Skip to content

T1001.003 Protocol Impersonation

Adversaries may impersonate legitimate protocols or web service traffic to disguise command and control activity and thwart analysis efforts. By impersonating legitimate protocols or web services, adversaries can make their command and control traffic blend in with legitimate network traffic.

Adversaries may impersonate a fake SSL/TLS handshake to make it look like subsequent traffic is SSL/TLS encrypted, potentially interfering with some security tooling, or to make the traffic look like it is related with a trusted entity.

Item Value
ID T1001.003
Sub-techniques T1001.001, T1001.002, T1001.003
Tactics TA0011
Platforms Linux, Windows, macOS
Version 1.0
Created 15 March 2020
Last Modified 15 March 2020

Procedure Examples

ID Name Description
S0245 BADCALL BADCALL uses a FakeTLS method during C2.9
S0239 Bankshot Bankshot generates a false TLS handshake using a public certificate to disguise C2 network communications.4
C0017 C0017 During C0017, APT41 frequently configured the URL endpoints of their stealthy passive backdoor LOWKEY.PASSIVE to masquerade as normal web application traffic on an infected server.19
S0154 Cobalt Strike Cobalt Strike can mimic the HTTP protocol for C2 communication, while hiding the actual data in either an HTTP header, URI parameter, the transaction body, or appending it to the URI.3
S0076 FakeM FakeM C2 traffic attempts to evade detection by resembling data generated by legitimate messenger applications, such as MSN and Yahoo! messengers. Additionally, some variants of FakeM use modified SSL code for communications back to C2 servers, making SSL decryption ineffective.5
S0181 FALLCHILL FALLCHILL uses fake Transport Layer Security (TLS) to communicate with its C2 server.2
S0246 HARDRAIN HARDRAIN uses FakeTLS to communicate with its C2 server.10
G0126 Higaisa Higaisa used a FakeTLS session for C2 communications.18
S0260 InvisiMole InvisiMole can mimic HTTP protocol with custom HTTP “verbs” HIDE, ZVVP, and NOP.67
S0387 KeyBoy KeyBoy uses custom SSL libraries to impersonate SSL in C2 traffic.8
G0032 Lazarus Group Lazarus Group malware also uses a unique form of communication encryption known as FakeTLS that mimics TLS but uses a different encryption method, potentially evading SSL traffic inspection/decryption.15141617
S0439 Okrum Okrum mimics HTTP protocol for C2 communication, while hiding the actual messages in the Cookie and Set-Cookie headers of the HTTP requests.12
S0559 SUNBURST SUNBURST masqueraded its network traffic as the Orion Improvement Program (OIP) protocol.11
S0586 TAINTEDSCRIBE TAINTEDSCRIBE has used FakeTLS for session authentication.13


ID Mitigation Description
M1031 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 some obfuscation activity at the network level.


ID Data Source Data Component
DS0029 Network Traffic Network Traffic Content


  1. Gardiner, J., Cova, M., Nagaraja, S. (2014, February). Command & Control Understanding, Denying and Detecting. Retrieved April 20, 2016. 

  2. US-CERT. (2017, November 22). Alert (TA17-318A): HIDDEN COBRA – North Korean Remote Administration Tool: FALLCHILL. Retrieved December 7, 2017. 

  3. Strategic Cyber LLC. (2020, November 5). Cobalt Strike: Advanced Threat Tactics for Penetration Testers. Retrieved April 13, 2021. 

  4. US-CERT. (2017, December 13). Malware Analysis Report (MAR) - 10135536-B. Retrieved July 17, 2018. 

  5. Falcone, R. and Miller-Osborn, J.. (2016, January 24). Scarlet Mimic: Years-Long Espionage Campaign Targets Minority Activists. Retrieved February 10, 2016. 

  6. Hromcová, Z. (2018, June 07). InvisiMole: Surprisingly equipped spyware, undercover since 2013. Retrieved July 10, 2018. 

  7. Hromcova, Z. and Cherpanov, A. (2020, June). INVISIMOLE: THE HIDDEN PART OF THE STORY. Retrieved July 16, 2020. 

  8. Parys, B. (2017, February 11). The KeyBoys are back in town. Retrieved June 13, 2019. 

  9. US-CERT. (2018, February 06). Malware Analysis Report (MAR) - 10135536-G. Retrieved June 7, 2018. 

  10. US-CERT. (2018, February 05). Malware Analysis Report (MAR) - 10135536-F. Retrieved June 11, 2018. 

  11. FireEye. (2020, December 13). Highly Evasive Attacker Leverages SolarWinds Supply Chain to Compromise Multiple Global Victims With SUNBURST Backdoor. Retrieved January 4, 2021. 

  12. Hromcova, Z. (2019, July). OKRUM AND KETRICAN: AN OVERVIEW OF RECENT KE3CHANG GROUP ACTIVITY. Retrieved May 6, 2020. 

  13. USG. (2020, May 12). MAR-10288834-2.v1 – North Korean Trojan: TAINTEDSCRIBE. Retrieved March 5, 2021. 

  14. Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Destructive Malware Report. Retrieved March 2, 2016. 

  15. Novetta Threat Research Group. (2016, February 24). Operation Blockbuster: Unraveling the Long Thread of the Sony Attack. Retrieved February 25, 2016. 

  16. Sherstobitoff, R. (2018, February 12). Lazarus Resurfaces, Targets Global Banks and Bitcoin Users. Retrieved February 19, 2018. 

  17. Sherstobitoff, R., Malhotra, A. (2018, April 24). Analyzing Operation GhostSecret: Attack Seeks to Steal Data Worldwide. Retrieved May 16, 2018. 

  18. Singh, S. Singh, A. (2020, June 11). The Return on the Higaisa APT. Retrieved March 2, 2021. 

  19. Rufus Brown, Van Ta, Douglas Bienstock, Geoff Ackerman, John Wolfram. (2022, March 8). Does This Look Infected? A Summary of APT41 Targeting U.S. State Governments. Retrieved July 8, 2022.