Introduction
APIs and internal networks are often treated as safe by default. However, attacks like ARP spoofing prove that trusted networks can still be abused from the inside. Offices, corporate Wi-Fi, and shared environments frequently rely on assumptions that attackers are quick to exploit.
One of the most effective ways attackers exploit this trust is through ARP spoofing, also known as network poisoning. Instead of breaking into systems from the outside, attackers quietly intercept traffic from within the network itself.
ARP poisioning attacks are dangerous because they often leave no obvious signs. Users stay logged in, applications continue working, and data keeps flowing. However, attackers may be watching everything in between.
This blog explains ARP poisioning and network poisoning in a simple, human-friendly way and shows why trusted networks are not always safe.
What Is ARP Spoofing and Network Poisoning?
This is a network attack where an attacker tricks devices into sending traffic to the wrong destination.
Let’s break this down clearly.
- ARP (Address Resolution Protocol) maps IP addresses to physical MAC addresses
- MAC address uniquely identifies a device on a network
- Spoofing means pretending to be something you are not
In a normal network, devices use ARP to ask:
“Who has this IP address?”
The correct device replies, and communication continues normally.
In an ARP poisoning attack, the attacker sends fake ARP replies. As a result, devices believe the attacker’s machine is the router or another trusted system.
Once this happens, network traffic flows through the attacker, not directly between devices.
ARP poisioning exists because the Address Resolution Protocol was designed without authentication, allowing devices to accept ARP replies without verification. Read more .
How ARP Spoofing Attacks Work
ARP spoofing attacks follow a predictable pattern.
Step 1: Attacker gains network access
The attacker connects to the target network. This could happen through:
- Compromised Wi-Fi access
- Rogue devices plugged into a switch
- Infected internal machines
Step 2: ARP cache poisoning begins
The attacker sends forged ARP messages claiming:
- “I am the router”
- “I am the target system”
These messages update the ARP cache of other devices.
Step 3: Traffic is redirected
Victim devices start sending traffic to the attacker instead of the legitimate router or server.
Step 4: Man-in-the-Middle established
The attacker silently forwards traffic to the real destination to avoid detection.
Meanwhile, they can:
- Read unencrypted data
- Modify packets
- Inject malicious responses
Step 5: Exploitation escalates
Once traffic interception is stable, attackers may:
- Steal credentials
- Hijack sessions
- Inject malware
- Redirect users to fake services
Why Network Poisoning Is So Effective
These attack succeeds because it abuses implicit trust inside networks.
ARP has no authentication
Devices trust ARP replies by default.
Internal traffic is rarely monitored
Many organisations focus security on perimeter threats.
Attack traffic looks normal
ARP packets are common and rarely flagged.
Encryption is not universal
Legacy protocols and internal services may still send data in plain text.
Users assume internal safety
This false sense of security reduces suspicion.
ARP Spoofing vs External Network Attacks
ARP based attacks differs significantly from internet-based attacks.
- External attacks target exposed services
- ARP spoofing targets internal trust relationships
This makes detection harder and impact broader.
Real-World Example
Imagine an employee connects to corporate Wi-Fi during a busy workday. An attacker joins the same network using stolen credentials.
Within minutes, the attacker launches ARP spoofing. The victim’s laptop believes the attacker is the default gateway.
As the employee logs into internal dashboards and email systems, session tokens and credentials pass through the attacker’s machine. Even HTTPS traffic can be manipulated through downgrade or injection techniques if additional controls are missing.
By the end of the day, the attacker has harvested credentials without triggering any alarms.
This scenario reflects how ARP spoofing quietly operates in real environments.
Why ARP Spoofing Is Hard to Detect
ARP spoofing often goes unnoticed for long periods.
No visible service disruption
Traffic still reaches its destination.
No authentication failures
Users log in normally.
Minimal logging
ARP activity is rarely logged by default.
Short-lived attacks
Attackers can poison caches briefly and leave.
Lack of endpoint awareness
Most devices trust ARP responses blindly.
Impact on Businesses / Individuals
For Businesses
- Credential theft
- Session hijacking
- Internal data exposure
- Malware injection
- Compliance violations
- Loss of trust in internal systems
For Individuals
- Account compromise
- Privacy invasion
- Credential reuse attacks
- Financial fraud
- Identity theft
How to Prevent ARP Spoofing and Network Poisoning
Defending against these attacks requires layered controls.
Use encrypted protocols everywhere
Encryption limits what attackers can read or modify.
Enable dynamic ARP inspection
Network devices can validate ARP packets.
Segment networks
Smaller segments reduce attack reach.
Implement zero-trust principles
Never assume internal traffic is safe.
Monitor ARP activity
Unusual ARP behaviour should trigger alerts.
Secure Wi-Fi access
Strong authentication limits attacker entry.
Harden endpoint security
Endpoint protection can detect suspicious behaviour.
Why ARP Spoofing Still Matters Today
Despite being an old technique, ARP poisioning remains relevant. Cloud environments, shared networks, and remote work have increased internal attack surfaces.
As long as ARP remains unauthenticated, attackers will continue abusing it. Therefore, organisations must treat internal networks with the same caution as external ones.
Conclusion
ARP poisioning and network poisoning show that trust inside a network can be dangerous. By intercepting traffic silently, attackers bypass traditional security boundaries and operate without detection.
Understanding how ARP poisioning works helps organisations design safer networks and reduce blind trust. At eSHIELD IT Services, we help businesses identify internal network risks and implement modern security strategies that protect data at every layer.
Ultimately, secure networks are built not on trust, but on verification.
FAQ
What is ARP spoofing?
It’s an attack that redirects network traffic using fake ARP messages.
Is ARP spoofing the same as MITM?
ARP spoofing often enables man-in-the-middle attacks.
Can ARP spoofing work on Wi-Fi?
Yes, especially on shared networks.
Does HTTPS prevent ARP spoofing?
It limits damage but does not stop interception.
Is ARP spoofing detectable?
Yes, with proper network monitoring.
Are home networks vulnerable?
Yes, especially poorly secured Wi-Fi.
Can attackers steal passwords using ARP spoofing?
Yes, particularly from unencrypted traffic.
Is ARP spoofing illegal?
Yes, when used without authorisation.
Do modern networks still use ARP?
Yes, ARP remains widely used.
Who should defend against ARP spoofing?
Network, security, and IT teams together.
