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What Is Man-in-the-Middle Attack and How to Prevent It

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The Man-in-the-Middle attack is a prominent cyberattack that has become infamous in recent years. However, it has been around since the 1980s, and it is one of the oldest types of cyber threats.  

In a nutshell, this attack constitutes an interception of a data transfer or other digital communication. By doing this, the attacker gains access to exchanges that are supposed to be secured. 

The MitM attack usually entails eavesdropping and can also include distributing malicious data to the existing parties in a conversation — with the attacker staying under the cover of a legitimate participant. It can also include impersonation as one of the legitimate parties to obtain other sensitive data. The end goals of MitM threats can be different — to steal someone’s identity, make fund transfers, change a user’s login credentials, gain access to financial institutions’ or eCommerce platforms’ data, and many more. 

In the guide below, you can learn the nitty-gritty details about MitM attacks — and how to tackle them for your cyber protection. 



What Is Man-in-the-Middle Attack?

A Man-in-the-Middle attack can be executed on a data transfer between a web server and a client and on a private communication exchange between individual users over a messaging platform. It can also target credentials during authentications with payment platforms and many more cases.  

MitM Attack Definition

In essence, a MiTM attack consists of an attacker gaining unauthorized access to data transfers that should be secure and private. They succeed by inserting themselves as a relay or a proxy in a standard exchange — getting ‘in the middle’ between two other parties. 

Man-in-the-Middle attacks can be considered a type of session hijacking. They often are not caught, even though they can cause severe data loss and damage. 

MITM Attack visualised - Crashtest Security

How Are Man-in-the-Middle Attacks Performed?

Different online security loopholes may allow a MitM attack to be executed. 

The steps usually follow a particular path, or attack progression, with the attacker intercepting traffic at first and then decrypting it in an unnoticed way to get to the valuable data. 

The interception can occur in several ways. The easiest one is setting up an open network where users can easily log in — and then steal their data exchanges. 

More elaborate interception methods include IP, ARP, or DNS spoofing. In the case of IP spoofing, the malicious user pretends to be an application by changing the packet headers in an IP address. ARP spoofing involves using fake ARP messages to link the attackers’ MAC address to the victim’s IP. As for DNS spoofing, also known as DNS cache poisoning, the attacker gains access to a DNS server and changes the address record of a website. 

Once the attacker has inserted themselves in the middle of data exchange, they have to find a covert way to decrypt the information contained in the Secure Sockets Layer (SSL) traffic. This can be done through methods like HTTPS spoofing, SSL BEAST, SSL hijacking, and SSL stripping, among others. 

Types of Man-in-the-Middle Attacks

As Man-in-the-Middle attacks can cause different vulnerabilities, there are a couple of main types of such attacks. 

Here are the most popular MitM attacks:

  • Wi-Fi eavesdropping
  • SSL hijacking
  • SSL stripping
  • Email hijacking
  • Browser cookies theft
  • Rogue access point (Wi-Fi pineapple) 
  • Internet Control Message Protocol (ICMP) redirection
  • Dynamic Host Configuration Protocol (DHCP) spoofing
  • HTTPS spoofing
  • IP spoofing
  • DNS spoofing 

The last three in the list correspond to the methods of interception described in the previous section. 

MitM attacks can also be categorized as either made during an active or a passive session. This relates to the exact activities of the attacker — whether they are simply eavesdropping on a communication channel or actively tampering with the ongoing exchange. 

What Types of Attacks Are Similar to a MITM Vulnerability?

As already mentioned, Man-in-the-Middle attacks are a type of session hijacking. Other kinds of this threat include sniffing, sidejacking, and Evil Twin. 

Sniffing entails the interception of data a device sends and receives. Sidejacking, on the other hand, includes gaining unauthorized access to session cookies which may contain login data that can be used for hijacking user sessions. 

Last but not least, Evil Twin is a type of attack based on session hijacking in which legitimate Wi-Fi networks are duplicated so that the attacker gains access to users who think they’re logging in to the network traffic. 

Real-Life Examples for Man-in-the-Middle Attacks

The world cyber threat records have numerous examples of Man-in-the-Middle attacks that have affected different types of businesses, large international organizations, and even national authorities. 

For example, the Organization for the Prohibition of Chemical Weapons (OPCW) was targeted by a Man-in-the-Middle attack from Russian spies in 2018. Back in 2011, the Dutch certificate authority DigiNotar suffered a breach in which fake certificates were issued, which were then used for MitM attacks. 

How to Prevent MitM Vulnerabilities

For end-users, there are practical ways to stay away from MitM attacks. They include:

  • Not logging from your mobile devices to Wi-Fi networks that are not password-protected 
  • Logging out of applications when you’re not using them
  • Avoiding public Wi-Fi connection networks 
  • Reading browser notifications about the security of visited websites

As for applications and websites, it’s essential to use the latest updates for secure connection protocols like TLS and HTTPS and stick to strong encryption and verification methods. 

How to Detect and Remove a Man-in-the-Middle Attack

Catching MitM threats can be tough to track, as they are often very discrete attacks. That’s probably the most characteristic thing about the common types of threats that such interception entails. Your best bet is to use dedicated software to monitor and identify if anyone is trying to or already has gained access to your data exchanges. 

Do you know if your systems are protected against man-in-the-middle attacks? Crashtest Security’s powerful Vulnerability Testing Software can help you verify any vulnerabilities that you can fix and prevent all kinds of cyber threats. 

Video: MITM Attack Explained

Man-in-the-middle attack explained in a video
How to prevent a man-in-the-middle attack, explained in a video

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