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.^[1]

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.^[1],[2],[3]

References

1. Meyers, A. (2013, March 29). Whois Numbered Panda. Retrieved January 14, 2016.
2. Moran, N., Oppenheim, M., Engle, S., & Wartell, R.. (2014, September 3). Darwin’s Favorite APT Group [Blog]. Retrieved November 12, 2014.
3. Rapid7. (2013, August 26). Upcoming G20 Summit Fuels Espionage Operations. Retrieved March 6, 2017.

Saistītie uzdevumi

• MITREATTACK -

  EN: MITRE ATT&CK®, https://attack.mitre.org/. © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. License: The MITRE Corporation (MITRE) hereby grants you a non-exclusive, royalty-free license to use ATT&CK® for research, development, and commercial purposes. Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy. See the Terms of Use for the disclaimers. ATT&CK® is a registered trademark of The MITRE Corporation. Converted into the GRCA format.

  DE: MITRE ATT&CK®, https://attack.mitre.org/. © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. MITRE erlaubt die Nutzung für Forschung, Entwicklung und kommerzielle Zwecke, wenn jede Kopie den Urheberrechtsvermerk und die Lizenz enthält; maßgeblich ist der englische Wortlaut der Lizenz oben und die Terms of Use mit den Haftungsausschlüssen. ATT&CK® ist eine eingetragene Marke der MITRE Corporation. In das GRCA-Format umgewandelt.