IRDP Spoofing Attack Explained | ICMP Redirect Vulnerabilities & Prevention (2025 Guide)

Learn what IRDP spoofing is, how attackers use ICMP redirect messages for man-in-the-middle attacks, and how to prevent them. Includes tools, commands, and real-world use cases.

Penetration Testing Jul 3, 2025 20 Add to Reading List

What Is IRDP Spoofing?
How Does IRDP Spoofing Work?
Real-World Example of IRDP Spoofing
Tools Used in IRDP Spoofing
How to Prevent IRDP Spoofing
Difference Between IRDP and ARP Spoofing
Why IRDP Spoofing Is Still Relevant in 2025
Conclusion
Frequently Asked Questions (FAQs)

As cyberattacks grow in sophistication, attackers are increasingly leveraging lesser-known network protocols to infiltrate systems. One such technique is IRDP spoofing, a method of network-based redirection attacks using the Internet Router Discovery Protocol (IRDP). Though less discussed than DNS or ARP spoofing, IRDP spoofing can lead to serious security breaches—especially in misconfigured or legacy environments.

This blog explores what IRDP spoofing is, how it works, and how to defend against it with real-world use cases and prevention tips.

What Is IRDP Spoofing?

IRDP (ICMP Router Discovery Protocol) is part of the ICMP suite (Internet Control Message Protocol), designed to allow hosts to discover routers on their network. Under normal operations, a host listens for ICMP Router Advertisement messages to identify the best gateway.

In IRDP spoofing, a malicious attacker sends forged ICMP Router Advertisement packets, tricking devices into routing their traffic through a compromised or unauthorized router. This opens the door to man-in-the-middle (MITM) attacks, data interception, or network redirection.

How Does IRDP Spoofing Work?

IRDP spoofing exploits trust-based mechanisms in the ICMP protocol. Here's a step-by-step breakdown:

Step 1: Scanning the Network

The attacker scans the local network to identify active hosts and the default gateway.

Step 2: Sending Fake Advertisements

Using tools like nemesis, scapy, or hping3, the attacker sends spoofed ICMP Router Advertisement packets advertising themselves as a default gateway.

Step 3: Redirection

Unsuspecting clients accept the advertisement and change their routing table, setting the attacker's IP as the default gateway.

Step 4: Man-in-the-Middle or Denial of Service

The attacker can:

Forward the traffic (MITM),
Drop it (DoS),
Alter or sniff packets (data breach).

Real-World Example of IRDP Spoofing

An attacker on a public Wi-Fi network uses a spoofed ICMP advertisement to reroute corporate employee traffic through their laptop. Sensitive credentials and emails are intercepted in plain text due to misconfigured HTTPS settings.

Tools Used in IRDP Spoofing

Tool	Description	Usage
Scapy	Python-based tool for crafting packets	`scapy.send(IP(dst="target")/ICMP(type=9, code=0))`
Nemesis	Command-line packet injection tool	`nemesis icmp -d eth0 -S attacker_ip -D target_ip`
Hping3	Network scanning and packet forging	`hping3 --icmp --spoof gateway_ip target_ip`

How to Prevent IRDP Spoofing

1. Disable IRDP on Endpoints and Routers

On Linux:

sudo sysctl -w net.ipv4.conf.all.accept_redirects=0
sudo sysctl -w net.ipv4.conf.all.send_redirects=0

2. Implement Static Routing Where Possible

Use static default routes on critical systems that don’t rely on ICMP discovery.

3. Enable Packet Inspection and IDS/IPS

Security systems like Snort or Suricata can detect and block suspicious ICMP Router Advertisements.

4. Use Secure Network Segmentation

Separate trusted hosts from guest or public devices, minimizing lateral attack surfaces.

5. Apply Router Advertisement Filtering

Enterprise-grade switches and firewalls can block unsolicited router advertisements.

Who Is at Risk?

Legacy Networks: Older systems that rely on IRDP or ICMP are most vulnerable.
Public Wi-Fi Users: Open networks are breeding grounds for spoofing attacks.
Enterprises with Poor ICMP Policies: Misconfigured firewalls allow ICMP messages freely.

Difference Between IRDP and ARP Spoofing

Feature	IRDP Spoofing	ARP Spoofing
Layer	Network (Layer 3)	Data Link (Layer 2)
Protocol Used	ICMP	ARP
Scope	Across subnets	Same subnet
Detectability	Harder to detect	Easier to monitor

Why IRDP Spoofing Is Still Relevant in 2025

Even though most modern OSes discourage IRDP usage, it still exists in legacy systems, IoT networks, and misconfigured cloud deployments. Attackers constantly scan for overlooked protocols—and IRDP spoofing is a prime candidate due to its stealth and impact.

✅ Conclusion: Stay Ahead of Protocol-Level Threats

While IRDP spoofing may not be as common as phishing or ransomware, it’s a low-effort, high-impact tactic for attackers with local access. Security professionals and network admins must audit protocol usage, disable legacy services, and configure systems to reject unauthenticated routing advertisements.

Want to test your network's vulnerability? Try running controlled simulations using ethical red teaming tools and verify if your devices respond to rogue router advertisements.

FAQs

What is IRDP spoofing?

IRDP spoofing is a network attack where a hacker sends fake ICMP Router Advertisement messages to redirect traffic through a malicious device.

Which protocol does IRDP spoofing exploit?

It exploits the ICMP (Internet Control Message Protocol) Router Discovery Protocol (IRDP).

What is the goal of IRDP spoofing?

The goal is to redirect network traffic through an attacker’s machine, enabling data interception or manipulation.

Is IRDP spoofing a Layer 3 attack?

Yes, it operates at Layer 3 (the Network Layer) of the OSI model.

How is IRDP spoofing different from ARP spoofing?

ARP spoofing targets MAC addresses (Layer 2), while IRDP spoofing manipulates routing at the IP layer (Layer 3).

What are ICMP Router Advertisements?

They are ICMP messages used to inform hosts about the presence of routers on the network.

Can IRDP spoofing happen on modern networks?

Yes, especially in environments with misconfigured security settings or legacy systems.

What tools are used for IRDP spoofing?

Tools like Scapy, Nemesis, and Hping3 can be used to craft spoofed ICMP advertisements.

How do attackers perform IRDP spoofing?

They send crafted ICMP messages that trick hosts into updating their routing tables with the attacker's IP.

Can firewalls prevent IRDP spoofing?

Yes, properly configured firewalls can filter or block rogue ICMP Router Advertisement messages.

Is IRDP spoofing detectable?

Yes, using network monitoring and intrusion detection systems like Snort or Suricata.

What operating systems are vulnerable to IRDP spoofing?

Primarily Linux and legacy Windows systems with IRDP enabled or misconfigured.

Does IRDP spoofing require physical access?

No, it can be executed remotely if the attacker is on the same local network or VLAN.

How do I disable IRDP in Linux?

By using sysctl commands to disable accept_redirects and send_redirects.

Why is IRDP still a threat in 2025?

Because many organizations still run outdated systems or fail to audit ICMP configurations.

What is a practical example of IRDP spoofing?

An attacker at a café redirects employee traffic through their laptop using ICMP advertisements.

Can attackers modify data during IRDP spoofing?

Yes, if traffic flows through the attacker’s system, it can be inspected, modified, or dropped.

Is IRDP spoofing a form of MITM attack?

Yes, it’s a specific method of conducting man-in-the-middle (MITM) attacks.

What is the CVSS score of IRDP vulnerabilities?

It depends on the context, but such vulnerabilities can score 7.0 or higher due to impact and reach.

Is IRDP used in modern networks?

Rarely, but it still exists in legacy and embedded systems, making it a hidden risk.

What ports are associated with ICMP messages?

ICMP operates at the IP layer and does not use ports like TCP or UDP.

Can VLANs prevent IRDP spoofing?

They can limit exposure but not eliminate the risk if the attacker is within the same VLAN.

How do you detect IRDP spoofing manually?

Monitor routing table changes or capture ICMP messages with tools like Wireshark.

How does Scapy help in IRDP spoofing?

Scapy allows crafting and sending custom ICMP packets to simulate router advertisements.

Is Nemesis a GUI-based tool?

No, Nemesis is a command-line packet injection tool.

What is the role of Hping3 in IRDP attacks?

Hping3 helps test firewalls and send crafted ICMP packets for reconnaissance or spoofing.

Does IRDP spoofing need user interaction?

No, it works at the protocol level and doesn’t rely on end-user actions.

How do you protect enterprise environments?

Disable IRDP, enforce secure routing policies, monitor for rogue ICMP messages, and use IDS/IPS tools.

Can anti-virus software detect IRDP spoofing?

Not usually; it requires network-level monitoring tools.

What’s the biggest risk of IRDP spoofing?

Unauthorized access to sensitive traffic and potential credential theft or service manipulation.