What is a Secure Web Gateway?

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A secure web gateway is a web security service that is delivered on-premise or via the cloud for the purpose of checking and filtering unauthorized traffic from accessing a network. These gateways have revolutionized the way we implement unified security at remote sites and on the web, regardless of the number of users involved. In addition to delivering security, secure web gateways help the users protect themselves from data breaches and ensure compliance with increasingly stringent regulations in this domain. All of this warrants a deeper look under the hood of these essential security tools and a contrastive comparison with seemingly similar solutions in the security market. 

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What’s the mission of a Secure Web Gateway? 

Secure web gateways (SWGs) employ the architecture that allows them to perform their primary task: keeping your network clean by filtering out the undesired segments of the internet traffic and keeping dangerous websites at bay. These gateways put data in the focus of their attention, helping them zero in on threats before they even penetrate your virtual perimeter.

Speaking of data, SWGs see it as a chief infection vector that hides in the wings of malware as its carrier. To filter out malicious data, secure gateways will combine security barriers such as URL and network filtering and malware elimination, malicious code detection, application controls, and anti-data leakage features. These security layers can help you protect sensitive data from theft, including but not limited to social security numbers, medical records, credit card information, etc.

In larger organizations, secure web gateways play an additional role of a content moderator for groups of users. As corporate assets need to be carefully balanced against both accessibility and security, secure web gateways bring order to the chaos of people, sites, applications, sensitive data, and work processes that need to be protected. All of these also need to be made accessible to both internal and authorized stakeholders, with threat actors being intercepted, checked, and either let in or quarantined.

How does a Secure Web Gateway work? 

Secure web gateways operate as web proxies that can both stop web traffic and serve as proxies for it. All traffic gets inspected in sequence as part of security controls and in line with applicable security policies. Techniques featured in the secure gateway package can include anti-malware checks, web filtering, sandboxing, web isolation, data theft measures, etc. Sometimes, these go together with machine learning processes and cloud access security broker (CASB) checks.

All of these checks are performed in line with the security policies that guide the operation of a secure web gateway. Once defined, these will determine how a secure web gateway implements threat prevention, how security rules are applied for an individual or a group, how a particular type of content is managed (accessible or prevented from loading), and other considerations. These policies need to be implemented flexibly and with scaling in mind to meet the needs of increasingly sophisticated threats. This also includes frequent updates and preparation for tackling zero-day threats. 

The role of URL Filtering 

URL filtering describes the technology used to sift through all incoming network traffic and check it against the information in databases to limit access to dangerous sites such as those with malware or phishing code. As a rule, these databases contain information on what is allowed or prohibited, such as social media platforms, gambling and adult sites, e-stores, etc.

The URL filtering engine often plays the role of the first line of defense in a secure web gateway. It prevents access to undesirable URLs and posits itself as a barrier against evolving threats. The latter is done by identifying and learning from dangerous URLs that correspond with what is found in the database of malicious sites.

Next in the defensive perimeter line is sandboxing – it is a cybersecurity technique in which a potentially dangerous code is placed in an isolated environment to be observed and analyzed. This is done by emulating standard web environments that may be found with regular users. Based on this, sandboxing can give you a real-time shield that prevents code-based attacks on valuable assets.

Browser/web isolation is yet another security layer in a secure web gateway. It involves containing browsing activity in an isolated computer- or server-based environment such as a virtual machine. In this manner, the users are protected from malicious server codes, data theft, and malware in general.

Are secure web gateways similar to firewalls? 

There is an overlap in terms of the functionality of secure web gateways and firewalls, to the point of some people mistaking one for another. Yet, these are dissimilar in several key aspects.

First of all, a secure web gateway is a proxy. This means that it can stop or emulate traffic. This feature allows the gateways to cut short more advanced threat vectors originating on the web. Firewalls, on the other hand, are generally less sophisticated and deliver security at a level of a data packet that gets checked for malware. They are usually unable to block traffic or check objects or applications for their threat levels.

Secure web gateways operate at the level of an application and, as such, can deny access to the sites and apps they deem potentially dangerous. They have blacklists and whitelists with keywords and stored connections and are capable of restricting the functionality of regular operations such as data download management.

Finally, secure web gateways are used to create and implement security rules and policies for various users which is not the case with firewalls.

What about cloud access security brokers? 

Just like firewalls, cloud access security brokers (CASBs) are yet another piece of technology often confused with secure web gateways. Actually, these two complement each other more than overlap, but basic similarities are shared. Yet, in general, secure web gateways are more focused on keeping your traffic clean and logging everything that happens with it while CASBs provide greater visibility into the general security status of a system. In addition, CASBs are more focused on what happens with your applications and exercise greater control over them compared with SWGs. 


Secure web gateways have managed to firmly integrate themselves with the modern-day security landscape, primarily on the account of the increased public interest in everything cloud-based. Changed perception of what these systems can do and the general maturing of the technologies that make them up have broken the long-lasting spell of the antivirus-firewall combo as the backbone of security of a bygone era. With the meteoric rise in the volume of web traffic and the number of connected devices, secure web gateways have proven themselves to be capable of plugging the majority of newly arisen security gaps and remained a force to be reckoned with in a web security world. 

Sead Fadilpašić

Sead is a seasoned freelance journalist based in Sarajevo, Bosnia and Herzegovina. He writes about IT (cloud, IoT, 5G, VPN) and cybersecurity (ransomware, data breaches, laws and regulations). In his career, spanning more than a decade, he’s written for numerous media outlets, including Al Jazeera Balkans. He’s also held several modules on content writing for Represent Communications.