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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.(Citation: MacOS VNC software for Remote Desktop)

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.(Citation: Volexity Virtual Private Keylogging) 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.(Citation: Trend Micro Exposed Docker Server)(Citation: Unit 42 Hildegard Malware)

View in MITRE ATT&CK®

CRI Profile Mappings

Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
PR.IR-01.05 Remote access protection Mitigates T1133 External Remote Services
Comments
This diagnostic statement implements security controls and restrictions for remote user access to systems. Remote user access control involves managing and securing how users remotely access systems, such as through encrypted connections and account use policies, which help prevent adversary access.
References
    PR.IR-01.06 Production environment segregation Mitigates T1133 External Remote Services
    Comments
    This diagnostic statement provides protections for production environments. Measures such as network segmentation and access control reduce the attack surface, restrict movement by adversaries, and protect critical assets and data from compromise.
    References
      PR.AA-05.02 Privileged system access Mitigates T1133 External Remote Services
      Comments
      This diagnostic statement protects against External Remote Services through the use of privileged account management and the use of multi-factor authentication.
      References
        PR.AA-05.01 Access privilege limitation Mitigates T1133 External Remote Services
        Comments
        This diagnostic statement describes the implementation of least privilege principle, which can be applied to limiting permissions through role-based access controls, file and directory permissions, and the execution of systems and services. Limiting users' access to resources over network can help mitigate these techniques. Limit access to remote services through centrally managed concentrators such as VPNs and other managed remote access systems.
        References
          PR.PS-01.07 Cryptographic keys and certificates Mitigates T1133 External Remote Services
          Comments
          This diagnostic statement protects against External Remote Services through the use of revocation of keys and key management. Employing key protection strategies and key management for those used in external remote services, limitations to specific accounts along with access control mechanisms provides protection against adversaries attempting to access external remote services.
          References
            PR.AA-03.01 Authentication requirements Mitigates T1133 External Remote Services
            Comments
            This diagnostic statement describes how the organization implement appropriate authentication requirements, including selecting mechanisms based on risk, utilizing multi-factor authentication where necessary, and safeguarding the storage of authenticators like pins and passwords to protect sensitive access credentials.
            References
              PR.IR-01.01 Network segmentation Mitigates T1133 External Remote Services
              Comments
              This diagnostic statement is for the implementation of network segmentation which helps prevent access to critical systems and sensitive information. Denying direct remote access to internal systems to prevent adversaries from leveraging external-facing remote services to access and/or persist within a network.
              References
                PR.IR-04.01 Utilization monitoring Mitigates T1133 External Remote Services
                Comments
                This diagnostic statement describes how the organization establishes and manages baseline measures of network activity. Supported by network monitoring tools and other controls to detect events and identify incidents. Mitigating mechanisms may include: Data Loss Prevention (DLP); Filtering Network Traffic; Limit Network Traffic; Network Intrusion Prevention Systems (NIPS); and Network Segmentation for these type of network-based techniques.
                References
                  PR.IR-01.02 Network device configurations Mitigates T1133 External Remote Services
                  Comments
                  This diagnostic statement provides protection through secure network device configurations (e.g., firewall rules, ports, protocols) aligned to security baselines. Using network appliances to block or filter network traffic that is not necessary within the environment can mitigate adversaries from leveraging externally-facing remote services to initially access and/or persist within a network.
                  References
                    PR.IR-01.03 Network communications integrity and availability Mitigates T1133 External Remote Services
                    Comments
                    This diagnostic statement protects against External Remote Services through the use of secure network configurations, architecture, implementations of zero trust architecture, and segmentation.
                    References
                      PR.AA-01.01 Identity and credential management Mitigates T1133 External Remote Services
                      Comments
                      This diagnostic statement protects against External Remote Services through the use of hardened access control policies, secure defaults, password complexity requirements, multifactor authentication requirements, and removal of terminated accounts.
                      References
                        PR.PS-01.08 End-user device protection Mitigates T1133 External Remote Services
                        Comments
                        This diagnostic statement protects against External Remote Services through the use of limiting access to resources to only authorized devices, management of personal computing devices, network intrusion prevention, and the use of antimalware.
                        References

                          NIST 800-53 Mappings

                          Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
                          CM-06 Configuration Settings mitigates T1133 External Remote Services
                          IA-05 Authenticator Management mitigates T1133 External Remote Services
                          AC-17 Remote Access mitigates T1133 External Remote Services
                          RA-05 Vulnerability Monitoring and Scanning mitigates T1133 External Remote Services
                          CM-08 System Component Inventory mitigates T1133 External Remote Services
                          SC-46 Cross Domain Policy Enforcement mitigates T1133 External Remote Services
                          SI-07 Software, Firmware, and Information Integrity mitigates T1133 External Remote Services
                          AC-20 Use of External Systems mitigates T1133 External Remote Services
                          CM-02 Baseline Configuration mitigates T1133 External Remote Services
                          IA-02 Identification and Authentication (Organizational Users) mitigates T1133 External Remote Services
                          CM-07 Least Functionality mitigates T1133 External Remote Services
                          SI-04 System Monitoring mitigates T1133 External Remote Services
                          AC-03 Access Enforcement mitigates T1133 External Remote Services
                          AC-04 Information Flow Enforcement mitigates T1133 External Remote Services
                          AC-06 Least Privilege mitigates T1133 External Remote Services
                          AC-07 Unsuccessful Logon Attempts mitigates T1133 External Remote Services
                          SC-07 Boundary Protection mitigates T1133 External Remote Services

                          VERIS Mappings

                          Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
                          action.hacking.variety.Backdoor Hacking action that creates a backdoor for use. related-to T1133 External Remote Services
                          action.hacking.variety.Use of stolen creds Use of stolen or default authentication credentials (including credential stuffing) related-to T1133 External Remote Services
                          action.hacking.vector.3rd party desktop 3rd party online desktop sharing (LogMeIn, Go2Assist) related-to T1133 External Remote Services
                          action.hacking.vector.Backdoor Hacking actions taken through a backdoor. C2 is only used by malware. related-to T1133 External Remote Services
                          action.hacking.vector.Desktop sharing software Superset of 'Desktop sharing' and '3rd party desktop'. Please use in place of the other two related-to T1133 External Remote Services
                          action.hacking.vector.VPN VPN related-to T1133 External Remote Services
                          action.malware.variety.Backdoor Malware creates a backdoor capability for hacking. Child of 'RAT' when combined with 'Trojan'. Child of 'Backdoor or C2'. related-to T1133 External Remote Services
                          action.malware.vector.Remote injection Remotely injected by agent (i.e. via SQLi) related-to T1133 External Remote Services
                          action.malware.vector.Web application Web application. Parent of 'Web application - download' and 'Web application - drive-by. related-to T1133 External Remote Services

                          Azure Mappings

                          Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
                          ai_security_recommendations Microsoft Defender for Cloud: AI Security Recommendations technique_scores T1133 External Remote Services
                          Comments
                          This control's "Management ports should be closed on your virtual machines" recommendation can lead to reducing the attack surface of your Azure VMs by recommending closing management ports. Because this is a recommendation, its score is limited to Partial.
                          References
                          1. https://learn.microsoft.com/en-us/azure/defender-for-cloud/recommendations-reference-ai
                          alerts_for_azure_network_layer Alerts for Azure Network Layer technique_scores T1133 External Remote Services
                          Comments
                          This control can potentially identify malicious use of remote services via alerts such as "Suspicious incoming RDP network activity" and "Suspicious Incoming SSH network activity".
                          References
                          1. https://learn.microsoft.com/en-us/azure/defender-for-cloud/alerts-reference#alerts-azurenetlayer
                          azure_firewall Azure Firewall technique_scores T1133 External Remote Services
                          Comments
                          This control can limit access to external remote services to the minimum necessary.
                          References
                          1. https://learn.microsoft.com/en-us/azure/firewall/overview
                          azure_network_security_groups Azure Network Security Groups technique_scores T1133 External Remote Services
                          Comments
                          This control can be used to restrict direct access to remote service gateways and concentrators that typically accompany external remote services. This can be circumvented though if an adversary is able to compromise a trusted host and use it to access the external remote service. This results in an overall partial (coverage) score.
                          References
                          1. https://learn.microsoft.com/en-us/azure/virtual-network/network-security-groups-overview
                          2. https://learn.microsoft.com/en-us/azure/virtual-network/network-security-group-how-it-works
                          3. https://learn.microsoft.com/en-us/azure/defender-for-cloud/prepare-deprecation-log-analytics-mma-agent#feature-functionality
                          azure_network_watcher_traffic_analytics Azure Network Watcher: Traffic Analytics technique_scores T1133 External Remote Services
                          Comments
                          This control can identify anomalous access to external remote services.
                          References
                          1. https://learn.microsoft.com/en-us/azure/network-watcher/traffic-analytics
                          azure_policy Azure Policy technique_scores T1133 External Remote Services
                          Comments
                          This control may provide recommendations to secure external remote services, such as restricting SSH access, enabling multi-factor authentication for VPN access, and auditing external remote services that are not necessary or updated.
                          References
                          1. https://learn.microsoft.com/en-us/azure/governance/policy/overview
                          2. https://learn.microsoft.com/en-us/azure/governance/policy/samples/built-in-policies#api-for-fhir
                          just-in-time_vm_access Microsoft Defender for Cloud: Just-in-Time VM Access technique_scores T1133 External Remote Services
                          Comments
                          This control can be configured to completely block inbound access to selected ports until access is requested. This prevents any attempt at utilizing external remote services, such as RDP or a VPN, unless the attacker has the credentials and permissions to request such access. Even if permission has been granted to an authorized user to access the virtual machine, a list of authorized IP addresses for that access can be configured.
                          References
                          1. https://learn.microsoft.com/en-us/azure/defender-for-cloud/just-in-time-access-usage?tabs=jit-config-asc%2Cjit-request-api
                          2. https://learn.microsoft.com/en-us/azure/defender-for-cloud/just-in-time-access-overview

                          GCP Mappings

                          Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
                          mandiant_asm Mandiant Attack Surface Management (ASM) technique_scores T1133 External Remote Services
                          Comments
                          Mandiant Attack Surface Management continuously discovers and assesses an organization's assets for vulnerabilities, misconfigurations, and exposures. This control can discover vulnerable Remote Services offered on the cloud or on hosted servers. Since this monitoring is continual and is derived from Mandiant cyber threat intelligence, this control is scored as significant.
                          References
                          1. ['https://cloud.google.com/security/products/attack-surface-management']
                          advanced_protection_program Advanced Protection Program technique_scores T1133 External Remote Services
                          Comments
                          Advanced Protection Program enables the use of a security key for multi-factor authentication. Enabling MFA for remote service accounts can mitigate an adversary's ability to leverage stolen credentials since they won't have the respective security key to gain access.
                          References
                          1. ['https://landing.google.com/advancedprotection/']
                          chrome_enterprise_premium Chrome Enterprise Premium technique_scores T1133 External Remote Services
                          Comments
                          Chrome Enterprise Premium implements a zero trust model which restricts access to resources unless all rules and conditions are met. Instead of securing resources at the network-level, access controls are instead applied to individual devices and users.
                          References
                          1. ['https://cloud.google.com/beyondcorp-enterprise/docs/overview']
                          cloud_identity Cloud Identity technique_scores T1133 External Remote Services
                          Comments
                          This control may mitigate an adversary's ability to leverage external-facing remote services through multi-factor authentication of service account credentials.
                          References
                          1. ['https://cloud.google.com/identity']
                          cloud_ngfw Cloud Next-Generation Firewall (NGFW)_ technique_scores T1133 External Remote Services
                          Comments
                          Cloud NGFW can allow or deny traffic based on the traffic's protocol, destination ports, sources, and destinations. This functionality can be used to only allow certain remote services to be available. Furthermore, it can enforce restrictions such that remote services are only from trusted hosts (i.e., only allow remote access traffic from certain hosts). This mapping is given a score of Partial because while it can limit which external remote services and hosts can be used to access the network, it cannot protect against the misuse of legitimate external remote services (e.g., it cannot protect against an adversary using a trusted host that is permitted to use remote services as part of an attack).
                          References
                          1. ['https://cloud.google.com/firewalls']
                          cloud_vpn Cloud VPN technique_scores T1133 External Remote Services
                          Comments
                          This control provides protections against adversaries who try to 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.
                          References
                          1. ['https://cloud.google.com/network-connectivity/docs/vpn/concepts/overview']
                          security_command_center Security Command Center technique_scores T1133 External Remote Services
                          Comments
                          SCC is able to detect attackers communicating with a compromised workload from a remote system (e.g., "reverse shell"). SCC specifically detects for stdin bound to a remote socket. Because of the high threat detection coverage and near-real time temporal factor this control was graded as significant.
                          References
                          1. ['https://cloud.google.com/security-command-center/docs/concepts-security-command-center-overview'
                          2. 'https://github.com/GoogleCloudPlatform/security-analytics']

                          AWS Mappings

                          Capability ID Capability Description Mapping Type ATT&CK ID ATT&CK Name Notes
                          amazon_inspector Amazon Inspector technique_scores T1133 External Remote Services
                          Comments
                          The Amazon Inspector Best Practices assessment package can detect a security control setting related to remote service access on Linux endpoints. Specifically, "Disable root login over SSH". This information can be used identify insecure configurations and harden the endpoints. Amazon Inspector does not directly protect against adversaries accessing remote services. Given Amazon Inspector can only assess this security control on Linux platforms (although it also supports Windows) and it only restricts access to remote services for one user account, the coverage score is Minimal leading to an overall Minimal score.
                          References
                          1. https://docs.aws.amazon.com/inspector/latest/userguide/inspector_introduction.html
                          amazon_virtual_private_cloud Amazon Virtual Private Cloud technique_scores T1133 External Remote Services
                          Comments
                          VPC security groups and network access control lists (NACLs) can limit access to external remote services to the minimum necessary.
                          References
                          1. https://docs.aws.amazon.com/vpc/latest/userguide/security.html
                          aws_network_firewall AWS Network Firewall technique_scores T1133 External Remote Services
                          Comments
                          AWS Network Firewall has the ability to pass, drop, or alert on traffic based on the network protocol as well as perform deep packet inspection on the payload. This functionality can be used to only allow certain remote services to be available. Futhermore, it can enforce restrictions such that remote services are only from trusted hosts (i.e., only allow remote access traffic from certain hosts). This mapping is given a score of Partial because while it can limit which external remote services and hosts can be used to access the network, it cannot protect against the misuse of legitimate external remote services (e.g., it cannot protect against an adversary using a trusted host that is permitted to use remote services as part of an attack).
                          References
                          1. https://docs.aws.amazon.com/network-firewall/latest/developerguide/what-is-aws-network-firewall.html
                          aws_single_sign-on AWS Single Sign-On technique_scores T1133 External Remote Services
                          Comments
                          This control may protect against abuse of external remote services by requiring multi-factor authentication for single sign-on accounts.
                          References
                          1. https://docs.aws.amazon.com/singlesignon/latest/userguide/what-is.html