One of the most deceptive security threats in cybersecurity is a man-in-the-middle (MITM) attack. Attackers secretly intercept communications, making it seem like data is flowing between trusted parties while they manipulate the information. These attacks can steal login credentials, alter transactions, and expose private conversations.

We'll go over:

• How a man-in-the-middle attack works
• The different types of MITM attacks
• Methods to detect and prevent MITM attacks

What is a man-in-the-middle attack?

A man-in-the-middle (MITM) attack is when a hacker sneaks into a conversation between two parties and intercepts their data—without them knowing. Think of it like someone tapping into a phone call, except instead of just listening, they can also change what’s being said. The attacker sits between the sender and receiver, capturing messages, altering details, or even injecting fake information, all while keeping both sides in the dark.

What is the main goal of a MITM attack?

The main goal of a MITM attack is to gain unauthorized access to sensitive data. Attackers may steal login credentials, capture financial details, or manipulate transactions. Some use MITM techniques to spread malware, alter communications, or conduct espionage. The attack is designed to remain undetected while providing the attacker full control over the intercepted data.

How a man-in-the-middle attack works

Instead of data moving directly between two parties, an attacker sneaks in, intercepting messages along the way.

Sometimes, they just listen. Other times, they manipulate what’s being sent—switching out banking details, injecting malware, or downgrading security protections to make future attacks even easier. The trick is staying invisible, so neither side suspects a thing.

Stages of a MITM attack

An MITM works in stages. Below is the process that helps attackers stay hidden while intercepting communications.

Getting into position

First, the attacker needs a way in. This can happen through spoofing, where they trick devices into sending data their way, or Wi-Fi eavesdropping, where they create a fake public network that looks legitimate. If the target connects, the attacker sees everything they do online.

DNS hijacking is another method, where the attacker reroutes traffic to fake websites that look just like the real ones but are designed to steal passwords.

Interception and decryption

Once the attacker has access, they start capturing traffic. If the data isn’t encrypted, it’s easy to read. If it is, they might try HTTPS stripping — a technique that forces a secure site to load as an unprotected version. Weak encryption makes their job even easier, letting them decode messages and extract sensitive details.

Altering and forwarding data

Not all MITM attacks stop at spying. Some involve tampering with the data before sending it along. Something like changing account numbers in a wire transfer request or injecting malware into a software download.

Since everything appears normal to the victim, they have no idea their information has been manipulated. That’s why MITM attacks can be so dangerous—they often go unnoticed until serious damage is done.

Types of man-in-the-middle attacks

MITM attacks come in different forms, but they all follow the same playbook:

• Get between two parties
• Intercept their data
• Either steal or manipulate it

Here’s how they do it.

Packet sniffing

Attackers use packet sniffing tools to capture network traffic as it moves between devices. If the data isn’t encrypted, they can see everything—login credentials, credit card numbers, even private messages. IT teams use packet sniffers for troubleshooting, but in the wrong hands, they’re a goldmine for cybercriminals.

ARP spoofing

ARP spoofing tricks devices into thinking the attacker’s computer is the network gateway, redirecting traffic their way. Once that happens, the attacker can monitor or modify data before it reaches its real destination. This attack only works on local networks, but it’s a common trick in office environments and public Wi-Fi setups.

DNS spoofing

DNS spoofing sends users to fake websites that look real but are built to steal credentials. The attacker corrupts the DNS cache, replacing the real IP address of a website with their own. Victims might enter login details or payment info, never realizing they’re handing it straight to an attacker.

HTTPS stripping

HTTPS stripping downgrades a secure connection to an unencrypted one, making it easier to steal sensitive data. When you visit a site, your browser requests a secure HTTPS connection, but an attacker can interfere with that request, forcing the page to load over HTTP instead. Since many users don’t check for the missing padlock in the address bar, attackers can scoop up login credentials without any resistance.

Email hijacking

Email hijacking lets attackers intercept or manipulate emails between two parties. This is especially common in financial fraud, where attackers alter invoices to trick victims into sending money to the wrong account. Once funds are transferred, they’re gone.

Wi-Fi eavesdropping

Attackers set up fake Wi-Fi networks with names like “Free Airport Wi-Fi” to lure in victims. Once connected, everything the victim does online—banking, messaging, logging into accounts—is visible to the attacker. Even legitimate public networks can be risky if encryption is weak.

SSL hijacking

SSL hijacking allows attackers to intercept encrypted traffic by manipulating SSL/TLS certificates. If they pull it off, they can read, modify, or inject data into a secure connection, giving them access to passwords, banking details, or private conversations.

Common examples of MITM attacks in the real world

MITM attacks can lead to financial losses, data breaches, and compromised personal information. Here, we'll take a look at some real-world examples.

Financial fraud

In 2011, Dutch certificate authority DigiNotar suffered a severe security breach. Hackers infiltrated their systems and issued fraudulent digital certificates, including one for Google domains. This fake certificate was used in Iran to intercept and monitor communications, leading to a massive compromise of user data. The breach's fallout was so extensive that DigiNotar declared bankruptcy shortly thereafter.

Corporate espionage

Between 2010 and 2013, the UK's Government Communications Headquarters (GCHQ) conducted a covert operation, dubbed "Operation Socialist", targeting Belgium's largest telecom provider, Belgacom.

GCHQ infiltrated Belgacom's systems using a technique called "Quantum Insert," redirecting employees to malicious websites to install malware. This breach allowed GCHQ to access sensitive data and monitor communications without detection.

Session hijacking

In 2010, a Firefox extension called Firesheep showcased how vulnerable unsecured Wi-Fi networks could be. This tool allowed attackers to hijack active web sessions by capturing unencrypted cookies, granting them unauthorized access to users' accounts on sites like Facebook and Twitter. The incident highlighted the need for websites to adopt HTTPS to protect user sessions.

Man-in-the-browser attacks

The Zeus Trojan is a notorious example of a man-in-the-browser attack. This malware infects a user's browser, intercepts login credentials for online banking, and can even modify transaction details without the user's knowledge. Zeus has been responsible for significant financial theft worldwide.

Public Wi-Fi attacks

During the COVID-19 pandemic, more people worked from home and used video calls on platforms like Zoom. Many didn’t check their security settings, which led to a wave of “Zoom-bombing.” Attackers sneaked into meetings, listened in, or caused chaos. These incidents showed why securing online meetings and avoiding unprotected networks is so important.

How attackers bypass security measures

Most MITM attacks fail when encryption is strong and network security is tight. But hackers are always finding new ways to get around defenses. One method is certificate poisoning, where attackers inject fake SSL certificates that trick devices into trusting malicious connections. Another is session hijacking, which we've already covered.

Some hackers don’t break encryption—they avoid it altogether. Social engineering attacks trick users into clicking fake security warnings or downloading malicious VPNs that route traffic through an attacker’s server. Others use malware to hijack encryption keys, giving them full access to encrypted messages. Even when security tools are in place, human error and overlooked vulnerabilities still leave plenty of openings for attackers to exploit.

Signs of a potential MITM attack

Most MITM attacks happen in the background, but sometimes there are warning signs. Strange login activity, odd website behavior, or security alerts could mean someone is messing with your connection. If you notice any of these, it’s worth taking a closer look.

Security warnings that don’t make sense

If your browser suddenly warns you that a site’s SSL certificate is invalid, that’s a red flag. Secure sites should always have valid HTTPS encryption. If a trusted site loads with a warning—or worse, without HTTPS at all—an attacker might be intercepting your connection.

Websites that don’t look right

Ever visit a site you know well, but something feels off? Maybe the images aren’t loading, the layout is broken, or the login page looks slightly different. Attackers running DNS spoofing or HTTPS stripping can redirect you to fake versions of real sites to steal your credentials.

Login activity that doesn’t match your location

Getting alerts about logins from places you’ve never been? That could mean an attacker intercepted your session or stole your credentials in transit. If you didn’t suddenly move across the country, someone else might be using your account.

A connection that feels slower than usual

Some MITM attacks reroute your traffic through an attacker’s system, which can cause delays or inconsistent performance. Of course, slow internet isn’t always a sign of hacking—it could just be your ISP having a bad day—but if your connection drags only on secure sites, something’s up.

Redirects to pages you didn’t expect

Clicked on your bank’s login page but ended up somewhere else? That’s a problem. Attackers can redirect traffic to fake sites that look nearly identical to the real thing. Double-check URLs before entering any passwords.

If something seems off, don’t ignore it. Cybercriminals rely on people brushing off small red flags, so spotting them early can help you avoid bigger problems.

What should I do if I suspect a MITM attack?

If you think someone is intercepting your connection, act fast to limit the damage. Here’s what to do.

1. Disconnect from the network immediately

If you're on public Wi-Fi, switch to mobile data or a trusted network. This cuts off the attacker's access and prevents further exposure.

2. Stop entering passwords or sensitive data

If you notice odd redirects, security warnings, or strange website behavior, don’t enter any credentials or financial details until you confirm the connection is secure.

3. Use a different network and enable a VPN

If you must access accounts, use a trusted VPN to encrypt traffic and reduce exposure. Avoid public Wi-Fi for sensitive transactions, especially if you suspect an attack.

4. Change passwords for any accounts that may have been compromised

If an attacker intercepts your login details, changing your password quickly can lock them out before they do damage. Enable multi-factor authentication (MFA) if you haven’t already.

5. Scan your device for malware

Some MITM attacks involve malicious browser extensions or trojans that manipulate web pages. Run a full antivirus and malware scan to check for infections.

6. Check for unauthorized activity

Look for suspicious logins, unapproved transactions, or changes to account settings. If anything looks off, contact the service provider immediately.

7. Reset network settings (if needed)

If you're dealing with DNS spoofing or ARP poisoning, rebooting your router or flushing DNS settings can remove attacker-controlled configurations.

8. Report the attack

If this happened on a work device, notify your IT team. If financial data was stolen, contact your bank. Some attacks, especially large-scale ones, should be reported to local cybersecurity authorities.

Methods of detecting a man in the middle attack

MITM attacks are sneaky by design, but they aren’t invisible. Security tools can pick up on unusual network activity, certificate issues, or unexpected traffic changes. If something looks off, these methods can help expose an attack before it does serious damage.

Spot strange network activity

Security software scans traffic for anything unusual—like sudden changes in routing or unexpected device activity. Intrusion Detection Systems (IDS) and Intrusion Prevention Systems (IPS) flag suspicious patterns, helping to catch an attacker in action.

Catch fake security certificates

MITM attacks often involve tampering with encryption. TLS fingerprinting checks for strange SSL/TLS behavior, like expired certificates, odd encryption settings, or HTTPS connections that don’t seem as secure as they should be.

Inspect data packets

Deep Packet Inspection (DPI) breaks down network traffic to look for anything that shouldn’t be there—like modified requests, unencrypted data that should be encrypted, or strange redirects. If an attacker is messing with your connection, packet analysis can often prove it.

Check for weird DNS activity

If you type in a familiar website but end up somewhere else, DNS spoofing might be the problem. Security tools track DNS logs for signs of tampering, like unusual domain resolutions or sudden IP address changes.

Monitor for ARP tricks

Many MITM attacks rely on ARP spoofing to hijack traffic. Security tools can scan the network for duplicate MAC addresses or sudden shifts in device connections, which could mean someone is impersonating a trusted system.

Noticing small performance issues

Some MITM attacks reroute traffic, which can cause slight delays or lag when loading secure sites. A little slowdown isn’t always a big deal, but if encrypted sites suddenly take longer to load than usual, it might be worth investigating.

9 methods of preventing a man-in-the-middle attack

MITM attacks work best when security is weak or encryption is missing. A well-structured enterprise network design strengthens security by minimizing weak points attackers can exploit. The good news is that a few simple steps make it much harder for attackers to intercept or manipulate your data. Here’s how to keep your connections safe.

1. Use strong encryption

Encryption scrambles your data so only the intended recipient can read it. TLS 1.3 secures websites, end-to-end encryption (E2EE) protects messages, and a VPN shields your online activity. Without encryption, your data is an open book for attackers.

2. Turn on multi-factor authentication (MFA)

Even if an attacker steals your password, MFA makes them work harder to break into your account. A second verification step—like a code from an app or a fingerprint scan—can block unauthorized logins.

3. Double-check website security

A missing HTTPS in the address bar is a red flag. Clicking on the padlock icon lets you check a site’s security certificate. If the warning says the certificate is invalid, think twice before entering passwords or payment info.

4. Avoid public Wi-Fi for anything sensitive

Hackers love unsecured Wi-Fi. Some even create fake hotspots with names like “Free Public Wi-Fi” to trick people into connecting. If you must use public Wi-Fi, turn on a VPN to keep your traffic encrypted.

5. Secure your DNS settings

Some MITM attacks involve redirecting your traffic to fake websites. Using a secure DNS service with DNSSEC (DNS Security Extensions) helps prevent attackers from tampering with website addresses.

6. Keep devices and software updated

Attackers exploit outdated software to insert themselves into your connection. Updates patch security flaws that could be used for MITM attacks, so don’t ignore them.

7. Use security tools to monitor your network

Intrusion detection systems (IDS) and intrusion prevention systems (IPS) help spot unusual network behavior before an attacker can do damage. AI-powered security platforms can also flag suspicious activity in real time.

8. Force HTTPS connections

Some MITM attacks downgrade secure connections to unencrypted HTTP to make data easier to steal. Enabling “Always Use Secure Connections” in your browser forces HTTPS whenever possible.

9. Segment your network

Dividing your network into separate zones limits how far an attacker can move if they get in. An MITM attack in one section won’t automatically compromise everything else.

Legal and ethical implications of MITM attacks

A man-in-the-middle attack isn’t just bad news for security—it’s flat-out illegal in most places. Snooping on private communications without permission can lead to serious legal trouble under laws like the U.S. Computer Fraud and Abuse Act (CFAA), the UK’s Computer Misuse Act, and Europe’s GDPR regulations. Companies that don’t secure their networks properly can also face fines and lawsuits if customer data gets exposed.

That said, not every MITM-style interception is against the law. Penetration testers (the good guys) use controlled MITM attacks to find security weaknesses before criminals do. Banks and law enforcement agencies also legally intercept data for fraud investigations or national security cases—but only when they have the right approvals.

The challenge is knowing where to draw the line. Tight security is necessary, but crossing into unnecessary surveillance can bring its own set of legal and ethical problems.

Frequently asked questions

Can a VPN protect against MITM attacks?

A VPN encrypts traffic, making it harder for attackers to intercept data. However, it won’t prevent attacks that originate from infected devices or compromised networks.

Can an MITM attack be performed on encrypted connections?

Yes, if an attacker successfully hijacks SSL/TLS encryption using techniques like SSL hijacking or HTTPS stripping.

Can mobile devices be targeted in an MITM attack?

Yes, especially over public Wi-Fi or through malicious apps. Attackers can intercept mobile traffic just as they do with desktops.

Does AI help in detecting MITM attacks?

AI-driven security tools can identify unusual traffic patterns, flagging potential MITM attempts faster than manual monitoring.

Are MITM attacks common?

Yes, particularly in environments with poor security hygiene, unencrypted communications, and unsecured public networks.

How do I know if I’ve been targeted by an MITM attack?

Warning signs include HTTPS errors, unexpected login activity, website redirects, or network slowdowns. If sensitive data is compromised without an obvious cause, MITM should be considered.

Can an MITM attack happen on a secured corporate network?

Yes, if an attacker gains access to an internal system, exploits outdated encryption, or uses compromised IoT devices. Even secure networks can be vulnerable to insider threats.

Are banking apps vulnerable to MITM attacks?

Most modern banking apps use certificate pinning and end-to-end encryption, which make MITM attacks difficult. However, attackers can still intercept transactions if they control the device or trick users into installing malware.

Can an MITM attack be carried out over Bluetooth?

Yes, Bluetooth MITM attacks can intercept data if encryption is weak or authentication is bypassed. Some attacks, like BlueBorne, allow attackers to exploit Bluetooth vulnerabilities remotely.

Can attackers perform MITM attacks on encrypted messaging apps?

If an app uses true end-to-end encryption (E2EE), an MITM attacker cannot read messages. However, compromised devices or social engineering can still expose private conversations.

What’s the difference between an MITM attack and a replay attack?

An MITM attack actively intercepts and alters communication, while a replay attack captures and resends legitimate data, like login credentials, to gain unauthorized access.

Do MITM attacks require physical proximity?

Some, like Wi-Fi eavesdropping, require the attacker to be nearby, but others, like DNS spoofing or SSL stripping, can happen remotely.

Meter’s role in preventing MITM attacks

A man-in-the-middle attack relies on weak security, but Meter’s advanced security solutions make interception far more difficult. We combine firewalls, VPNs, and encryption with real-time threat detection to block unauthorized access.

A zero-trust framework enforces strict security policies, while our fully managed network handles everything from installation to ongoing protection. With Meter’s vertically integrated approach, businesses get a secure, scalable network without added complexity.

Why a business should choose Meter:

• Vertically integrated: Meter-built access points, switches, and security appliances create a cohesive system.
• Hassle-free installation: Our team handles the brunt of the work, from planning to maintenance.
• Automated-powered insights: The Meter dashboard provides deep visibility and control over network security.
• OpEx pricing: A simple monthly fee covers everything, including upgrades and expansions.
• Network protection: DNS security defends against spoofing and interception, keeping business communications secure.

To see how Meter can secure your network, schedule a demo. 

For additional answers to your networking questions, check out our blog.