occur if you don't enable this control.

5. Lack of Documentation

If any of your security professionals resigns unexpectedly or is unavailable for an extended period of time, keeping application documentation and rule decryptions on hand might help your firm avoid security breaches. Work is less likely to be duplicated with proper documentation, providing employees more time to focus on higher-level activities.

6. Basic Inspection Protocols

Next-generation firewalls provide a deep packet inspection feature to evaluate the contents of a network packet before permitting or denying it passage to or from a system. Less complicated firewalls may merely examine the data packet's origin and destination before permitting or denying it, information that an attacker may easily spoof to fool the firewall.

The best solution for this issue is to use a firewall that can perform deep packet inspection on data packets in order to detect and reject known malware.

7. Improper Configuration

Even if your network has a firewall and all of the latest vulnerability updates installed, the firewall's configuration settings may conflict, causing problems. This can cause a drop in network performance in some cases, while in others, a firewall may fail to provide appropriate protection. According to Gartner data, misconfiguration, not weaknesses, is the source of 95% of all firewall breaches. This indicates that a firewall's parameters are inaccurate due to human error or a lack of investigation. Indeed, Gartner estimated in 2016 that by 2020, this ratio will have risen to 99 percent. Using a weak password is a common configuration mistake. Due to character constraints, modern passwords can be difficult to remember. For the sake of convenience, some employees may utilize simple passwords or factory default settings. If this happens on your firewall, you're more vulnerable to account theft than you would otherwise be. A poorly constructed firewall makes things easier for attackers while squandering your time, money, and effort.

What are Types of Firewall Attacks?

Malicious intruders use literally hundreds of methods and tools when they attempt to compromise PCs. Some of the most prevalent external firewall attacks are as follows:

1. Network traffic flood The concept underlying network traffic deluge attacks is that too much of a positive thing can be detrimental. Instead of attempting to identify a computer's vulnerabilities, special programs called flooders transmit hundreds to tens of thousands of legitimate network packets to a single PC in an attempt to overwhelm its response capacity. This process frequently results in a Denial of Service (DoS) attack, but flooders have circumvented firewalls and assumed control of victim PCs.

2. Port scan: To assault a PC, an intruder must identify which TCP or UDP ports (and thus services and programs) are accessible. Each program that connects to the Internet or accepts connections from the Internet is assigned an IP port number (0 to 65536) between 0 and 65536. Typically, port numbers signify a specific form of service. For instance, Internet email typically utilizes port 25 for SMTP and port 110 for POP. When downloading files from an FTP site, your computer uses port 20 or port 21. Intruders frequently scan victim computers (connect to multiple ports) to determine which ports are active. After identifying the open ports, intruders (or their malicious software) limit future attacks to a specific port type. As it is unusual for a remote computer to connect to more than a few ports at once, firewalls should detect this activity.

3. Fragmentation attacks: Intruders are able to fragment IP packets and reconstitute them at the destination computer. Intruders have learned to manipulate reassembly in order to bypass computer security defenses with malicious traffic and programs.

4. IP spoofing: All firewalls filter network traffic based on IP addresses (for instance, 192.168.10.2). Typically, the computers behind the firewall are permitted to conduct more operations than the untrusted computers on the network's perimeter. Intruders can send their traffic with IP addresses that make it appear as if the transmission originated from within the firewall, thereby gaining greater access than would normally be permitted.

5. Malformed network packets: Most computers are overly courteous. If someone sends them an improperly formatted network packet, they will either attempt to reassemble it (often allowing something to bypass a firewall or malware analyzer) or reject it and wait for a retransmission. Anyone who possesses a Windows PC is aware that installing software can take a long time. Intruders who employ this type of attack are either attempting to circumvent a specific security measure or launching a denial-of-service attack by causing the PC to wait for a very long time and disregard legitimate transmissions.

Some of these assaults are technically sophisticated and necessitate the expertise of an experienced intruder. Worms and Trojan horses are increasingly automating external attacks that trawl the Internet for vulnerable machines. Often, compromised machines serve as a staging ground for additional assaults against new machines. Security experts expect both manual and automated decryption to rise for the next few years until the Internet becomes more secure.

How to do Firewall Threat Protection?

As cybercriminals become more sophisticated, the attacks they launch against your company will get more inventive and do greater damage. This means your first line of technical defense must be of the best possible quality and ready to safeguard your network from incoming attacks.

A firewall's job isn't done after it's installed; it needs to be supplemented with specific firewall policies and procedures that are owned and maintained by a professional. Your firewall is more likely to fail if you don't take this extra step, leaving your network vulnerable to viruses, hackers, and other harmful traffic.

Only an expert would know where to begin when configuring a firewall. Unfortunately, quite often, the administrator of firewall configuration fails to select the right access control settings from the list.

Misconfigurations are almost always the result of human error, and it's easy to see why. In network device configuration, for example, 'eq' ('equal to') enables access to a single, specified port, whereas 'neq' ('not equal to') allows access to any service. A single 'n' error can turn an entire traffic stream from extremely niche to extremely broad.

An administrator can also configure a firewall exactly as suggested and still have it fail. For example, if a systems audit isn't performed to discover specific holes or cyber risks, your company may unintentionally ignore a substantial risk or a certain firewall setting. An audit may also reveal the necessity for unique architecture rather than a one-size-fits-all solution.

Before we go over the concepts for improving firewall threat prevention, let's have a look at the most common causes of firewall failure:

• Insufficient Hardware Resource: The growing number of devices and applications used in businesses today is continuously pushing network performance to its limits. You must avoid having your security solution become a bottleneck. Heavy congestion or bottlenecking may occur if your hardware isn't powerful enough to handle network demand. When the firewall is overloaded, you'll notice limited throughput, excessive CPU consumption, and application slowdown. Furthermore, application performance may be severely harmed. Also, in the worst-case scenario, the firewall could break. To address these difficulties, you may wish to consider upgrading your hardware, or you may be compelled to disable some firewall functionality, allowing attackers to exploit vulnerabilities. Intrusion Prevention Systems (IPS), which evaluate network traffic flows to detect and prevent vulnerabilities, and application control are two of the resource-intensive capabilities.

• Incompatibility: A firewall might become incompatible with new technologies if it isn't updated and maintained on a regular basis. As a result, they are unable to defend against sophisticated threats. So, a firewall should be upgraded regularly and make sure it's up to date and running. After all, it's much easier to prevent risk than recover from a catastrophe.

• Firewall policy that is either missing or incorrect: A firewall policy outlines how it manages incoming and outgoing packets on information security policies. It's possible that a policy was poorly written or simply did not exist. Administrators may mix and match different rules, resulting in a very broad policy setup that leaves their network permanently vulnerable. As a result, the firewall fails. Make sure you thoroughly specify the network regulations and adhere to the principle of least privilege (POLP), which means just granting the user or service the privileges they require to function normally.

• External Asset Failure: Most firewalls work in tandem with a larger IT infrastructure and rely on each wheel to work properly. For example, if a malevolent actor acquired access to the ISP, they could most likely breach the entire firewall. It is strongly recommended to schedule an IT audit, which involves a full and holistic examination to identify areas where a hack could have a domino effect.

• Software Vulnerabilities: It is critical to keep firewall software up to date. Firewall software can sometimes have hard-to-find flaws, such as encryption keys and passwords hard-coded into the software. Ensure that your firewall, as well as any integrated software, is patched and updated.

Even while misconfiguration is the most prevalent reason for firewall failure, there are many other factors to consider, including how well it connects with your IT infrastructure, how advanced it is, and the rate at which cyber threats evolve. The success of your firewall and cybersecurity is determined by a number of aspects and conditions that differ greatly from one company to the next.

How to Improve Your Firewall Security?

Some principles for defending against firewall evasion are listed below:

• The firewall setting should be done in such a way that the IP address of an invader is filtered out.

• Configure the firewall ruleset to prohibit all traffic and only allow access to the services that are necessary.

• Create a unique user IP to operate the firewall services if possible. Rather than using the root ID to launch the services.

• Set up a remote Syslog server and take precautions to keep it safe from unwanted users.

• Firewall logs are checked at regular intervals, and any suspicious log entries are investigated.

• By default, all FTP connections to and from the network are disabled.

• Monitor user access to firewalls and regulate who can modify the firewall configuration

• Catalog and review all incoming and outgoing traffic allowed through the firewall

• Run periodic risk queries to identify high-risk firewall rules

• Specify the source/destination IP addresses as well as the ports

• Document and notify the security policy administrator about firewall modifications

• Restrict physical access to the firewall

• Back up the firewall ruleset and configuration files on a regular basis

• Schedule regular firewall security audits

• On the external interface, anti-spoofing restrictions should be enabled to prevent denial of service and associated attacks.

To sum up, to improve your firewall security you should document your network infrastructure, alter firewall and security architecture, fine-tune your firewall, security hardening, standards, policies, change management, etc.

What is a Firewall Risk Assessment?

A firewall risk assessment is a thorough examination of the architecture and configuration of a firewall that has been installed to safeguard your data, applications, systems, and overall business operations.

The evaluation will assist companies in improving and maintaining the various levels of their network to prevent hackers from harming the company's operations and stealing information. It is helpful for ensuring that your firewalls are properly protecting essential business information and data. Firewall risk assessment is also a fundamental need in international standards and laws such as PCI and HIPAA for some businesses.

Organizations are putting more emphasis on compliance and auditing of their cybersecurity policies and cybersecurity controls as a result of additional regulations and standards pertaining to information security, such as the Payment Card Industry Data Security Standard (PCI-DSS), the General Data Protection Regulation (GDPR), the Health Insurance Portability and Accountability Act (HIPAA), and ISO 27001.

Even if your corporation is not required to follow industry or government regulations or cybersecurity standards, it stands to reason to carry out a comprehensive audit of your firewalls on a constant schedule.

Firewall audits guarantee that your firewall configurations and rules comply with external regulations as well as your internal cybersecurity policy. But even so, these audits can also play a significant role in risk reduction.

A manual cybersecurity audit is nearly impossible to perform in today's multi-vendor network environments, which typically include a large number of firewalls running thousands of firewall rules.

Furthermore, because the documentation of current rules and the history of their revisions isn't always up to date, manually finding, organizing, and reviewing all of the firewall rules to establish how compliant you are takes time and resources. This puts a strain on your information security team.

Auditing becomes increasingly challenging as networks get more complex. And manual procedures are just unable to keep up. As a result, you should automate the process of auditing your firewalls because it's critical to audit for compliance on a regular basis, not only at a specific period.

Weak or out-of-date firewall rules could expose superfluous service information on the servers hosting business applications, allowing an attacker to exploit the vulnerability after a compromise.

You must first do a risk assessment to determine the level of protection required, and then establish your own policies for managing those risks. It's vital that you understand how to use firewall controls because they safeguard your firm from hazards related to connections and networks while also lowering risks. You must document the control's objective, how it will be implemented, and what advantages it will give in terms of risk reduction.

The following important areas are examined during the firewall security assessment:

1. Change Management: To ensure that the firewall modifications are correctly implemented and traced, you'll need a strong change management strategy.
   • Are the changes being implemented by authorized personnel?
   • Are you putting the changes to the test?
   • Are the requested changes receiving the necessary approvals?
   • Are you documenting modifications in accordance with regulatory standards and/or internal policies? Each rule should have a comment that includes the request's change ID and the name/initials of the person who made the change.
   • Is there a time limit for the change?
2. Physical and System Security: To protect against cyberattacks, you must also be confident in the physical and software security of each firewall. In this way:
   • Make sure you've installed all of the necessary vendor fixes and updates.
   • Verify that the operating system passes standard hardening tests.
   • Examine the device administration policies and processes.
   • Make that the firewall and management servers are physically secure and accessible only to authorized personnel.
   • Make sure you have a current list of people who have permission to access the firewall server rooms.
3. Enhance and clean up the rule base: By removing firewall clutter and improving the rule base, you may greatly boost IT efficiency as well as the firewall's performance. Furthermore, improving firewall rules can drastically save a lot of unnecessary overhead in the audit process. As a result, you should do the following tasks:
   • Determine which rules are disabled or unneeded and should be eliminated.
   • Delete or disable any rules and objects that are no longer in use or have expired.
   • Remove unnecessary rules.
   • Examine the performance and effectiveness of firewall rules in terms of their order.
   • Find the duplicate rules and combine them into a single rule.
   • Enforce naming conventions for objects.
   • Keep track of changes to rules, objects, and policies for future reference.
   • By comparing actual policy usage to firewall logs, you may find and fix overly permissive policies.
   • Analyze VPN parameters to find underutilized and unattached users and groups, as well as expired and about to expire users and groups.
   • Delete any connections that aren't in use, including source/destination/service routes.
4. Conduct a risk assessment and address any issues that arise: A thorough risk assessment will reveal any rules that may be in jeopardy and confirm that they are compliant with applicable standards, legislation, and internal policies. Make a list of all the regulations that could be jeopardized based on industry standards and best practices, and rank them in order of severity. Although the rules that may be at risk for each firm vary depending on its network and the level of acceptable risk, there are a number of frameworks and standards that can serve as a suitable starting point. Make certain to:
   • Verify that all repair activities and rule modifications were completed correctly.
   • Keep track of your cleanup efforts and keep a record of them.
   • Document and designate an action plan for resolving risks and compliance exceptions discovered during the risk assessment. Here are some things to keep an eye out for and verify:
   • Do any firewall rules allow direct traffic from the Internet (not the DMZ) to your local network?
   • Do any firewall rules permit traffic from the Internet to sensitive servers or devices?
   • Are there any firewall rules that go against your security policy?
   • Do any firewall rules allow dangerous services to enter your internal network from your demilitarized zone (DMZ)?
   • Are there any firewall rules that allow dangerous services from the Internet to come in?
5. Continuous Audit: You'll need to take the following steps to maintain ongoing compliance:
   • Automated analysis and reporting are being used to replace human processes that are prone to errors.
   • Assuring that you have a solid firewall-change workflow in place to ensure long-term compliance.
   • Have a system in place to notify you of critical events or actions, such as modifications to particular regulations or the discovery of new, high-severity risks in your policy.
   • Creating a process for auditing the firewalls on a regular basis.
   • Creating a thorough audit trail of all firewall administration actions by properly documenting your audit procedures.

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