What Is a Man in the Middle (MITM) Attack?

    A man in the middle attack is when someone intercepts your communication to steal your data. Learn how they work and how to protect against them.

    Man in the Middle (MITM) Attack Introduction

    For cybersecurity professionals all over the world, certain types of online attacks remain difficult to track, trace, and subsequently stop before they damage infrastructure or steal data. One example is a man in the middle attack (MITM), where an attacker intercepts communication between two parties and can access, alter, or even block the communication entirely.

    These types of attacks pose a particular challenge to professionals as they are often difficult to detect, and can be relatively easy to implement by an attacker. Additionally, these attacks can be active over long periods without detection, with an increasing amount of data and credentials being intercepted by the attacker.

    Here, we explore the different types of man-in-the-middle attacks and how they work. Read on to learn more and discover what a MITM is and how your organization can prevent potential breaches.


    Man in the Middle Attack


    How a Man-in-the-Middle Attack Works

    Fundamentally, as the name suggests, a man in the middle attack is when a cyberattacker intercepts communications by positioning themselves between the two parties. However, this can be achieved in different ways, with certain access points offering easy access but only limited exchanges (such as a public Wi-Fi connection) and others offering more challenging access but the potential for significantly more data (network level).

    In whichever way attackers gain access, the end goal is to monitor potentially lucrative exchanges that provide them with sensitive personal data, financial data, or login credentials. Once they have the information they need, they can either end the man-in-the-middle attack or keep it open for future monitoring.

    MITM attacks usually consist of two phases:

    • Interception – An attacker intercepts and alters the communication between two parties using sniffing, DNS spoofing, SSL stripping, session hijacking, phishing, or a rogue access point.
    • Decryption – Once the attacker has intercepted the communication, they can use various methods to decrypt it. This can include using tools such as network protocol analyzers, password-cracking tools, and decryption software. It's worth noting that if the communication is encrypted using a strong encryption method like AES or RSA, and the attacker does not have the encryption key, it would be very difficult for them to decrypt it.

    Types of MITM Attacks, Techniques, and Tools

    There are many different types of MITM attacks, using various techniques and tools to make it possible for the attacker to intercept and alter communications. They include:


    Sniffing is a type of MITM attack in which an attacker intercepts and alters data packets passing through a given network. While often used for legitimate purposes, such as monitoring network activity and troubleshooting network issues, it can also be used for malicious purposes, such as stealing sensitive information or spreading malware.

    Sniffing can be accomplished using various tools, such as packet sniffers, which are software or hardware programs that can capture, analyze, and decode network traffic. These tools can be used to capture data packets that are sent over a network and can extract useful information such as login credentials, financial data, and other sensitive information.

    Two types of sniffing exist, and both can be detrimental when used by cybercriminals:

    • Passive sniffing: the sniffer only listens to the network traffic and does not interact with it.
    • Active sniffing: the sniffer interacts with the network traffic by injecting packets, or altering existing packets, to gather more information.

    Session Hijacking

    Session hijacking is a MITM attack that allows an attacker to take over an active communication session between two parties. The attacker intercepts and alters the communication, allowing them to gain access to sensitive information or control over the communication.

    The attacker can use various techniques to hijack a session, such as stealing session cookies, exploiting weaknesses in communication protocols, or using phishing or social engineering techniques to obtain login credentials. Once the attacker has taken over the session, they can use it to steal sensitive information, spread malware, or perform other malicious activities. This type of attack is particularly dangerous because it can be difficult to detect, and it allows the attacker to operate under the guise of a legitimate user.

    DNS Spoofing

    DNS spoofing is a MITM attack in which an attacker intercepts and alters DNS (Domain Name System) requests and responses. DNS is a system that translates domain names (such as www.example.com) into IP addresses that computers can use to communicate with each other. In a MITM DNS spoofing attack, an attacker intercepts and alters DNS requests and responses, redirecting the victim's traffic to a malicious server controlled by the attacker.

    The attacker can use this to perform various malicious activities, such as:

    • Redirecting the victim's browser to a phishing website that looks legitimate to steal login credentials or financial information.
    • Injecting malware into the victim's device by redirecting the victim's traffic to a website that serves malware.
    • Intercepting and reading the victim's sensitive information, such as login credentials, by redirecting the victim's traffic to a malicious server that acts as a proxy.
    • DNS spoofing can be performed using various techniques such as ARP spoofing, IP spoofing, DHCP spoofing, and exploiting vulnerabilities in the DNS protocol.

    Rogue Access Point

    A MITM rogue access point is a type of cyberattack in which an attacker sets up a fake wireless access point, often with a similar name to a legitimate access point, to intercept and alter communication between clients and the valid access point.

    Once a client connects to the rogue access point, the attacker can intercept and read the client's communication and inject new information into the interaction. This can allow the attacker to steal sensitive information or spread malware.

    A rogue access point can be set up using various techniques, such as:

    • Creating a fake wireless access point with a similar name to a legitimate access point to trick clients into connecting to it.
    • Exploiting vulnerabilities in wireless networks to gain unauthorized access to a legitimate access point and then altering its settings to intercept client's communication.
    • Using a rogue device, such as a smartphone or a laptop, to create a fake wireless access point and lure clients to connect to it.

    It is important to note that Rogue Access Point attacks can be mitigated by using a strong wireless network security like WPA3, a VPN, and being aware of the wireless networks you connect to.

    Man in the Middle Attack Prevention

    Man-in-the-middle attack prevention takes several guises within the framework of common cybersecurity practices. However, it is important to remember that no single approach or tool acts as a comprehensive MITM attack prevention system, so combining these approaches is paramount when thinking about attack detection.

    • Encryption: Using encryption can help protect the communication between two parties from being intercepted and read by an attacker. This can include using HTTPS for web browsing, VPN for remote connections, and SSL or TLS for email.
    • Authentication: Using strong authentication methods, such as multi-factor authentication , can help prevent attackers from gaining access to sensitive information by stealing login credentials.
    • Firewall: A firewall can help prevent unauthorized access to a network and can also block suspicious traffic.
    • Network segmentation: Segmenting the network can help prevent an attacker from moving laterally within the network once they have gained access.
    • Use of anti-virus, anti-malware, intrusion detection, and prevention systems: These can help identify and block malicious traffic and help in identifying any malicious activities on the network.
    • Education and awareness: Keeping users informed about potential threats and providing them with the knowledge to identify and prevent them can also be an effective way to prevent MITM attacks.
    • Keep software and systems updated: Regularly updating software and systems with the latest security patches can help prevent attackers from exploiting known vulnerabilities.

    Protection from Man in the Middle Attacks with Mimecast

    While many of the above tools and techniques can help with man-in-the-middle attack detection and prevention, Mimecast provides additional web security to boost protection across the board. Featuring Targeted Threat Protection that helps to identify and block advanced MITM threats, comprehensive spam and virus protection that mitigates the opportunity for attackers to exploit devices and networks, and content control and data leak prevention tools to ensure inadvertent or malicious breaches are reduced.

    Additionally, dedicated secure messaging solutions that allows users to share confidential and sensitive information safely and securely, alongside large file send technology, provides an added layer of security that reduces the potential for MITM attacks.

    Conclusion: Man in the Middle Attacks

    For a huge range of businesses, MITM attacks can have a serious impact on data security and operational efficiency. Ensuring your organization is not only prepared but also vigilant to this type of threat is crucial to streamlined operations on a day-to-day basis.

    For more information on how Mimecast can help your cybersecurity team detect and prevent man-in-the-middle attacks, as well as other cybersecurity issues, contact us today or explore our blog.

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