How SSL certificates can help prevent Man-in-the-Middle attacks

In this increasingly dangerous digital environment, experts and ordinary web users alike must protect against vulnerabilities brought on by unsecured WiFi networks, poorly protected login credentials, and more. New threats are always lurking, but thankfully, some tried-and-trusted solutions can provide a powerful baseline of protection.

Unfortunately, some of the most dangerous attacks are also the least recognized and the most complicated to combat. Man-in-the-middle (MITM) attacks pose a threat because these cyberattacks are difficult to detect and, as a result, difficult to prevent. No single strategy will guarantee success, but a layered approach can prove effective—especially if this includes the use of SSL/TLS certificates.

What is a man-in-the-middle attack?

Man-in-the-middle attacks occur when threat actors intercept communication between two unsuspecting parties. Not only do these malicious parties eavesdrop, they attempt to take control of the conversations or interactions, often modifying information to trick one of the parties into sharing sensitive data. Done successfully (at least, from the attacker's perspective), the victims will never know they've been targeted and will never realize they've divulged important information.

This process can look dramatically different depending on what the threat actors hope to accomplish and how they aim to obscure their approach. Generally, however, positioning between two targeted parties is typically achieved by exploiting existing vulnerabilities. Unsecured WiFi presents one of the biggest opportunities for malicious parties to launch such attacks, but often, bad actors also make the most of poor encryption and other weaknesses. 

The role of SSL certificates in MITM attack prevention

Secure Sockets Layer (SSL) / Transport Layer Security (TLS) certificates can play a powerful role in helping to prevent man-in-the-middle attacks. Online data transfers (between websites and individuals, for example) should never take place without a firm TLS handshake, as this confirms that the connection in question is both authenticated and secure.

While self-signed certificates do exist, they don't offer the same security benefits promised when instead issued by trusted certificate authorities.

Understanding SSL/TLS certificates

SSL/TLS certificates form the basis of modern web security, offering enhanced encryption and authentication to help prevent many types of attacks, including difficult-to-detect man-in-the-middle schemes. To put it simply: when users first connect to a website, a TLS handshake occurs, telling both parties that the other is safe to share and transfer data with. A site can only perform this secure connection if it has an SSL certificate installed on its server and issued by a trusted certificate authority. This ensures that any data sent and received is encrypted.

How SSL certificates prevent MITM attacks

Digital certificates bring a proactive approach to MITM prevention by establishing secure and authenticated connections and encrypting the data transmitted between a user's browser and a server. This encryption ensures that any intercepted data cannot be read or altered by attackers, maintaining the integrity and confidentiality of the communication.

Common MITM attack techniques

MITM attacks can take many forms. This versatility makes these attacks uniquely difficult to assess and prevent; even those who are aware of this concept may still struggle to identify different types of MITM attacks. Common concerns include:

ARP spoofing & DNS spoofing

Centered around Address Resolution Protocol (ARP) vulnerabilities, ARP spoofing (occasionally referred to as ARP poisoning) occurs when a device on the local area network gains access to data meant for a different device on that same network. All the malicious actor needs is the MAC address of the device it intends to gain control of—and then it's possible to pose as the device whenever desired. The host then unknowingly sends sensitive information to the compromised device, assuming that this is perfectly safe.

Similar to ARP poisoning, DNS spoofing aims to trick Domain Name System (DNS) servers into assuming that they have received authentic data—when, in reality, attackers are springing their traps. This typically relies on redirection to fake or malicious websites. Fake responses may be sent, for example, reflecting incorrect IP addresses.

Most web browsers will alert users to the possibility that they are attempting to access an unsecured site. HTTPS protocol and SSL certificates can ensure that the user's intended DNS server is the proper one—and not set up by malicious actors on a phishing expedition.

Session hijacking

Also known as cookie hijacking, session hijacking involves a sudden takeover of an internet session with the hopes of stealing data or making transactions without the users' consent. Every time a user connects to a website, a cookie is stored in the web browser, acting as a unique identifier to keep the user authenticated and track their browsing habits.

Threat actors can steal these cookies and use them to take over the web browsing session without being detected. The impact of this could be dire, as session hijacking can lead to bank accounts being wiped out, credit cards being charged, and personal data being stolen.

SSL encryption can act as a line of defense against session hijackers. If it's impossible to gain the session ID and cookie data because it's encrypted, the hacker must find a new method to complete the attack.

SSL stripping

Often referred to as HTTP downgrade attacks, SSL stripping involves the dangerous manipulation of HTTPS connections. An attacker intercepts the initial connection request from a client to a server and downgrades the secure HTTPS connection to an unsecured HTTP connection without the user's knowledge.

This allows the attacker to intercept data between the server and the client. SSL stripping results in the server sending an unencrypted HTTP version of the site to the man in the middle, who then has access to troves of sensitive information.

It’s essential for websites to keep their SSL certificates up to date to avoid any expired or invalid certificates that will leave their site vulnerable to this type of attack. Using an automated certificate lifecycle management tool, especially with the switch to 90-day SSL validity periods coming soon, takes the worry out of keeping your digital certificates current and valid.

A Web Application Firewall (WAF) can also go a long way in alerting web hosts to potential SSL stripping attacks. 

Additional security measures

Any effort to combat MITM attacks should encompass real-time website monitoring and regular alerts. Because these attacks are so tough to detect, it is absolutely imperative to respond as quickly as possible when malicious behavior is finally uncovered. A swift response can limit the scope of the damage.

Also essential: in-depth training. While even sophisticated individuals will sometimes fall prey to MITM, enterprises need to alert all employees (not just IT staff) to the potential for these attacks. Training should also reveal common signs of intercepted communication, along with strategies employees can take to keep online interactions secure.

Best practices for SSL certificates

While SSL/TLS certificates can provide strong protection, they must be properly deployed and continually managed, with proactive renewal processes limiting the potential for outages.

Many enterprises now rely on automated certificate lifecycle management (CLM) solutions to bring greater reliability and significant cost savings to this essential process. These systems bypass time-consuming manual tasks and help to avoid human errors.

Secure your website with Sectigo SSL/TLS certificates

As you take steps to improve your security posture, look to Sectigo for support. You will find a range of SSL/TLS certificate options, including certificates at all validation levels. We also offer a trusted CLM: Sectigo Certificate Manager (SCM), which streamlines critical certificate lifecycle processes and can dramatically reduce the likelihood of outages. Check out our digital certificate offerings or get started with a free trial of SCM.

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