A man-in-the-middle attack, or MITM attack, is a cyberattack in which an attacker secretly intercepts communication between two parties that believe they are communicating directly with each other.
By positioning themselves between a user and a website, application, or network service, the attacker may monitor traffic, steal sensitive information, impersonate one of the parties, or modify data before forwarding it to its intended destination.
Information exposed in a successful MITM attack can include login credentials, payment information, confidential business data, and authentication or session tokens.
Man-in-the-middle attacks are also sometimes called on-path attacks or adversary-in-the-middle (AiTM) attacks.
How Does a Man-in-the-Middle Attack Work?
A normal connection looks like this:
User → Website or Application
During a MITM attack, the communication path becomes:
User → Attacker → Website or Application
The attacker first needs to intercept or redirect the victim’s traffic. This may be done through techniques such as ARP spoofing, DNS manipulation, a malicious Wi-Fi access point, or a phishing proxy.
Once positioned in the communication path, the attacker can attempt to observe or manipulate the data being exchanged.
Unencrypted traffic is particularly vulnerable. Encrypted HTTPS connections provide significantly stronger protection because TLS encrypts data and verifies the identity of the server. However, attackers may still attempt certificate attacks, SSL stripping, or session-token theft.
Common Types of Man-in-the-Middle Attacks
There are several techniques attackers can use to conduct a MITM attack.
ARP Spoofing
ARP spoofing, or ARP poisoning, involves sending falsified network messages so that devices on a local network send traffic through the attacker’s device instead of directly to the legitimate gateway.
The attacker can then relay the traffic to its original destination while attempting to monitor or modify it.
DNS Spoofing
DNS spoofing or DNS poisoning manipulates the process that translates domain names into IP addresses.
A victim may enter the correct website address but be redirected to infrastructure controlled by an attacker. This can be used to steal credentials, distribute malware, or support other MITM techniques.
Evil Twin Wi-Fi
An evil twin attack uses a malicious Wi-Fi access point designed to look like a legitimate network.
For example, an attacker may create a network using the name of a hotel, airport, or café Wi-Fi service. If users connect to it, their traffic passes through attacker-controlled infrastructure.
SSL Stripping
SSL stripping attempts to downgrade a secure HTTPS connection to an unencrypted HTTP connection.
If successful, data sent by the victim may become visible to the attacker. HTTPS, HSTS, and proper certificate validation help reduce this risk.
Session Hijacking and AiTM Phishing
Modern adversary-in-the-middle phishing may place a malicious proxy between a user and a legitimate login service.
The attacker relays the real authentication page while capturing credentials and potentially the resulting session token. Because the login occurs against the legitimate service, some forms of traditional multi-factor authentication may also be bypassed.
How to Detect a Man in the Middle Attack
MITM attacks are designed to remain unnoticed, but possible warning signs include:
- Unexpected browser certificate warnings
- A website loading over HTTP instead of HTTPS
- Unfamiliar or duplicate Wi-Fi network names
- Unexpected website redirects
- Unusual DNS responses
- Changes to network, proxy, or certificate settings
Security teams may also monitor for abnormal ARP activity, unauthorized access points, suspicious DNS behavior, or unexpected TLS downgrade attempts.
How to Prevent Man-in-the-Middle Attacks
Organizations can reduce the risk of MITM attacks through layered security controls.
Use HTTPS and Strong TLS
Websites and applications should enforce HTTPS and use secure TLS configurations. Encryption helps prevent intercepted traffic from being read or modified.
Validate Digital Certificates
Browsers and applications should validate TLS certificates correctly. Users should avoid bypassing certificate warnings when accessing sensitive services.
Secure DNS
DNSSEC, secure DNS resolvers, DNS monitoring, and encrypted DNS protocols can help reduce the risk of DNS manipulation.
Be Careful with Public Wi-Fi
Users should avoid sending sensitive information over unfamiliar or unsecured Wi-Fi networks. A trusted VPN can add an extra layer of encryption when using untrusted networks.
Use Strong Authentication
Multi-factor authentication improves account security, but organizations protecting high-value accounts should also consider phishing-resistant authentication methods such as FIDO2 security keys or passkeys.
Does HTTPS Prevent Man-in-the-Middle Attacks?
HTTPS is one of the most important defenses against MITM attacks.
TLS provides encryption, data integrity, and server authentication, making traditional network interception much more difficult.
However, HTTPS does not eliminate every MITM scenario. Risks can remain if attackers steal authenticated session tokens, compromise an endpoint, manipulate trusted certificates, or use sophisticated AiTM phishing techniques.
For this reason, HTTPS should be combined with secure DNS, strong authentication, endpoint security, and network monitoring.
How CDNetworks Helps Protect Data in Transit
CDNetworks supports secure content delivery using HTTPS and modern TLS protocols, including TLS 1.2 and TLS 1.3.
Securing communication between users, edge servers, and origin infrastructure helps protect data as it moves across the internet and reduces exposure to interception and tampering.
Combined with DNS security, certificate management, access controls, and continuous monitoring, encrypted content delivery forms an important part of a layered defense against man-in-the-middle attacks.
