What Is Fast Flux and Why Attackers Use It
Fast Flux is a DNS evasion technique that helps cybercriminals hide their infrastructure by rapidly rotating IP addresses and even name servers associated with a domain. A single malicious domain may resolve to a new IP address every few minutes, making it a moving target.
Attackers often leverage botnets of compromised machines to act as proxies, keeping their command-and-control (C2) or phishing servers one step ahead of defenders. While not new, Fast Flux remains effective, and CISA recently warned that attackers – from cybercriminals to APT groups – are actively using it. Read on to understand how Fast Flux works, and how Bowtie mitigates it by design.
Fast Flux and Centralized Network Security
For organizations looking to modernize their network security stack, SASE or SSE platforms become an attractive option. The promise of rapid deployment and simplified management offers the same promise of the cloud, but security leaders must consider all security implications.
Traditional SASE platforms rely on centralized, IP-based filtering. These solutions maintain blocklists of known malicious IPs, but in a Fast Flux scenario, the IPs rotate faster than blocklists can update. By the time a new IP is identified and blocked, the attacker has already moved on.
This 'whack-a-mole' problem is exacerbated by short DNS TTLs and globally distributed IPs, which traditional cloud-based filters struggle to process in time. Without DNS inspection, some SASE platforms may never see the malicious name resolution at all.
How Bowtie’s DNS-Based Blocking Stops Fast Flux
Bowtie’s architecture takes a different approach, focusing on domain name resolution instead of chasing IP addresses. The Bowtie client blocks known-bad domains at the DNS layer – if a domain is on the deny list, it won’t resolve, period.
Even if the domain rotates to a new IP every five minutes, the client and controller already know not to trust the name. The controller performs DNS queries just like the client, respecting the TTLs and blocking any number of IPs associated with that domain. This makes Fast Flux irrelevant—Bowtie cuts off the connection before any traffic begins.
In addition, the warning calls out the swapping of authorities in addition to records as an attempt to confuse tooling. Here again, Bowtie remains a step ahead by never consulting a second source.
DNS Observability Is Critical
Having complete visibility into DNS activity on a device is critically essential to remaining resilient against Fast Flux. Control and visibility remain cornerstones of any security program, and complete visibility is often difficult to achieve.
Bowtie quickly provides full activity visibility in scenarios where you might not otherwise have that visibility – namely, operating in ‘split-tunnel’ mode or in ‘no-tunnel’ scenarios. With real-time integrations into existing SIEM infrastructure, Bowtie enables proactive threat and IoC discovery.
A Decentralized Architecture for Stronger Security
Bowtie’s DNS-based blocking works in tandem with its ‘decentralized SaaS’ model. Unlike traditional cloud SASE vendors, Bowtie doesn’t route traffic through a vendor-controlled cloud or require sharing sensitive data.
Instead, Bowtie operates as an ‘Edge Security Fabric’ where the deployment components are the same as traditional SASE solutions, but without Bowtie in the middle, ensuring true end-to-end encryption. No decryption or inspection happens in third-party infrastructure. You keep control of your keys, your policies, and your traffic, all while benefiting from automated updates and global policy management. This architecture reduces risk, improves privacy, and keeps enforcement close to the user or workload, where it’s most effective.
Conclusion
Fast Flux succeeds by staying ahead of traditional defenses that rely on slow-moving, centralized IP blocklists. Organizations should consider how existing or future solutions may inadvertently increase the attack surface. If you’re interested in seeing what we’ve described in action or learning more about Bowtie, please reach out.