What is IP spoofing?

How IP spoofing works

IP addresses are a crucial part of how the internet functions. Every packet sent over the internet has an IP header. This header contains information about the source of the packet, its destination, and how the packet should reach its destination (routing).

Without IP headers, navigating the web would be virtually impossible. However, IP address spoofing exploits our dependence on IP headers. Spoofing makes it hard to tell whether a packet comes from a legitimate source address. It scrambles our ability to separate legitimate and fake traffic.

IP spoofing works by modifying data in the IP address header. Attackers gain access to trusted connections between two devices or websites. To achieve this they need a trusted IP address that bypasses network filters.

After gaining access and fooling network defenses, attackers use packet sniffers or Address Resolution Protocol scans to detect network traffic flows. They intercept traffic, decode the IP header, and insert information of their own.

Why does IP spoofing matter?

IP address spoofing is a significant cybersecurity threat linked to network outages and data theft risks.

Attackers can use IP spoofing to bypass authentication measures on the targeted computer system. Security tools may fail to detect spoofed IPs, allowing lateral movement inside network boundaries.

IP spoofing is critical in distributed denial-of-service attacks (DDoS). DDoS attacks overwhelm network servers with seemingly legitimate requests, eventually damaging business operations.

Spoofing plays a role in interception attacks, too. IP spoofing allows man-in-the-middle attackers to masquerade as trusted contacts—enabling them to harvest data and redirect victims to malicious sites.

Types of IP spoofing

There are different ways to spoof IP addresses, and companies must consider each technique in their security strategies.

The first distinction is between blind and non-blind spoofing techniques:

• Blind spoofing. Attackers without network access send a series of requests to target servers to learn IP address sequences and assemble spoofed packets. The target responds with a number sequence that attackers can reassemble and use in spoofing operations.
• Non-blind spoofing. Non-blind spoofing applies when attackers are on the same subnet as their victims. In that case, spoofers know the packet sequence and can sniff IP packets to extract address data.

When they determine packet sequences and understand how to re-label data packets, attackers can leverage their position in several ways. IP spoofing methods include:

• DDoS attacks. Attackers flood their victims with spoofed IP packets. Servers interpret packets as legitimate and they respond normally. At sufficient volume, a DDoS attack overloads processing capacity, taking networks offline.
• Man-in-the-middle attacks (MITM). MITM attacks use IP spoofing to intercept traffic without detection. Attackers position themselves between two communicating devices or users. Spoofing allows them to decode or alter IP packets without being detected.
• Botnet masking. Botnets can orchestrate a DDoS attack but are also used in surveillance and crypto-jacking attacks. Botnet controllers use IP spoofing to conceal the identity of their bots. This makes botnets harder to detect and remove.
• Hybrid spoofing attacks. Some attacks combine IP address spoofing with Domain Name System (DNS) spoofing. This combination lets them fool targets into visiting fake websites, which they use to inject malware or launch other attacks.

IP spoofing case studies

How do IP spoofing attacks happen in the real world? There are many examples of IP spoofing in the wild, often with severe consequences for victims.

In 2018, the coding platform GitHub suffered a massive DDoS attack. Cybercriminals spoofed legitimate GitHub IP addresses and flooded the site's database servers with incoming packets. At the attack's peak, the server response rate was 50 times its normal level, resulting in a 10-minute outage.

In 2020, Google fell victim to a crippling spoofing attack. Chinese attackers used a UDP amplification method to spoof up to 2.5Tbps of traffic directed at Google servers. At the time, the peak rate was four times the previous record—a sign of how quickly spoofing attacks can grow.

Overall, cybersecurity statistics suggest DDoS attacks are becoming more serious, in terms of both frequency and peak power. IP spoofing plays a critical role in many DDoS attack methods. Companies need robust protective measures to detect and prevent spoofing techniques.

How can you detect IP spoofing?

In cybersecurity terms, IP spoofing presents two challenges: detection and prevention.

Detection is often challenging. Skilled spoofers hide their tracks and operate at the OSI network layer, making it hard to tell whether packet headers are fake before attacks occur. However, security teams have some tools to discover active IP spoofing operations.

Reliable packet filtering firewalls are critically important. Filtering has two components: ingress filtering and egress filtering.

• Ingress filtering checks incoming packets for suspicious packet headers. Firewalls match packet headers with IP addresses listed in Access Control Lists (ACLs). Any unknown or unauthorized IPs are blocked.
• Egress filtering checks packets leaving the network. Firewalls monitor traffic for IP headers that don't match addresses on the internal network. This won't catch external spoofing attacks, but it does help detect spoofing occurring inside the network.

Additionally, companies can use TCP sequence analysis to check packet sequences. Spoofed sequences may not match exactly with those generated by network servers. Intrusion Detection Systems (IDS) may also help by checking for unusual IP address behavior.

Reverse Path Forwarding (RPF) also detects fake packets by tracing the route from the source address to the network server. If packets don't follow the optimal route, this may be evidence of spoofing attacks.

Ways to protect against IP spoofing

Detection is reactive. Comprehensive protection against IP address spoofing requires a proactive approach that manages user access and makes spoofing as difficult as possible.

Protective measures include:

• Controlling access with robust authentication. Use multi-factor authentication to ensure only authorized users access network resources. Keep IP spoofing attackers outside the network boundary to limit their attack potential.
• Implement network monitoring solutions. IP spoofing often starts with anomalous behavior or access patterns. Scan for unusual activity and use packet filtering firewalls to uncover inconsistencies in packet headers as they cross the network boundary.
• Use strong encryption. Encrypted network traffic is far harder to spoof. Attackers must decrypt packets before decoding and reassembling headers. Use a dependable Business VPN and encrypt data in transit throughout the network.
• Employ Network Access Controls (NAC). Tightly control how devices and users access the network. Use Device Posture Checks to screen each computer system and allow authorized devices. Enforce security policies to block unsafe connections.
• Regularly update internet-facing applications. Software vulnerabilities open the door to IP address spoofing attacks. Routinely update operating systems, device firmware, and web applications. Update security tools to reflect the latest threat intelligence. Applying security patches to router firmware is essential. Vulnerabilities in networking equipment can be exploited for spoofing attacks, making firmware updates a vital defense mechanism.

IP spoofing is a significant threat to business operations and data security. Strengthen your defenses by controlling network access and filtering traffic for suspicious activity.