Application Layer Protocol: DNS

Adversaries may communicate using the Domain Name System (DNS) application layer protocol to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.

The DNS protocol serves an administrative function in computer networking and thus may be very common in environments. DNS traffic may also be allowed even before network authentication is completed. DNS packets contain many fields and headers in which data can be concealed. Often known as DNS tunneling, adversaries may abuse DNS to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.[1][2]

ID: T1071.004
Sub-technique of:  T1071
Tactic: Command And Control
Platforms: Linux, Windows, macOS
Data Sources: DNS records, Netflow/Enclave netflow, Netflow/Enclave netflow, Packet capture, Process monitoring, Process use of network
Contributors: Jan Petrov, Citi
Version: 1.0
Created: 15 March 2020
Last Modified: 27 March 2020

Procedure Examples

Name Description
APT18

APT18 uses DNS for C2 communications.[28]

APT39

APT39 has used remote access tools that leverage DNS in communications with C2.[36]

APT41

APT41 used DNS for C2 communications.[27]

BONDUPDATER

BONDUPDATER can use DNS and TXT records within its DNS tunneling protocol for command and control.[15]

Cobalt Group

Cobalt Group has used DNS tunneling for C2.[29][30][31]

Cobalt Strike

Cobalt Strike uses a custom command and control protocol that can encapsulated in DNS. All protocols use their standard assigned ports.[3]

Cobian RAT

Cobian RAT uses DNS for C2.[7]

Denis

Denis has used DNS tunneling for C2 communications.[9][10][11]

Ebury

Ebury has used DNS requests over UDP port 53 for C2.[16]

FIN7

FIN7 has performed C2 using DNS via A, OPT, and TXT records.[26]

Goopy

Goopy has the ability to communicate with its C2 over DNS.[11]

Helminth

Helminth can use DNS for C2.[17]

HTTPBrowser

HTTPBrowser has used DNS for command and control.[18][19]

Ke3chang

Ke3chang malware RoyalDNS has used DNS for C2.[32]

Matroyshka

Matroyshka uses DNS for C2.[13][14]

NanHaiShu

NanHaiShu uses DNS for the C2 communications.[12]

OilRig

OilRig has used DNS for C2.[33][21][34]

Pisloader

Pisloader uses DNS as its C2 protocol.[5]

PlugX

PlugX can be configured to use DNS for command and control.[18]

POWERSOURCE

POWERSOURCE uses DNS TXT records for C2.[6][8]

POWRUNER

POWRUNER can use DNS for C2 communications.[20][21]

QUADAGENT

QUADAGENT uses DNS for C2 communications.[22]

Remsec

Remsec is capable of using DNS for C2.[23][24][25]

SOUNDBITE

SOUNDBITE communicates via DNS for C2.[4]

TEXTMATE

TEXTMATE uses DNS TXT records for C2.[6]

Tropic Trooper

Tropic Trooper's backdoor has communicated to the C2 over the DNS protocol.[35]

Mitigations

Mitigation Description
Filter Network Traffic

Consider filtering DNS requests to unknown, untrusted, or known bad domains and resources. Resolving DNS requests with on-premise/proxy servers may also disrupt adversary attempts to conceal data within DNS packets.

Network Intrusion Prevention

Network intrusion detection and prevention systems that use network signatures to identify traffic for specific adversary malware can be used to mitigate activity at the network level.

Detection

Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect application layer protocols that do not follow the expected protocol standards regarding syntax, structure, or any other variable adversaries could leverage to conceal data.[37]

Monitor for DNS traffic to/from known-bad or suspicious domains.

References

  1. Palo Alto Networks. (n.d.). What Is DNS Tunneling?. Retrieved March 15, 2020.
  2. Galobardes, R. (2018, October 30). Learn how easy is to bypass firewalls using DNS tunneling (and also how to block it). Retrieved March 15, 2020.
  3. Strategic Cyber LLC. (2017, March 14). Cobalt Strike Manual. Retrieved May 24, 2017.
  4. Carr, N.. (2017, May 14). Cyber Espionage is Alive and Well: APT32 and the Threat to Global Corporations. Retrieved June 18, 2017.
  5. Grunzweig, J., et al. (2016, May 24). New Wekby Attacks Use DNS Requests As Command and Control Mechanism. Retrieved August 17, 2016.
  6. Miller, S., et al. (2017, March 7). FIN7 Spear Phishing Campaign Targets Personnel Involved in SEC Filings. Retrieved March 8, 2017.
  7. Yadav, A., et al. (2017, August 31). Cobian RAT – A backdoored RAT. Retrieved November 13, 2018.
  8. Brumaghin, E. and Grady, C.. (2017, March 2). Covert Channels and Poor Decisions: The Tale of DNSMessenger. Retrieved March 8, 2017.
  9. Dahan, A. (2017, May 24). OPERATION COBALT KITTY: A LARGE-SCALE APT IN ASIA CARRIED OUT BY THE OCEANLOTUS GROUP. Retrieved November 5, 2018.
  10. Shulmin, A., Yunakovsky, S. (2017, April 28). Use of DNS Tunneling for C&C Communications. Retrieved November 5, 2018.
  11. Dahan, A. (2017). Operation Cobalt Kitty. Retrieved December 27, 2018.
  12. F-Secure Labs. (2016, July). NANHAISHU RATing the South China Sea. Retrieved July 6, 2018.
  13. ClearSky Cyber Security and Trend Micro. (2017, July). Operation Wilted Tulip: Exposing a cyber espionage apparatus. Retrieved August 21, 2017.
  14. Minerva Labs LTD and ClearSky Cyber Security. (2015, November 23). CopyKittens Attack Group. Retrieved September 11, 2017.
  15. Wilhoit, K. and Falcone, R. (2018, September 12). OilRig Uses Updated BONDUPDATER to Target Middle Eastern Government. Retrieved February 18, 2019.
  16. M.Léveillé, M.. (2014, February 21). An In-depth Analysis of Linux/Ebury. Retrieved April 19, 2019.
  17. Falcone, R. and Lee, B.. (2016, May 26). The OilRig Campaign: Attacks on Saudi Arabian Organizations Deliver Helminth Backdoor. Retrieved May 3, 2017.
  18. Dell SecureWorks Counter Threat Unit Threat Intelligence. (2015, August 5). Threat Group-3390 Targets Organizations for Cyberespionage. Retrieved August 18, 2018.
  19. Shelmire, A.. (2015, July 6). Evasive Maneuvers. Retrieved January 22, 2016.
  1. Sardiwal, M, et al. (2017, December 7). New Targeted Attack in the Middle East by APT34, a Suspected Iranian Threat Group, Using CVE-2017-11882 Exploit. Retrieved December 20, 2017.
  2. Davis, S. and Caban, D. (2017, December 19). APT34 - New Targeted Attack in the Middle East. Retrieved December 20, 2017.
  3. Lee, B., Falcone, R. (2018, July 25). OilRig Targets Technology Service Provider and Government Agency with QUADAGENT. Retrieved August 9, 2018.
  4. Symantec Security Response. (2016, August 8). Backdoor.Remsec indicators of compromise. Retrieved August 17, 2016.
  5. Kaspersky Lab's Global Research & Analysis Team. (2016, August 9). The ProjectSauron APT. Retrieved August 17, 2016.
  6. Kaspersky Lab's Global Research & Analysis Team. (2016, August 9). The ProjectSauron APT. Technical Analysis. Retrieved August 17, 2016.
  7. Carr, N., et al. (2018, August 01). On the Hunt for FIN7: Pursuing an Enigmatic and Evasive Global Criminal Operation. Retrieved August 23, 2018.
  8. Fraser, N., et al. (2019, August 7). Double DragonAPT41, a dual espionage and cyber crime operation APT41. Retrieved September 23, 2019.
  9. Grunzweig, J., et al. (2016, May 24). New Wekby Attacks Use DNS Requests As Command and Control Mechanism. Retrieved November 15, 2018.
  10. Svajcer, V. (2018, July 31). Multiple Cobalt Personality Disorder. Retrieved September 5, 2018.
  11. Positive Technologies. (2016, December 16). Cobalt Snatch. Retrieved October 9, 2018.
  12. Matveeva, V. (2017, August 15). Secrets of Cobalt. Retrieved October 10, 2018.
  13. Smallridge, R. (2018, March 10). APT15 is alive and strong: An analysis of RoyalCli and RoyalDNS. Retrieved April 4, 2018.
  14. Unit 42. (2017, December 15). Unit 42 Playbook Viewer. Retrieved December 20, 2017.
  15. Bromiley, M., et al.. (2019, July 18). Hard Pass: Declining APT34’s Invite to Join Their Professional Network. Retrieved August 26, 2019.
  16. Chen, J.. (2020, May 12). Tropic Trooper’s Back: USBferry Attack Targets Air gapped Environments. Retrieved May 20, 2020.
  17. Rusu, B. (2020, May 21). Iranian Chafer APT Targeted Air Transportation and Government in Kuwait and Saudi Arabia. Retrieved May 22, 2020.
  18. Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016.