| ID | Name |
|---|---|
| T1568.001 | Fast Flux DNS |
| T1568.002 | Domain Generation Algorithms |
| T1568.003 | DNS Calculation |
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.[1][2][3]
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.[3]
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.
| ID | Name | Description |
|---|---|---|
| S1025 | Amadey | |
| G0047 | Gamaredon Group |
Gamaredon Group has used fast flux DNS to mask their command and control channel behind rotating IP addresses.[5][6][7] Additionally, Gamaredon Group has used a low-frequency variant of the single-flux method.[8] |
| S0032 | gh0st RAT |
gh0st RAT operators have used dynamic DNS to mask the true location of their C2 behind rapidly changing IP addresses.[9] |
| G0045 | menuPass |
menuPass has used dynamic DNS service providers to host malicious domains.[10] |
| S0385 | njRAT | |
| G0092 | TA505 |
TA505 has used fast flux to mask botnets by distributing payloads across multiple IPs.[12] |
This type of attack technique cannot be easily mitigated with preventive controls since it is based on the abuse of system features.
| ID | Name | Analytic ID | Analytic Description |
|---|---|---|---|
| DET0485 | Detection Strategy for Dynamic Resolution using Fast Flux DNS | AN1331 |
Identify repeated DNS resolutions where the same domain name returns multiple IPs in short succession, combined with low TTL values and high query volume from unusual processes. Correlate with process lineage (e.g., Office apps spawning abnormal DNS lookups). |
| AN1332 |
Monitor resolver logs and auditd events for domains resolving to a rotating set of IPs within very short TTL intervals. Correlate high query rates from non-browser applications (e.g., python, curl). |
||
| AN1333 |
Use unified logs to identify processes issuing repeated DNS queries where the resolved IP addresses change frequently within very short TTL values. Correlate with outbound network traffic to validate C2-like patterns. |
||
| AN1334 |
Monitor ESXi syslog and esxcli outputs for abnormal DNS resolver behavior, such as frequent domain-to-IP changes or unauthorized modifications of DNS settings used by management agents. Correlate domain lookups with short TTL values. |