T1568.003 DNS Calculation

Adversaries may perform calculations on addresses returned in DNS results to determine which port and IP address to use for command and control, rather than relying on a predetermined port number or the actual returned IP address. A IP and/or port number calculation can be used to bypass egress filtering on a C2 channel.(Citation: Meyers Numbered Panda)

One implementation of DNS Calculation is to take the first three octets of an IP address in a DNS response and use those values to calculate the port for command and control traffic.(Citation: Meyers Numbered Panda)(Citation: Moran 2014)(Citation: Rapid7G20Espionage)

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VERIS Mappings

Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
action.hacking.variety.Evade Defenses Modification of the action (rather than the system, as in 'Disable controls') to avoid detection. related-to T1568.003 DNS Calculation
action.malware.variety.Backdoor or C2 Malware creates a remote control capability, but it's unclear if it's a backdoor for hacking or C2 for malware. Parent of 'C2' and 'Backdoor'. related-to T1568.003 DNS Calculation
action.malware.variety.C2 Malware creates Command and Control capability for malware. Child of 'Backdoor or C2'. related-to T1568.003 DNS Calculation