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Firewall Security Audit: Why and how to do it right? 

What is a Firewall?

A Firewall points to a network security device that observes incoming and outgoing network traffic. It typically determines whether to allow or block specific traffic based on a defined set of security rules. It intends to establish a barricade between your internal network and incoming traffic from external sources (such as the internet). The goal is to block malicious traffic like viruses and hackers. Enterprises can implement a firewall either in hardware or software or a combination of both. The focus lies in preventing unauthorized parties from accessing enterprise private networks.

Different types of Firewalls

Packet filtering firewall

Packet-filtering firewalls, the most common type, inspect packets and deny them from passing through if they don’t correspond to an established security ruleset. This type of firewall inspects the packet’s source and destination IP addresses. If the incoming packets match the allowed ruleset, permission gets granted to enter the network.
Packet-filtering firewalls are of two categories: stateful and stateless. Stateless firewalls inspect packets independently and lack context, making them effortless targets for hackers. Contrastingly, stateful firewalls retain details about previous packets and are considered much safer.

Stateful inspection firewall

Stateful inspection firewalls keep track of network connections. It constantly analyses the whole context of traffic and data packets that seek network entrance. It combines some of the traits of circuit-level gateways and packet filtering firewalls. Hence, it drives more security and efficiency in contrast with the other two types.

Proxy firewall

Proxy firewall filters network traffic at the application level. Unlike basic firewalls, the proxy acts as a mediator between two end systems. The client should send a request to the firewall, where it gets assessed against a set of security rules and then qualified or blocked. Notably, proxy firewalls scan traffic for layer 7 protocols such as HTTP and FTP and use both.

Unified threat management (UTM) firewall

A UTM device typically mix in a loosely coupled way, the functions of a stateful inspection firewall with intrusion prevention and antivirus. It may come inclusive of additional services, often cloud management. UTMs focus on simplicity and comfort of use.

Next-generation firewall (NGFW)

It combines traditional firewall technology like packet filtering and stateful inspection with additional functionalities. It can be encrypted traffic inspection, intrusion prevention systems, Anti-virus, application awareness and control to see and block risky apps, and more. Most notably, it incorporates deep packet inspection (DPI). While basic firewalls only scan packet headers, deep packet inspection examines the data within the packet itself. It helps users easily spot, classify, and block those packets containing malicious information.

What is a Firewall Security Audit?

A firewall Security audit is a process that delivers visibility into an enterprise firewall access and connections. Because of additional regulations about information security, including Payment Card Industry Data Security Standard (PCI-DSS), the General Data Protection Regulation (GDPR), Sarbanes-Oxley (SOX), the Health Insurance Portability and Accountability Act (HIPAA), organizations are putting more emphasis on compliance as well as the auditing of their cybersecurity policies and controls.

Even if your company need not comply with industry regulations, it still makes sense to conduct firewall audits regularly. These audits ensure that your configurations and rules stick to the requirements of external regulations and your internal Information security policy. However, these audits play an essential role in reducing risk to the extremity. Also, it helps improve firewall performance by optimizing the firewall rule base. Besides compliance necessities, auditing firewall security improves the enterprise security capability of detecting security posture weaknesses.

Significance of Firewall Security Audit

The prime intention of implementing firewall protection is to get rid of malicious traffic from your enterprise network. They use signature patterns to find malicious payloads and rule patterns for detecting unauthorized traffic. These malicious payloads could evolve rapidly, and hence, updating signatures is a vital necessity.

Also, when considering firewall security, managing specific rule sets is another significant thing. A small error in rule management could be fatal for the whole network. Malicious actors and hackers are also constantly evolving to new trends and looking for the minute flaw in security controls. Therefore, firewall security testing and audits prove vital considering enterprise network security.

Steps to perform a Firewall Security Audit

It is important to note that the firewall doesn’t manage by itself. So regular security audits become a vital element while considering firewall maintenance and security. Here we describe key information the checklist of best practices followed while conducting audits for firewall security.

  • Gather key information

          Your firewall audit won’t probably bear the expected outcome unless you have absolute visibility into the network. It should completely cover hardware, software, policies, procedures, and risks. Here we enlist all the critical information you need to figure before the audit process.

  • Copies of relevant security policies and procedures
  • A precise diagram of your current network and firewall topologies
  • Past audit reports/documents, including firewall rule sets and policy revisions
  • Overview of Virtual Private Networks (VPNs) and Internet Service Providers (ISPs)
  • Information about firewall vendor, version of OS, default configuration and latest patches performed
  • Knowledge of critical servers and data repositories present in the network
  • All system data flows and interconnections

Once you get the complete information, document, store and consolidate it in a way that allows smooth communication with IT stakeholders.

  • Review the firewall change management process

Firewall changes/amendments could be executed and tracked accurately through a solid change management process. Two of the most common issues related to the change management process are – Inadequate documentation and verification of changes.

The former connects to questions like;
-Why do enterprise firewalls require a change?
-Who authorizes the change?
The latter issue deals with not properly validating those changes in the network.
While reviewing the rule-based change management process, these are some critical questions to consider.

  • Are changes spanning through proper approvals?
  • Are changes getting implemented by authorized personnel?
  • Is there a testing practice for the changes?
  • Are the changes documented and stored adhering to various requirements of regulatory
  • bodies and policies?
  • Whether or not have a controlled and formal process to request, review, endorse and deploy firewall changes?
  • Audit firewall Operating System and physical security

Find out if you can negate cyber security issues, both from your firewalls physical and software security side.

  • Ensure there is controlled access for firewall and management servers.
  • Make sure there is a proper list of personnel authorized to access firewall server rooms.
  • Evaluate procedures and policies implemented for device administration.
  • Verify whether proper vendor patches and updates are performed.
  • Assess whether the OS passes through solid hardening checklists.
  • Check and maintain the list of authorized personnel with access to server control rooms.
  • Clean up and improve the rule base (also called a policy)

The next thing to do in firewall security testing is to remove clutters and optimize the rule sets. Improving firewall rules can vanish the overheads in the audit process. Also, it is a way of hiking firewall performance and improving productivity. So, make sure to: –

  • Remove unnecessary or irrelevant rules.
  • Search, identify, and disable unused rules and expired objects.
  • Assess the order of firewall rules for their performance and effectiveness.
  • Enforce object-naming conventions.
  • Delete the unused connections, including source/destination/service routes, that you’re not using.
  • Identify identical rules and merge them into one.
  • Detect permissive rules by evaluating policy usage against firewall logs.
  • Analyze VPN parameters to uncover unused users and groups, unattached users and groups, expired users, and groups, as well as users about to expire.
  • Perform risk assessments and remediate issues

A detailed and thorough risk assessment help discover risky rules. Similarly, it ensures that these rules adhere to firewall security standards and internal policies. Use the audit best practices to uncover risky rule sets and prioritize them based on severity. The process is subject to every enterprise concerning their network and criteria for acceptable risk. Following are the things to validate in the risk assessment and remediation stage of firewall audit.

  • Whether any firewall rules violate the existing security policy?
  • Does the firewall allow outward-facing services to your internal network?
  • Does the firewall allow risky services inbound from the internet?
  • Do the current firewall rules allow outbound services to the internet?
  • Do the current firewall rules impact corporate policy?

Also, inspect firewall rules and configuration in line with regulatory standard requirements. Make sure to: –

  • There are effective remediation measures for the compliance exceptions related to identified risks.
  • Verify remediation efforts and corresponding rule changes.
  • Trace and document that you have completed all remediation efforts.
  • Conduct continuous audits

Once the enterprise succeeds with the initial firewall security audit, they must ensure continued compliance with the following directions: –

  • Establish an ongoing process that audits the firewall security.
  • Properly document and store all audit procedures and policies.
  • Re repeated manual tasks to automated analysis and reporting.
  • Assure there is a robust firewall change process in place.
  • Ensure there is a prompt alert system in place for vital events and activities.

Organizations can get the full benefits of firewall security only by routine and continued audit services. Firewalls are the access gates to your organization and should be the foremost consideration to security.

Summing Up

By choosing security testing companies, enterprises not only benefit from firewall protection, but also in building an upright security posture. Amidst rising security concerns and compliance requirements, a security testing company proves to be the perfect companion for enterprises security. Digital issues would keep popping up with time, and regulations might become more stringent. Having a security advisory partner by your side can help enterprises rub off the security hassles. Moreover, being steady and uncompromisable with security is a vote of trust that drives productivity and user confidence to the peak.