Dynamic Resolution: Fast Flux DNS (T1568.001)
Tactic: Command and Control · Platforms: Linux, macOS, Windows, ESXi
The interactive view maps 1 detection strategy, 3 threat groups, 3 software entries to this technique, alongside D3FEND countermeasures and data-component coverage.
Sub-technique of Dynamic Resolution (T1568).
Overview
Adversaries may use Fast Flux DNS to hide a command and control channel behind an array of rapidly changing IP addresses linked to a single domain resolution. This technique uses a fully qualified domain name, with multiple IP addresses assigned to it which are swapped with high frequency, using a combination of round robin IP addressing and short Time-To-Live (TTL) for a DNS resource record.
The simplest, "single-flux" method, involves registering and de-registering an addresses as part of the DNS A (address) record list for a single DNS name. These registrations have a five-minute average lifespan, resulting in a constant shuffle of IP address resolution.
In contrast, the "double-flux" method registers and de-registers an address as part of the DNS Name Server record list for the DNS zone, providing additional resilience for the connection. With double-flux additional hosts can act as a proxy to the C2 host, further insulating the true source of the C2 channel.