What is a Man-in-the-Middle (MITM) Attack?
Man-in-the-middle attacks, or MITM attacks, are a kind of cybersecurity attack where hackers secretly listen to the communication between two devices. They do this by inserting themselves between the two devices that are talking to each other. This lets the hackers listen in on the conversation without the devices knowing, which is why it's called a "man-in-the-middle" attack.
MITM attack example
Here's an analogy: Imagine Alice and Bob are talking to each other, and Eve wants to secretly listen in on their conversation without them knowing. Eve could trick Alice into thinking she's Bob and trick Bob into thinking she's Alice. This way, Alice would unknowingly share her part of the conversation with Eve, who could then gather information, change the response if needed, and pass it on to Bob (who thinks he's talking to Alice). This way, Eve can hijack their conversation without them realizing it.
Types of Man-in-the-Middle Attacks
Rogue Access Point
When devices with wireless cards search for a network, they often connect to the one with the strongest signal. Attackers can exploit this by creating their own fake wireless access point. Devices nearby might connect to this fake network, allowing the attacker to control and manipulate the victim's network traffic. The attacker doesn't need to be on a trusted network; they just need to be physically close enough to the victim.
ARP Spoofing
ARP (Address Resolution Protocol) resolves IP addresses to physical MAC addresses in a local network. An attacker can trick devices into sending data to the wrong MAC address by responding to ARP requests with their own MAC address. This lets the attacker intercept private traffic between two hosts and potentially gain access to sensitive information like session tokens, which could lead to unauthorized access to accounts.
mDNS Spoofing
Multicast DNS (mDNS) is used for local network name resolution, making it easy for users to connect devices without knowing their exact addresses. Attackers can exploit this by responding to mDNS requests with fake data, tricking devices into trusting the attacker's device as a trusted network device for a period of time.
DNS Spoofing
DNS (Domain Name System) resolves domain names to IP addresses. Attackers can use DNS spoofing to introduce false DNS cache information to a host, leading the victim to send sensitive information to a malicious host, thinking it's a trusted source. This can be done by resolving the address of a DNS server to the attacker's address, making it easier for the attacker to redirect traffic to malicious servers.
Man-in-the-Middle Attack Techniques
Sniffing
Attackers use tools to capture and analyze network packets. By using specific wireless devices in monitoring or promiscuous mode, they can see packets not meant for them, like those intended for other hosts.
Packet Injection
Attackers can use monitoring mode to insert malicious packets into data streams. These packets can appear as part of the normal communication but are harmful. This technique often involves sniffing first to understand how to craft and send the packets.
Session Hijacking
Many web applications use a login system that generates a temporary session token. Attackers can sniff traffic to find this token and use it to make requests as the user without needing to spoof their identity.
SSL Stripping
HTTPS is a common way to secure communications, but attackers can use SSL stripping to intercept packets and change HTTPS requests to HTTP, making the communication unencrypted. This allows attackers to see sensitive information in plain text.
How to Detect and prevent a Man-in-the-Middle Attack
Detecting a Man-in-the-middle attack can be hard if you're not actively looking for it. If you don't check for signs of interception, the attack might go unnoticed until it's too late. Checking for page authentication and using tamper detection are key methods, but they might need extra investigation afterward.
To prevent MITM attacks, it's important to take precautions before they happen. Being careful with your browsing habits and avoiding risky areas can help keep your network secure. Here are five best practices to prevent MITM attacks from compromising your communications:
Having strong encryption on wireless access points is important to prevent unauthorized access. Weak encryption can lead to brute-force attacks and man-in-the-middle attacks. It's crucial to change default router login credentials to protect against attackers who could change DNS servers or infect the router with malware.
Using a Virtual Private Network (VPN) can create a secure environment for sensitive information within a network. VPNs use encryption to secure communication, even on shared networks.
Force the use of HTTPS to securely communicate over HTTP, preventing attackers from using sniffed data. Websites should only use HTTPS, and users can install browser plugins to enforce HTTPS.
Public key pair-based authentication, like RSA, can be used to ensure that you are communicating with the intended recipient and not an attacker trying to intercept your communication.