Fast Flux: A Growing Threat to Critical Infrastructure

A recent cybersecurity advisory (AA25-093A) from CISA and other agencies highlights the increasing threat posed by the "fast flux" technique. This method, employed by cybercriminals and nation-state actors, allows malicious servers to hide by rapidly changing their DNS records. This makes it extremely difficult to track and block their activities, posing a significant risk to critical infrastructure.

Double flux technique. 

What is Fast Flux?

Fast flux is a DNS evasion technique where malicious actors constantly change the IP addresses associated with a domain name. This rapid rotation makes it challenging for security systems to identify and block malicious servers, as they appear to be constantly shifting.

Why is it a threat?

This technique is used to mask various malicious activities, including:

• Phishing campaigns: Hiding the servers hosting fraudulent websites.

• Malware distribution: Obscuring the source of malicious software.

• Botnet command and control: Concealing the servers controlling networks of compromised devices.

What can be done?

The advisory urges service providers, especially those using Protective DNS (PDNS), to develop detection and blocking capabilities for fast flux. It also recommends:

• DNS analysis: Monitoring DNS records for suspicious rapid changes.

• Network monitoring: Analyzing network traffic for unusual patterns.

• Threat intelligence: Sharing information about known fast-flux networks.

Collaboration between the government and providers is crucial for implementing scalable solutions and addressing this growing threat to our nation's critical infrastructure.

For more information see https://www.cisa.gov/news-events/cybersecurity-advisories/aa25-093a