Man-in-the-Middle Attacks and Protection

Man-in-the-Middle Attack: How It Works and How to Stay Safe

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

A Man-in-the-Middle (MITM) attack is a cybersecurity attack where a hacker secretly positions themselves between two communicating parties - usually a user and a website, app, or service. The attacker listens, intercepts, or even modifies the communication without the victim noticing.

The attacker’s main objective is usually to steal sensitive information like:

• Login credentials
• Bank account details
• Credit card numbers
• Session cookies and authentication tokens
• Private messages and API requests

MITM attacks target users of financial apps, SaaS platforms, e-commerce websites, online banking, corporate networks, and any service that requires logging in.

These attacks can lead to:

• Identity theft
• Unauthorized fund transfers
• Account takeovers
• Password changes
• Full access to user accounts

And the most dangerous part?
The victim typically has no idea the attack is happening.

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How Does a MITM Attack Work? ​

Let’s break it down with a simple real-life scenario:

You receive an email that looks like it’s from your bank.
It asks you to “confirm your account details,” urging you to click a link.

You click it.
It takes you to a fake website that looks identical to your bank’s login page.

You enter your username and password…
…and boom.
You just handed your credentials directly to the attacker.

This type of MITM attack combines:
Phishing
Fake login pages
Traffic interception
Session hijacking
In the background, the attacker is silently capturing every detail you enter.

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The Two Main Stages of a MITM Attack ​

MITM attacks usually happen in two major phases:

Interception​

The attacker "gets in the middle" of the victim’s communication.

Decryption​

The attacker decrypts or manipulates the data without raising suspicion.

Let’s go deeper into both stages

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Interception Phase - Capturing the Connection ​

This is where the attacker gains access to your communication channel before it reaches its real destination.

Here are the most common interception techniques

1. Fake WiFi Hotspots (Evil Twin Attack) ​

Attackers create public WiFi networks with legit-looking names like:

Starbucks_Free_WiFi
Airport_Guest
Library_Public_WiFi

Once you connect, they can see everything you send or receive.

2. IP Spoofing​

The attacker forces your device to communicate with their server instead of the real one by modifying packet headers.

3. ARP Spoofing​

The attacker links their MAC address to a legitimate IP on the network, redirecting traffic through their machine.

Python Example: ARP Spoofing (for education only)​

from scapy.all import *

def arp_spoof(target_ip, gateway_ip):
    packet = ARP(op=2, pdst=target_ip, psrc=gateway_ip)
    send(packet, loop=True, verbose=False)

arp_spoof("192.168.1.25", "192.168.1.1")

4. DNS Spoofing / DNS Poisoning​

The attacker corrupts DNS records so users are redirected to fake websites designed for credential theft.

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Decryption Phase - Reading Encrypted Traffic ​

Once communication is intercepted, the attacker must bypass encryption.

Here are the most common decryption techniques:

HTTPS Spoofing​

The attacker sends a fake certificate that appears valid, tricking the victim into continuing.

SSL BEAST Attack​

Targets weaknesses in TLS 1.0 to decrypt secure cookies and sessions.

SSL Hijacking​

The attacker sends forged keys to both the server and the user, controlling the entire connection.

SSL Stripping​

Downgrading an HTTPS connection to HTTP to remove encryption completely.

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Example: Simple HTTP Traffic Capture in Python​

from http.server import BaseHTTPRequestHandler, HTTPServer

class CaptureHandler(BaseHTTPRequestHandler):
    def do_POST(self):
        length = int(self.headers.get("Content-Length"))
        data = self.rfile.read(length)
        print("[Captured]:", data.decode())
        self.send_response(200)

server = HTTPServer(("0.0.0.0", 8080), CaptureHandler)
server.serve_forever()

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Types of MITM Attacks ​

MITM attacks come in many forms, including:

• WiFi-based attacks
• ARP spoofing
• DNS spoofing
• Session hijacking
• Email hijacking
• SSL stripping
• Rogue access points
• Malware-based traffic interception

Each type has its own techniques, but the goal is always the same:
intercept the communication and steal sensitive data.

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How to Protect Yourself From MITM Attacks ​

Here are practical, effective steps to stay safe:

Always check for HTTPS​

Look for the lock icon before entering sensitive info.

Don’t click suspicious email links​

Instead of clicking, type the website address manually.

Use a VPN on public WiFi​

VPN encrypts your traffic - even if you're connected to a hacked network.

Avoid unsecured WiFi networks​

If it has no password, it’s dangerous.

Enable Two-Factor Authentication (2FA)​

Even if your password is stolen, the attacker can’t log in.

Update your OS and browser regularly​

Updates patch encryption vulnerabilities.

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MITM Protection for Developers ​

If you're building websites or apps, strong security practices are essential:

Use modern protocols like TLS 1.3​

Enable HSTS to force HTTPS​

Prevent mixed content​

Implement certificate pinning​

Secure your cookies​

Example: Secure Cookies in PHP​

setcookie("session_id", $token, [
    "secure" => true,
    "httponly" => true,
    "samesite" => "Strict"
]);

Example: Secure Sessions in Node.js​

app.use(session({
    secret: "super_secret_key",
    cookie: {
        httpOnly: true,
        secure: true,
        sameSite: "strict"
    }
}));

These configurations prevent attackers from hijacking sessions or injecting malicious scripts.

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Final Thoughts ​

A Man-in-the-Middle attack is one of the most dangerous cyberattacks because victims rarely notice anything is wrong.
Attackers can silently intercept, read, and manipulate communication - especially on unsecured networks.

Staying safe requires:
Awareness
Secure browsing habits
VPN usage
HTTPS verification
And strong app-level security for developers
Cybersecurity isn’t optional anymore - it’s a daily necessity.