What Is SSL Inspection?

With malware attacks on the rise, the need to protect data is felt more than ever. While there might be many options in the market, SSL inspection is a security feature that detects an online threat in encrypted SSL traffic.

Sitting between the user and the website, SSL inspection checks web traffic to detect any malicious activity. As cyber criminals pick up the pace with hacking, it is equally important to counteract their actions through updated checkups.

An SSL inspection can give your organization’s data the protection it demands. Here, we’ll talk you through the importance of SSL interception and give a brief outlook on its merits and demerits. Read along to find out more about the entire SSL inspection process.

What Is SSL Inspection?

SSL stands for Secure Sockets Layer, based on encryption to protect users’ information on a webpage. SSL inspection involves decrypting this confidential information to inspect any malware hidden inside. By monitoring the web traffic, SSL inspection runs as a security checkpoint between the client and the server to filter data before it reaches the next stage.

Also known as HTTPS inspection or TLS interception, this process works to improve website security. Since malicious content appears as encrypted traffic in an SSL, inspecting the traffic can help block such malware. Thus, the SSL inspection works as a middleman to mitigate cybercrime risks in communication channels over the internet.

How Does SSL Inspection Check HTTPS Traffic?

SSL inspection uses an interceptor that checks all sensitive data passing between the client and the server before forwarding it to its destination. The interception device acts as a middleman to decrypt all data, check it for any malware, and then re-encrypt it.

Generally, the SSL inspection software may use an anti-virus, next-generation firewall, IDPs, and IPS to detect any malware entering or leaving the system.

With all the traffic passing through the SSL connection, there is hardly any chance of malicious activity escaping the inspector. And the good part? HTTPS interception works to inspect HTTPS traffic going either way, i.e., browser to the server and server to the browser. Here’s a brief overview of the entire process.

  1. As HTTPS connections are established between a server and the browser, the traffic is intercepted and decrypted.
  2. The interception device scans the data through anti-virus scanning and blocks malicious content.
  3. The remaining data is re-encrypted in the original format by the interceptor and forwarded to the predestined webserver.

Methods Of SSL Inspection

SSL interception can use several methods, each with its configuration and impact. Let’s have a look at how these enable SSL inspection.

TAP (Terminal Access Point) Mode

For offline analysis, TAP works best to copy all network traffic on a hardware device. It might be costly to ensure all data is copied without any loss or tampering. TAP can analyze the data traffic by acting as a passive security probe.

Next-Generation Firewall

NGFWs monitor SSL-encrypted internet communication and detect a fraction of mal-activity. Despite limited security performance, NGFWs can utilize deep SSL inspection or intrusion prevention systems to block sophisticated attacks.


Proxies work by establishing a full-fledged HTTPS connection between the client and the server. These connections allow heavy traffic flow with assembling, scanning, and threat detection of real data. Proxies utilize sandbox and data loss protection technology to classify information.

Importance Of HTTPS Inspection

As explained earlier, SSL or TLS is an encrypted communication method on the internet that works to keep data preserved in undecipherable algorithms. SSL certificates are useful to keep passwords and personal information secure.

However, they might also hide in viruses, spyware, and malware due to third-party intervention. As malware gets encrypted, it often goes unnoticed by security channels, thus leading to unchecked exploitation.

To curb such cybercrimes, HTTPS inspection allows the user to perform web filtering, email filtering, and anti-virus scans for data safety. It de-crypts all SSL traffic to identify any unusual activity between a user and browser in the HTTPS traffic flow.

It can prevent malware from reaching your systems and accessing confidential information. This is particularly useful for small businesses and corporate organizations to prevent data security breaches.

Merits Of SSL Inspection

Once we’ve established what is SSL inspection and its works, here’s a deeper insight into a few other benefits.

Blocks Malware

HTTPS inspection works one step ahead of the hacker to detect any encrypted malicious content. It links cyber security software to test sandbox content and compares it with known malware.

In simpler terms, the interceptor scans the data before you download a malicious file or click on an infected link. Through such protective mechanisms, SSL or HTTPS inspection prevents hackers from sneaking past defenses.

Monitors Traffic Flow

SSL inspection filters out URLs, IPs, or suspicious network systems by checking network patterns and traffic flow. It can help identify the data flow out of an organization, whether accidentally or intentionally.

On top of that, it keeps track of the exfiltration and uploading of data. By looking at known patterns, TLS inspection can identify potential risks before they come into action.

Better Security Policies

The corporate world is highly susceptible to data breaches and malicious activity. However, small businesses are no less targeted nowadays due to their inexperience and lack of security.

SSL interception enables a multi-defense layer in your working environments. Since HTTPS inspection protocol can be implemented quickly, it offers a higher chance of ensuring security and routing policies in an organization.

Demerits Of SSL Inspection

Like any other software, HTTPS inspection has disadvantages that cannot go unnoticed. Poorly executed SSL/TLS inspection can do more harm than good, so it’s crucial to realize the demerits before jumping into it.

Increased Vulnerabilities

Web browsers are constantly updated to bypass malware, but inspection software lag behind in their updates. The SSL protocol is constantly undergoing improvements, so a failure to install the latest and most secure version could result in exposed vulnerabilities.

Moreover, SSL/TLS inspection creates two connections, so the complete success of the process comes down to a single focal point which raises serious concerns about its security.

Post-Inspection Security

After the data is decrypted and inspected, the interceptor re-encrypts it before sending it to the server. Obsolete cryptographic standards make post-inspection encryption weaker and less secure, thus being more susceptible to exploitation.

Unless SSL interception is implemented correctly, it poses many security threats because the middlebox usually comes with severe vulnerabilities.

Compromised SSL Certificate

The primary risk associated with SSL/TLS inspection is the whitewashing of original SSL certificates. After re-encryption, there is no foolproof way to check if the SSL-encrypted traffic comes from a trusted source.

Cybercriminals can even fake a certification because the middlebox doesn’t verify certificate chains before forwarding the data. Without proper SSL certificate validation, there is a greater risk of criminal attack from a different route.

No Privacy

With SSL inspection, HTTPS encryption loses its purpose. As all data is decrypted, there is no privacy towards personal information like passwords, health records, credit card details, etc. Worse, if hackers gain access to decrypted traffic, they could get their hands on all sensitive information, opening doors to all kinds of attacks.

SSL Offloading

SSL-related functions like encryption or decryption strain your browser and slow down its efficiency. These can be catered to through SSL offloading- a procedure that relieves a web browser from its processing burden.

Simply put, offloading benefits the server with better performance to handle other task demands. SSL offloading is quite similar to SSL interception. It comes in two options:

SSL Termination

In this process, the incoming data connects to an SSL terminator or load balancer through a secure connection. However, the second connection between the SSL terminator and the server is insecure because it passes the data in plaintext.

This can raise serious security concerns as hackers can access your data fully if they’ve infiltrated the system. SSL termination works best to increase the decryption speed. It can be considered on platforms like YouTube, Wikipedia, etc., to increase the loading speed.

SSL Bridging

As a better option, SSL bridging uses SSL certification and re-encrypts all data before sending it to the application server. It is a secure connection and works best for websites with sensitive information like credit card details, tax records, health forms, etc.

Similar to SSL inspection, it decrypts incoming data to check for any malware or spyware and then re-encrypts it to forward it to the application server. However, SSL bridging may be more costly because it utilizes many resources.

Alternatives to TLS Inspection (Transport Layer Security)

If you’re still doubtful about SSL/TLS inspection, here are a few other methods to combat hidden malware in internet traffic. Some measures that might prove helpful include firewalls that can inspect security certifications without an interceptor.

Such firewalls don’t bypass the encryption code, so data remains safe from potential vulnerabilities. DNS filtering and browser isolation ensure secure IP connections and keep all activity confined to a single server.

You can also use HTTPS categorization to filter URLs without SSL/TLS inspection. Some basic antivirus software, email filtering, and deep inspection in a firewall can also play a vital role in securing internet connections.

Furthermore, companies can safeguard their networks by reinforcing security policies and educating their employees. Never download unapproved software, click on a malicious link or trust a third-party agent.

Final Thoughts

Although one might argue that SSL encryption keeps data protected and safe against a third party, malicious agents taking refuge in SSL traffic are on the rise. SSL/TLS inspection is important in keeping a security check on web HTTPS traffic. With an efficient inspection system, you can prevent malcontent from sneaking under your nose.

TLS inspection, or transport layer security inspection, is a debatable concept due to the questionable security of the middlebox. So, before you decide on a move, we’d recommend considering the nature and scale of your business paired up with other protective software.

Derik Belair

As President and CEO, Derik leads the vision, strategy and growth of Augmentt. Prior to founding Augmentt, Derik was the Vice President at SolarWinds, leading the digital marketing strategy for SolarWinds’ Cloud division. Derik has been working in the channel for over 20 years, starting his career as a channel sales rep at Corel Corp. and eventually becoming the first employee at N-able Technologies in April of 2000.
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