In the modern digital world, network security is one of the top priorities for organizations. While firewalls, antivirus software, and intrusion detection systems protect us from many threats, attackers often exploit basic network protocols. One such attack is ARP spoofing, also known as ARP poisoning. Understanding this attack and how a Security Operations Center (SOC) detects it is crucial for cybersecurity professionals.

Understanding ARP (Address Resolution Protocol)

ARP is a protocol used in IPv4 networks to map logical addresses (IP) to physical addresses (MAC). Every time a device communicates within a local network, it needs to know the MAC address of the recipient.

The ARP process is simple:

  • A device broadcasts an ARP request asking, “Who has this IP?”

  • The device with the requested IP responds with its MAC address.

  • The sender stores this mapping in its ARP table for future communications.

This system is trust-based, which is what makes it vulnerable to attacks like ARP spoofing.

What is ARP spoofing?

ARP spoofing, also called ARP poisoning, is a network attack where an attacker tricks devices into sending data to them instead of the intended device. ARP, a protocol that matches IP addresses to physical MAC addresses, normally trusts all responses, which makes this possible. By sending fake ARP messages, attackers can intercept, modify, or block network traffic. This allows them to steal sensitive information or disrupt communication. SOC analysts detect it by monitoring network traffic, checking for unusual IP-to-MAC mappings, and using tools like Wireshark or IDS systems.

How SOC Detects ARP Spoofing

SOC analysts monitor the network for signs of ARP spoofing using a combination of real-time monitoring, log analysis, and alerts. Here are the key steps:

1. Monitoring ARP Tables

Analysts watch for duplicate IP-to-MAC mappings in ARP tables. If multiple MAC addresses are associated with the same IP, it could indicate ARP spoofing.

2. Analyzing Network Traffic

Using tools like Wireshark, analysts capture ARP traffic and inspect packets for irregularities. Frequent ARP replies from the same device or unexpected IP-MAC combinations are red flags.

3. Correlating Logs

SOC teams cross-reference ARP activity with DHCP logs, switch MAC tables, and endpoint security alerts. Correlation helps determine whether the behavior is malicious or due to legitimate network changes.

4. Using IDS/IPS Alerts

Intrusion Detection Systems (IDS) like Snort or Suricata can detect ARP spoofing patterns and generate alerts for SOC analysts.

Conclusion

ARP spoofing is a deceptively simple yet potentially dangerous network attack that can allow attackers to intercept, modify, or block network traffic. Since ARP relies on trust, devices can be easily tricked into sending data to the wrong recipient, putting sensitive information at risk. SOC analysts play a critical role in detecting and mitigating ARP spoofing by monitoring ARP tables, analyzing network traffic, correlating logs, and leveraging IDS/IPS alerts. Understanding how ARP spoofing works and how to detect it is essential for maintaining network security and ensuring the integrity of organizational data. With the right tools, vigilance, and best practices, SOC teams can effectively protect networks from these attacks