DHCP Attack Definition

A DHCP attack is a network attack that targets the Dynamic Host Configuration Protocol (DHCP), which manages how devices receive IP addresses and basic network settings. By manipulating this system, an attacker can disrupt normal network operations or take advantage of how devices communicate. The attack breaks the trust between devices and the network infrastructure. Once that trust is compromised, attackers can block connections, redirect traffic, or position themselves to observe or control data moving across the network.

How a DHCP Attack Works

When a device connects to a network, it automatically asks a DHCP server for an IP address and configuration details, like the default gateway and DNS server. Under normal conditions, a trusted DHCP server responds with accurate information so the device can communicate properly.

During a DHCP attack, an attacker exploits this automatic process. They may flood the network with fake DHCP requests or introduce a malicious DHCP server that responds faster than the legitimate one. Because devices typically accept the first valid response they receive, they may unknowingly apply harmful network settings.

As a result, devices can lose connectivity, be redirected through attacker-controlled systems, or send traffic to fake gateways or DNS servers. This can lead to service disruption, traffic monitoring, or man-in-the-middle attacks.

Common Types of DHCP Attacks

• DHCP starvation attack: Floods the network with fake requests until all available IP addresses are used up, preventing legitimate devices from connecting.
• Rogue DHCP server attack: Introduces a fake DHCP server to hand out incorrect network settings and redirect or disrupt normal traffic.
• DHCP spoofing: Sends false DHCP responses to trick devices into accepting malicious configuration details.
• Man-in-the-Middle via DHCP: Manipulates DHCP settings to route traffic through the attacker’s system, allowing them to monitor or manipulate data in transit.
• DHCP packet flooding: Overwhelms the network infrastructure by sending large volumes of DHCP packets.
• Denial of Service (DoS): Uses DHCP abuse to block devices from receiving valid network settings, effectively cutting off internet access and network availability.
• Malicious network control: Exploits DHCP to force devices onto attacker-controlled routes or services, giving the attacker influence over how and where network traffic flows.

DHCP Attack vs ARP Spoofing Attacks

DHCP attacks and ARP spoofing attacks both target network traffic, but they operate at different stages. A DHCP attack interferes with how devices receive IP addresses and network settings when they first connect, allowing attackers to block access or redirect traffic early on. ARP spoofing occurs after devices are already connected and works by tricking them into sending data to the attacker instead of the correct destination.

How to Prevent a DHCP Attack

• Enable DHCP snooping to block rogue DHCP servers.
• Restrict network access to prevent unauthorized connections.
• Monitor DHCP traffic for suspicious activity.
• Segment the network to limit the spread of the attack.
• Keep network devices up to date with the latest security patches.
• Disable unused ports to reduce attack surfaces.

Read More

• What Is a DHCP Proxy?
• What Is a Dictionary Attack?
• What Is a Drive-By Attack?

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