Adversaries may poison Address Resolution Protocol (ARP) caches to position themselves between the communication of two or more networked devices. This activity may be used to enable follow-on behaviors such as Network Sniffing or Transmitted Data Manipulation.
The ARP protocol is used to resolve IPv4 addresses to link layer addresses, such as a media access control (MAC) address.(Citation: RFC826 ARP) Devices in a local network segment communicate with each other by using link layer addresses. If a networked device does not have the link layer address of a particular networked device, it may send out a broadcast ARP request to the local network to translate the IP address to a MAC address. The device with the associated IP address directly replies with its MAC address. The networked device that made the ARP request will then use as well as store that information in its ARP cache.
An adversary may passively wait for an ARP request to poison the ARP cache of the requesting device. The adversary may reply with their MAC address, thus deceiving the victim by making them believe that they are communicating with the intended networked device. For the adversary to poison the ARP cache, their reply must be faster than the one made by the legitimate IP address owner. Adversaries may also send a gratuitous ARP reply that maliciously announces the ownership of a particular IP address to all the devices in the local network segment.
The ARP protocol is stateless and does not require authentication. Therefore, devices may wrongly add or update the MAC address of the IP address in their ARP cache.(Citation: Sans ARP Spoofing Aug 2003)(Citation: Cylance Cleaver)
Adversaries may use ARP cache poisoning as a means to intercept network traffic. This activity may be used to collect and/or relay data such as credentials, especially those sent over an insecure, unencrypted protocol.(Citation: Sans ARP Spoofing Aug 2003)
Detect ARP Cache Poisoning Across Linux, Windows, and macOS
Encrypt Sensitive Information: Protect sensitive information at rest, in transit, and during processing by using strong encryption algorithms. Encryption ensures the confidentiality and integrity of data, preventing unauthorized access or tampering. This mitigation can be implemented through the following measures:
Encrypt Data at Rest:
Encrypt Data in Transit:
Encrypt Backups:
Encrypt Application Secrets:
Database Encryption:
Network Intrusion Prevention: Use intrusion detection signatures to block traffic at network boundaries.
User Training: User Training involves educating employees and contractors on recognizing, reporting, and preventing cyber threats that rely on human interaction, such as phishing, social engineering, and other manipulative techniques. Comprehensive training programs create a human firewall by empowering users to be an active component of the organization's cybersecurity defenses. This mitigation can be implemented through the following measures:
Create Comprehensive Training Programs:
Use Simulated Exercises:
Leverage Gamification and Engagement:
Incorporate Security Policies into Onboarding:
Regular Refresher Courses:
Emphasize Real-World Scenarios:
Disable or Remove Feature or Program: Disable or remove unnecessary and potentially vulnerable software, features, or services to reduce the attack surface and prevent abuse by adversaries. This involves identifying software or features that are no longer needed or that could be exploited and ensuring they are either removed or properly disabled. This mitigation can be implemented through the following measures:
Remove Legacy Software:
Disable Unused Features:
Control Applications Installed by Users:
Remove Unnecessary Services:
Restrict Add-ons and Plugins:
Limit Access to Resource Over Network: Restrict access to network resources, such as file shares, remote systems, and services, to only those users, accounts, or systems with a legitimate business requirement. This can include employing technologies like network concentrators, RDP gateways, and zero-trust network access (ZTNA) models, alongside hardening services and protocols. This mitigation can be implemented through the following measures:
Audit and Restrict Access:
Deploy Secure Remote Access Solutions:
Disable Unnecessary Services:
Network Segmentation and Isolation:
Monitor and Log Access:
Tools for Implementation
File Share Management:
Secure Remote Access:
Service and Protocol Hardening:
Network Segmentation:
Filter Network Traffic: Employ network appliances and endpoint software to filter ingress, egress, and lateral network traffic. This includes protocol-based filtering, enforcing firewall rules, and blocking or restricting traffic based on predefined conditions to limit adversary movement and data exfiltration. This mitigation can be implemented through the following measures:
Ingress Traffic Filtering:
Egress Traffic Filtering:
Protocol-Based Filtering:
Network Segmentation:
Application Layer Filtering: