Query: explain T1133 External Remote Services
Matching passage: T1133 External Remote Services. Tactics: persistence, initial access. Description: 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](https://attack.mitre.org/techniques/T1021/006) and [VNC](https://attack.mitre.org/techniques/T1021/005) can also be used externally.(Citation: MacOS VNC software for Remote Desktop) Access to [Valid Accounts](https://attack.mitre.org/techniques/T1078) 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) Adversaries may also establish persistence on network by configuring a Tor hidden service on a compromised system. Adversaries may utilize the tool `ShadowLink` to facilitate the installation and configuration of the Tor hidden service. Tor hidden service is then accessible via the Tor network because `ShadowLink` sets up a .onion address on the compromised system. `ShadowLink` may be used to forward any inbound connections to RDP, allowing the adversaries to have remote access.(Citation: The BadPilot campaign) Adversaries may get `ShadowLink` to persist on a system by masquerading it as an MS Defender application.(Citation: Russian threat actors dig in,
Near-miss passage: T1543.002 Systemd Service. Tactics: persistence, privilege escalation. Description: Adversaries may create or modify systemd services to repeatedly execute malicious payloads as part of persistence. Systemd is a system and service manager commonly used for managing background daemon processes (also known as services) and other system resources.(Citation: Linux man-pages: systemd January 2014) Systemd is the default initialization (init) system on many Linux distributions replacing legacy init systems, including SysVinit and Upstart, while remaining backwards compatible. Systemd utilizes unit configuration files with the `.service` file extension to encode information about a service's process. By default, system level unit files are stored in the `/systemd/system` directory of the root owned directories (`/`). User level unit files are stored in the `/systemd/user` directories of the user owned directories (`$HOME`).(Citation: lambert systemd 2022) Inside the `.service` unit files, the following directives are used to execute commands:(Citation: freedesktop systemd.service) * `ExecStart`, `ExecStartPre`, and `ExecStartPost` directives execute when a service is started manually by `systemctl` or on system start if the service is set to automatically start. * `ExecReload` directive executes when a service restarts. * `ExecStop`, `ExecStopPre`, and `ExecStopPost` directives execute when a service is stopped. Adversaries have created new service files, altered the commands a `.service` file’s directive executes, and modified the user directive a `.service` file executes as, which could result in privilege escalation. Adversaries may also place symbolic links in these directories, enabling systemd to find these payloads regardless of where they reside on the filesystem.(Citation: Anomali Rocke March 2019)(Citation: airwalk backdoor unix systems)(Citation: Rapid7 Service Persistence 22JUNE2016) The `.service` file’s User directive can be used to run service as a specific user, which could result in privilege escalation based on specific user/group permis