What Is a MITM Attack? Types, Causes & Real Examples | DNSFilter

What Are Man-in-the-Middle (MITM) Attacks?

A man-in-the-middle (MITM) attack is a cyberattack where an adversary secretly intercepts and possibly alters communication between two parties who believe they are interacting directly. The attacker may use this position to eavesdrop on sensitive information, manipulate messages, or redirect users to malicious destinations—often without either party detecting the intrusion.

Overview of Man-in-the-Middle Attacks

MITM attacks rely on stealth and deception. An attacker positions themselves between a user and a trusted system—such as a website, API, or email server—and intercepts data flowing between the two. This may happen through network manipulation, credential theft, or exploitation of misconfigured encryption protocols.

Attackers often exploit unsecured public Wi-Fi networks, outdated encryption standards, or vulnerable devices to gain access. Once in place, they can extract credentials, modify requests, or redirect traffic to attacker-controlled infrastructure.

Types of Man-in-the-Middle Attacks

MITM attacks can be executed using a range of technical methods designed to intercept or alter data in transit. Common types include:

Address Resolution Protocol (ARP) Spoofing

The attacker sends falsified ARP messages to a local network, associating their device with the IP address of another system. Traffic meant for the legitimate destination is redirected to the attacker.

Domain Name System (DNS) Spoofing

By manipulating DNS responses, attackers redirect users to fraudulent websites that mimic legitimate services, allowing credential theft or malware injection.

Secure Sockets Layer (SSL) Stripping

This technique downgrades HTTPS connections to unencrypted HTTP, exposing sensitive data like login credentials or payment information during transmission.

Session Hijacking

Attackers capture session tokens or cookies to impersonate users and access web applications without reauthentication.

Rogue Wi-Fi Access Points

Also known as “Wi-Fi eavesdropping” or “Wi-Fi sniffing,” malicious or spoofed Wi-Fi hotspots mimic trusted networks. Once users connect, attackers can intercept or manipulate all unencrypted traffic. And if the Wi-Fi settings are set up to remember networks, victims will reconnect in the future automatically when they’re nearby.

Email Interception

Attackers insert themselves into email conversations by compromising mail servers or accounts. In live exchanges, they may alter messages or impersonate users mid-thread.

Causes of Man-in-the-Middle Attacks

Several factors increase the likelihood of successful MITM attacks:

• Use of unsecured or poorly encrypted public Wi-Fi networks
  
  
• Websites lacking HTTPS or improperly configured SSL certificates
  
  
• Unpatched operating systems or vulnerable network devices
  
  
• Social engineering tactics, such as phishing, that lead to credential reuse or session exposure

Effects of Man-in-the-Middle Attacks

MITM attacks can lead to serious outcomes for both users and organizations:

• Credential theft – Including usernames, passwords, and session cookies
  
  
• Financial loss – Resulting from intercepted transactions or fraudulent activity
  
  
• Data leakage – Exposure of sensitive communications, including intellectual property, or personal data
  
  
• Reputational damage – Especially in regulated industries or customer-facing breaches
  
  
• Operational disruption – Through tampering with internal communications or redirecting users to malicious sites

In targeted scenarios, MITM techniques may also be used for espionage or long-term surveillance. These attacks are often difficult to detect and may persist for long periods if monitoring tools fail to observe anomalies in traffic flow.

MITM vs. Other Attacks

MITM attacks operate during active sessions, whereas phishing and replay attacks often occur before or after a communication session has started or ended.

Examples of Man-in-the-Middle Attacks

Real-World Examples

• Superfish (2015) – Superfish was adware that was pre-installed on commercial Lenovo laptops that performed SSL interception, allowing traffic manipulation through MITM techniques.
  
  
• OpenSSH (2025) – Vulnerabilities in the suite of secure networking utilities that leverage Secure Shell (SSH) were discovered in early 2025. One was active for over a decade before discovery.
  
  
• Firesheep (2010) – A Firefox extension demonstrated session hijacking on public Wi-Fi, allowing attackers to take over Facebook and Twitter sessions via unsecured cookies.

Who Might Need Protection from MITM Attacks?

• Remote and mobile employees – Often rely on public or shared networks without full endpoint protection.
  
  
• Organizations with BYOD policies – Personal devices can expose corporate infrastructure to MITM risks.
  
  
• Legal, healthcare, and financial institutions – Handle sensitive communications requiring tamper-proof transmission.
  
  
• Executives and finance staff – Prime targets for credential theft, wire fraud, or email interception.

Related Terms

• Malware – MITM attacks may be used to deliver or facilitate malware infections by intercepting downloads or injecting malicious payloads into otherwise legitimate traffic.
  
  
• Phishing – While phishing typically deceives users into disclosing credentials, MITM attacks may exploit those stolen credentials or operate in tandem with phishing campaigns to hijack sessions or alter communications.
  
  
• Domain Generation Algorithm (DGA) – Attackers who gain access through MITM may use DGAs to maintain covert communication with command-and-control infrastructure, particularly in cases involving malware distribution.
  
  
• Zero-Day – MITM attacks may exploit zero-day vulnerabilities in browsers, network protocols, or software to silently insert themselves into a communication stream without detection.

Stop MITM Attacks Before They Take Hold

MITM attacks exploit unsecured networks, weak encryption, and misrouted traffic. DNSFilter helps detect and block MITM techniques by identifying and blocking suspicious DNS activity.

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