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 can also be used externally.

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.[2][3]

ID: T1133
Sub-techniques:  No sub-techniques
Platforms: Containers, Linux, Windows
Permissions Required: User
Data Sources: Application Log: Application Log Content, Logon Session: Logon Session Metadata, Network Traffic: Network Traffic Flow
CAPEC ID: CAPEC-555
Contributors: Alfredo Oliveira, Trend Micro; Ariel Shuper, Cisco; Brad Geesaman, @bradgeesaman; Daniel Oakley; David Fiser, @anu4is, Trend Micro; ExtraHop; Idan Frimark, Cisco; Jay Chen, Palo Alto Networks; Magno Logan, @magnologan, Trend Micro; Rory McCune, Aqua Security; Travis Smith, Tripwire; Vishwas Manral, McAfee; Yossi Weizman, Azure Defender Research Team; Yuval Avrahami, Palo Alto Networks
Version: 2.2
Created: 31 May 2017
Last Modified: 22 April 2021

Procedure Examples

ID Name Description
G0026 APT18

APT18 actors leverage legitimate credentials to log into external remote services.[4]

G0016 APT29

APT29 has used compromised identities to access VPNs and remote access tools.[5]

G0096 APT41

APT41 compromised an online billing/payment service using VPN access between a third-party service provider and the targeted payment service.[6]

G0114 Chimera

Chimera has used legitimate credentials to login to an external VPN, Citrix, SSH, and other remote services.[7][8]

S0600 Doki

Doki was executed through an open Docker daemon API port.[9]

G0074 Dragonfly 2.0

Dragonfly 2.0 used VPNs and Outlook Web Access (OWA) to maintain access to victim networks.[10][11]

G0053 FIN5

FIN5 has used legitimate VPN, Citrix, or VNC credentials to maintain access to a victim environment.[12][13][14]

G0093 GALLIUM

GALLIUM has used VPN services, including SoftEther VPN, to access and maintain persistence in victim environments.[15][16]

G0115 GOLD SOUTHFIELD

GOLD SOUTHFIELD has used publicly-accessible RDP and remote management and monitoring (RMM) servers to gain access to victim machines.[17]

S0601 Hildegard

Hildegard was executed through an unsecure kubelet that allowed anonymous access to the victim environment.[3]

G0004 Ke3chang

Ke3chang regained access after eviction via the corporate VPN solution with a stolen VPN certificate, which they had extracted from a compromised host.[18]

G0094 Kimsuky

Kimsuky has used RDP to establish persistence.[19]

S0599 Kinsing

Kinsing was executed in an Ubuntu container deployed via an open Docker daemon API.[20]

S0362 Linux Rabbit

Linux Rabbit attempts to gain access to the server via SSH.[21]

G0014 Night Dragon

Night Dragon has used compromised VPN accounts to gain access to victim systems.[22]

G0049 OilRig

OilRig uses remote services such as VPN, Citrix, or OWA to persist in an environment.[23]

G0116 Operation Wocao

Operation Wocao has used stolen credentials to connect to the victim's network via VPN.[24]

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.[25][26][27]

G0088 TEMP.Veles

TEMP.Veles has used a VPN to persist in the victim environment.[28]

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.[29] 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.[30]

G0102 Wizard Spider

Wizard Spider has accessed victim networks by using stolen credentials to access the corporate VPN infrastructure.[31]

Mitigations

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 Two-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.

Detection

Follow best practices for detecting adversary use of Valid Accounts for authenticating to remote services. Collect authentication logs and analyze for unusual access patterns, windows of activity, and access outside of normal business hours.

When authentication is not required to access an exposed remote service, monitor for follow-on activities such as anomalous external use of the exposed API or application.

References

  1. Adair, S. (2015, October 7). Virtual Private Keylogging: Cisco Web VPNs Leveraged for Access and Persistence. Retrieved March 20, 2017.
  2. Remillano II, A., et al. (2020, June 20). XORDDoS, Kaiji Variants Target Exposed Docker Servers. Retrieved April 5, 2021.
  3. Chen, J. et al. (2021, February 3). Hildegard: New TeamTNT Cryptojacking Malware Targeting Kubernetes. Retrieved April 5, 2021.
  4. Adair, S. (2017, February 17). Detecting and Responding to Advanced Threats within Exchange Environments. Retrieved March 20, 2017.
  5. Nafisi, R., Lelli, A. (2021, March 4). GoldMax, GoldFinder, and Sibot: Analyzing NOBELIUM’s layered persistence. Retrieved March 8, 2021.
  6. Fraser, N., et al. (2019, August 7). Double DragonAPT41, a dual espionage and cyber crime operation APT41. Retrieved September 23, 2019.
  7. Cycraft. (2020, April 15). APT Group Chimera - APT Operation Skeleton key Targets Taiwan Semiconductor Vendors. Retrieved August 24, 2020.
  8. Jansen, W . (2021, January 12). Abusing cloud services to fly under the radar. Retrieved January 19, 2021.
  9. Fishbein, N., Kajiloti, M.. (2020, July 28). Watch Your Containers: Doki Infecting Docker Servers in the Cloud. Retrieved March 30, 2021.
  10. US-CERT. (2018, March 16). Alert (TA18-074A): Russian Government Cyber Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved June 6, 2018.
  11. US-CERT. (2017, October 20). Alert (TA17-293A): Advanced Persistent Threat Activity Targeting Energy and Other Critical Infrastructure Sectors. Retrieved November 2, 2017.
  12. Scavella, T. and Rifki, A. (2017, July 20). Are you Ready to Respond? (Webinar). Retrieved October 4, 2017.
  13. Higgins, K. (2015, October 13). Prolific Cybercrime Gang Favors Legit Login Credentials. Retrieved October 4, 2017.
  14. 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.
  15. Cybereason Nocturnus. (2019, June 25). Operation Soft Cell: A Worldwide Campaign Against Telecommunications Providers. Retrieved July 18, 2019.
  16. MSTIC. (2019, December 12). GALLIUM: Targeting global telecom. Retrieved January 13, 2021.
  1. Counter Threat Unit Research Team. (2019, September 24). REvil/Sodinokibi Ransomware. Retrieved August 4, 2020.
  2. Smallridge, R. (2018, March 10). APT15 is alive and strong: An analysis of RoyalCli and RoyalDNS. Retrieved April 4, 2018.
  3. CISA, FBI, CNMF. (2020, October 27). https://us-cert.cisa.gov/ncas/alerts/aa20-301a. Retrieved November 4, 2020.
  4. Singer, G. (2020, April 3). Threat Alert: Kinsing Malware Attacks Targeting Container Environments. Retrieved April 1, 2021.
  5. Anomali Labs. (2018, December 6). Pulling Linux Rabbit/Rabbot Malware Out of a Hat. Retrieved March 4, 2019.
  6. McAfee® Foundstone® Professional Services and McAfee Labs™. (2011, February 10). Global Energy Cyberattacks: “Night Dragon”. Retrieved February 19, 2018.
  7. Davis, S. and Caban, D. (2017, December 19). APT34 - New Targeted Attack in the Middle East. Retrieved December 20, 2017.
  8. 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.
  9. Cherepanov, A.. (2016, January 3). BlackEnergy by the SSHBearDoor: attacks against Ukrainian news media and electric industry . Retrieved June 10, 2020.
  10. Cherepanov, A.. (2017, June 30). TeleBots are back: Supply chain attacks against Ukraine. Retrieved June 11, 2020.
  11. ANSSI. (2021, January 27). SANDWORM INTRUSION SET CAMPAIGN TARGETING CENTREON SYSTEMS. Retrieved March 30, 2021.
  12. Miller, S, et al. (2019, April 10). TRITON Actor TTP Profile, Custom Attack Tools, Detections, and ATT&CK Mapping. Retrieved April 16, 2019.
  13. Dell SecureWorks Counter Threat Unit Threat Intelligence. (2015, August 5). Threat Group-3390 Targets Organizations for Cyberespionage. Retrieved August 18, 2018.
  14. Counter Threat Unit Research Team. (2017, June 27). BRONZE UNION Cyberespionage Persists Despite Disclosures. Retrieved July 13, 2017.
  15. 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.