Man-in-the-Middle (MitM) Attack

A Man-in-the-Middle (MitM) attack is a cyber-attack where a malicious actor secretly intercepts and possibly alters the communication between two parties who believe they are directly communicating with each other. This type of attack allows the attacker to eavesdrop, steal data, or inject malicious content without the knowledge of the sender or receiver.

MitM attacks are especially dangerous because they can be nearly invisible to victims. They are commonly used to steal login credentials, credit card information, or sensitive communications in both personal and enterprise environments.

Variants

MitM attacks come in various forms, depending on how and where they occur:

Network-Level Attacks

• ARP Spoofing: Exploits the Address Resolution Protocol (ARP) by sending forged ARP messages to associate the attacker's MAC address with the IP address of a legitimate host. This causes network traffic to be sent through the attacker's device, enabling monitoring or manipulation. Learn more
• DNS Spoofing: Alters DNS responses to redirect victims to malicious websites instead of legitimate ones.
• Evil Twin: Also considered a network-level attack, Evil Twin access points impersonate legitimate Wi-Fi networks to trick users into connecting, thus exposing all their traffic. Learn more

Application-Level Attacks

• SSL Stripping: Downgrades HTTPS connections to HTTP, allowing the attacker to intercept and modify unencrypted traffic.
• Email Spoofing and Forwarding: Redirects or alters emails in transit, often used for phishing or business email compromise (BEC).

Impact

The consequences of a MitM attack can be severe. Victims may unknowingly share sensitive data such as passwords, financial details, and private messages. For organizations, the attack can result in data breaches, financial losses, reputational damage, and regulatory penalties. In critical infrastructure, such as healthcare or banking, these attacks can disrupt operations and pose risks to public safety.

Discoverability

Detecting a MitM attack can be difficult due to its stealthy nature. Unlike brute-force or denial-of-service attacks, MitM often involves normal-looking network traffic. However, anomalies such as unexpected SSL certificate warnings, slow network performance, duplicate IP addresses, or unauthorized certificate authorities may signal an attack. Intrusion Detection Systems (IDS), endpoint monitoring, and SSL/TLS inspection tools can help identify and block MitM attempts.

Protection

Preventing MitM attacks requires a layered security approach that includes user awareness, network security practices, and encryption enforcement.

• Use HTTPS Everywhere: Always ensure websites use HTTPS with valid certificates. Employ browser plugins like HTTPS Everywhere to enforce encrypted connections.
• Public Wi-Fi Caution: Avoid conducting sensitive transactions on public Wi-Fi. Use VPN services to encrypt all internet traffic when connected to untrusted networks.
• Detect Evil Twin Networks: Use Wi-Fi scanning tools and endpoint protection software that can detect rogue access points and alert users or block connections.
• Defend Against ARP Spoofing: Implement static ARP entries in critical systems, enable Dynamic ARP Inspection (DAI) on managed switches, and monitor traffic with intrusion detection systems.
• Enable DNS Security: Use DNSSEC to authenticate DNS responses and help prevent DNS spoofing.
• Use Two-Factor Authentication: Even if credentials are intercepted, 2FA provides an extra layer of protection against unauthorized access.
• Keep Systems Updated: Regularly patch and update operating systems, browsers, and security software to close known vulnerabilities.