Skip to content

T1133 External Remote Services

Adversaries may leverage external-facing remote services to initially access and/or persist within a network. Remote services such as VPNs, Citrix, and other access mechanisms allow users to connect to internal enterprise network resources from external locations. There are often remote service gateways that manage connections and credential authentication for these services. Services such as Windows Remote Management and VNC can also be used externally.2

Access to Valid Accounts to use the service is often a requirement, which could be obtained through credential pharming or by obtaining the credentials from users after compromising the enterprise network.1 Access to remote services may be used as a redundant or persistent access mechanism during an operation.

Access may also be gained through an exposed service that doesn’t require authentication. In containerized environments, this may include an exposed Docker API, Kubernetes API server, kubelet, or web application such as the Kubernetes dashboard.43

Item Value
ID T1133
Tactics TA0003, TA0001
Platforms Containers, Linux, Windows, macOS
Version 2.4
Created 31 May 2017
Last Modified 30 March 2023

Procedure Examples

ID Name Description
G0026 APT18 APT18 actors leverage legitimate credentials to log into external remote services.16
G0007 APT28 APT28 has used Tor and a variety of commercial VPN services to route brute force authentication attempts.28
G0016 APT29 APT29 has used compromised identities to access networks via VPNs and Citrix.1817
G0096 APT41 APT41 compromised an online billing/payment service using VPN access between a third-party service provider and the targeted payment service.22
G0114 Chimera Chimera has used legitimate credentials to login to an external VPN, Citrix, SSH, and other remote services.2526
C0004 CostaRicto During CostaRicto, the threat actors set up remote tunneling using an SSH tool to maintain access to a compromised environment.42
S0600 Doki Doki was executed through an open Docker daemon API port.8
G0035 Dragonfly Dragonfly has used VPNs and Outlook Web Access (OWA) to maintain access to victim networks.910
G0053 FIN5 FIN5 has used legitimate VPN, Citrix, or VNC credentials to maintain access to a victim environment.131415
G0093 GALLIUM GALLIUM has used VPN services, including SoftEther VPN, to access and maintain persistence in victim environments.3132
G0115 GOLD SOUTHFIELD GOLD SOUTHFIELD has used publicly-accessible RDP and remote management and monitoring (RMM) servers to gain access to victim machines.29
S0601 Hildegard Hildegard was executed through an unsecure kubelet that allowed anonymous access to the victim environment.3
G0004 Ke3chang Ke3chang has gained access through VPNs including with compromised accounts and stolen VPN certificates.3738
G0094 Kimsuky Kimsuky has used RDP to establish persistence.30
S0599 Kinsing Kinsing was executed in an Ubuntu container deployed via an open Docker daemon API.7
G1004 LAPSUS$ LAPSUS$ has gained access to internet-facing systems and applications, including virtual private network (VPN), remote desktop protocol (RDP), and virtual desktop infrastructure (VDI) including Citrix. 12
G0065 Leviathan Leviathan has used external remote services such as virtual private networks (VPN) to gain initial access.33
S0362 Linux Rabbit Linux Rabbit attempts to gain access to the server via SSH.6
S1060 Mafalda Mafalda can establish an SSH connection from a compromised host to a server.5
C0002 Night Dragon During Night Dragon, threat actors used compromised VPN accounts to gain access to victim systems.43
G0049 OilRig OilRig uses remote services such as VPN, Citrix, or OWA to persist in an environment.11
C0012 Operation CuckooBees During Operation CuckooBees, the threat actors enabled WinRM over HTTP/HTTPS as a backup persistence mechanism using the following command: cscript //nologo "C:\Windows\System32\winrm.vbs" set winrm/config/service@{EnableCompatibilityHttpsListener="true"}.39
C0014 Operation Wocao During Operation Wocao, threat actors used stolen credentials to connect to the victim’s network via VPN.44
G0034 Sandworm Team Sandworm Team has used Dropbear SSH with a hardcoded backdoor password to maintain persistence within the target network. Sandworm Team has also used VPN tunnels established in legitimate software company infrastructure to gain access to internal networks of that software company’s users.192021
C0024 SolarWinds Compromise For the SolarWinds Compromise, APT29 used compromised identities to access networks via SSH, VPNs, and other remote access tools.4140
G0139 TeamTNT TeamTNT has used open-source tools such as Weave Scope to target exposed Docker API ports and gain initial access to victim environments.3635 TeamTNT has also targeted exposed kubelets for Kubernetes environments.3
G0088 TEMP.Veles TEMP.Veles has used a VPN to persist in the victim environment.34
G0027 Threat Group-3390 Threat Group-3390 actors look for and use VPN profiles during an operation to access the network using external VPN services.23 Threat Group-3390 has also obtained OWA account credentials during intrusions that it subsequently used to attempt to regain access when evicted from a victim network.24
G0102 Wizard Spider Wizard Spider has accessed victim networks by using stolen credentials to access the corporate VPN infrastructure.27


ID Mitigation Description
M1042 Disable or Remove Feature or Program Disable or block remotely available services that may be unnecessary.
M1035 Limit Access to Resource Over Network Limit access to remote services through centrally managed concentrators such as VPNs and other managed remote access systems.
M1032 Multi-factor Authentication Use strong two-factor or multi-factor authentication for remote service accounts to mitigate an adversary’s ability to leverage stolen credentials, but be aware of Multi-Factor Authentication Interception techniques for some two-factor authentication implementations.
M1030 Network Segmentation Deny direct remote access to internal systems through the use of network proxies, gateways, and firewalls.


ID Data Source Data Component
DS0015 Application Log Application Log Content
DS0028 Logon Session Logon Session Metadata
DS0029 Network Traffic Network Connection Creation


  1. Adair, S. (2015, October 7). Virtual Private Keylogging: Cisco Web VPNs Leveraged for Access and Persistence. Retrieved March 20, 2017. 

  2. Apple Support. (n.d.). Set up a computer running VNC software for Remote Desktop. Retrieved August 18, 2021. 

  3. Chen, J. et al. (2021, February 3). Hildegard: New TeamTNT Cryptojacking Malware Targeting Kubernetes. Retrieved April 5, 2021. 

  4. Remillano II, A., et al. (2020, June 20). XORDDoS, Kaiji Variants Target Exposed Docker Servers. Retrieved April 5, 2021. 

  5. SentinelLabs. (2022, September 22). Metador Technical Appendix. Retrieved April 4, 2023. 

  6. Anomali Labs. (2018, December 6). Pulling Linux Rabbit/Rabbot Malware Out of a Hat. Retrieved March 4, 2019. 

  7. Singer, G. (2020, April 3). Threat Alert: Kinsing Malware Attacks Targeting Container Environments. Retrieved April 1, 2021. 

  8. Fishbein, N., Kajiloti, M.. (2020, July 28). Watch Your Containers: Doki Infecting Docker Servers in the Cloud. Retrieved March 30, 2021. 

  9. US-CERT. (2018, March 16). Alert (TA18-074A): Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved June 6, 2018. 

  10. CISA. (2020, December 1). Russian State-Sponsored Advanced Persistent Threat Actor Compromises U.S. Government Targets. Retrieved December 9, 2021. 

  11. Davis, S. and Caban, D. (2017, December 19). APT34 - New Targeted Attack in the Middle East. Retrieved December 20, 2017. 

  12. MSTIC, DART, M365 Defender. (2022, March 24). DEV-0537 Criminal Actor Targeting Organizations for Data Exfiltration and Destruction. Retrieved May 17, 2022. 

  13. Scavella, T. and Rifki, A. (2017, July 20). Are you Ready to Respond? (Webinar). Retrieved October 4, 2017. 

  14. Higgins, K. (2015, October 13). Prolific Cybercrime Gang Favors Legit Login Credentials. Retrieved October 4, 2017. 

  15. Bromiley, M. and Lewis, P. (2016, October 7). Attacking the Hospitality and Gaming Industries: Tracking an Attacker Around the World in 7 Years. Retrieved October 6, 2017. 

  16. Adair, S. (2017, February 17). Detecting and Responding to Advanced Threats within Exchange Environments. Retrieved March 20, 2017. 

  17. Douglas Bienstock. (2022, August 18). You Can’t Audit Me: APT29 Continues Targeting Microsoft 365. Retrieved February 23, 2023. 

  18. National Cyber Security Centre. (2020, July 16). Advisory: APT29 targets COVID-19 vaccine development. Retrieved September 29, 2020. 

  19. Cherepanov, A.. (2016, January 3). BlackEnergy by the SSHBearDoor: attacks against Ukrainian news media and electric industry . Retrieved June 10, 2020. 

  20. Cherepanov, A.. (2017, June 30). TeleBots are back: Supply chain attacks against Ukraine. Retrieved June 11, 2020. 


  22. Fraser, N., et al. (2019, August 7). Double DragonAPT41, a dual espionage and cyber crime operation APT41. Retrieved September 23, 2019. 

  23. Dell SecureWorks Counter Threat Unit Threat Intelligence. (2015, August 5). Threat Group-3390 Targets Organizations for Cyberespionage. Retrieved August 18, 2018. 

  24. Counter Threat Unit Research Team. (2017, June 27). BRONZE UNION Cyberespionage Persists Despite Disclosures. Retrieved July 13, 2017. 

  25. Cycraft. (2020, April 15). APT Group Chimera - APT Operation Skeleton key Targets Taiwan Semiconductor Vendors. Retrieved August 24, 2020. 

  26. Jansen, W . (2021, January 12). Abusing cloud services to fly under the radar. Retrieved January 19, 2021. 

  27. Kimberly Goody, Jeremy Kennelly, Joshua Shilko, Steve Elovitz, Douglas Bienstock. (2020, October 28). Unhappy Hour Special: KEGTAP and SINGLEMALT With a Ransomware Chaser. Retrieved October 28, 2020. 

  28. NSA, CISA, FBI, NCSC. (2021, July). Russian GRU Conducting Global Brute Force Campaign to Compromise Enterprise and Cloud Environments. Retrieved July 26, 2021. 

  29. Counter Threat Unit Research Team. (2019, September 24). REvil/Sodinokibi Ransomware. Retrieved August 4, 2020. 

  30. CISA, FBI, CNMF. (2020, October 27). Retrieved November 4, 2020. 

  31. Cybereason Nocturnus. (2019, June 25). Operation Soft Cell: A Worldwide Campaign Against Telecommunications Providers. Retrieved July 18, 2019. 

  32. MSTIC. (2019, December 12). GALLIUM: Targeting global telecom. Retrieved January 13, 2021. 

  33. CISA. (2021, July 19). (AA21-200A) Joint Cybersecurity Advisory – Tactics, Techniques, and Procedures of Indicted APT40 Actors Associated with China’s MSS Hainan State Security Department. Retrieved August 12, 2021. 

  34. Miller, S, et al. (2019, April 10). TRITON Actor TTP Profile, Custom Attack Tools, Detections, and ATT&CK Mapping. Retrieved April 16, 2019. 

  35. Darin Smith. (2022, April 21). TeamTNT targeting AWS, Alibaba. Retrieved August 4, 2022. 

  36. Fishbein, N. (2020, September 8). Attackers Abusing Legitimate Cloud Monitoring Tools to Conduct Cyber Attacks. Retrieved September 22, 2021. 

  37. Smallridge, R. (2018, March 10). APT15 is alive and strong: An analysis of RoyalCli and RoyalDNS. Retrieved April 4, 2018. 

  38. MSTIC. (2021, December 6). NICKEL targeting government organizations across Latin America and Europe. Retrieved March 18, 2022. 

  39. Cybereason Nocturnus. (2022, May 4). Operation CuckooBees: Deep-Dive into Stealthy Winnti Techniques. Retrieved September 22, 2022. 

  40. CrowdStrike. (2022, January 27). Early Bird Catches the Wormhole: Observations from the StellarParticle Campaign. Retrieved February 7, 2022. 

  41. Nafisi, R., Lelli, A. (2021, March 4). GoldMax, GoldFinder, and Sibot: Analyzing NOBELIUM’s layered persistence. Retrieved March 8, 2021. 

  42. The BlackBerry Research and Intelligence Team. (2020, November 12). The CostaRicto Campaign: Cyber-Espionage Outsourced. Retrieved May 24, 2021. 

  43. McAfee® Foundstone® Professional Services and McAfee Labs™. (2011, February 10). Global Energy Cyberattacks: “Night Dragon”. Retrieved February 19, 2018. 

  44. Dantzig, M. v., Schamper, E. (2019, December 19). Operation Wocao: Shining a light on one of China’s hidden hacking groups. Retrieved October 8, 2020.