Remote Access Tools

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Remote Access Tools
Technique
ID T1219
Tactic Command and Control
Platform Linux, Windows, macOS
Permissions Required User
Data Sources Network intrusion detection system, Network protocol analysis, Process use of network, Process Monitoring
Requires Network Yes
Contributors Matt Kelly, @breakersall

An adversary may use legitimate desktop support and remote access software, such as Team Viewer, Go2Assist, LogMein, AmmyyAdmin, etc, to establish an interactive command and control channel to target systems within networks. These services are commonly used as legitimate technical support software, and may be whitelisted within a target environment. Remote access tools like VNC, Ammy, and Teamviewer are used frequently when compared with other legitimate software commonly used by adversaries.1

Remote access tools may be established and used post-compromise as alternate communications channel for Redundant Access or as a way to establish an interactive remote desktop session with the target system. They may also be used as a component of malware to establish a reverse connection or back-connect to a service or adversary controlled system.

Admin tools such as TeamViewer have been used by several groups targeting institutions in countries of interest to the Russian state and criminal campaigns.23

Examples

  • Carbanak used legitimate programs such as AmmyAdmin and Team Viewer for remote interactive C2 to target systems.4

Mitigation

Properly configure firewalls, application firewalls, and proxies to limit outgoing traffic to sites and services used by remote access tools.

Network intrusion detection and prevention systems that use network signatures may be able to prevent traffic to these services as well.

Use application whitelisting to mitigate use of and installation of unapproved software.

Detection

Monitor for applications and processes related to remote admin tools. Correlate activity with other suspicious behavior that may reduce false positives if these tools are used by legitimate users and administrators.

Analyze network data for uncommon data flows (e.g., a client sending significantly more data than it receives from a server). Processes utilizing the network that do not normally have network communication or have never been seen before are suspicious. Analyze packet contents to detect application layer protocols that do not follow the expected protocol for the port that is being used.

Domain Fronting may be used in conjunction to avoid defenses. Adversaries will likely need to deploy and/or install these remote tools to compromised systems. It may be possible to detect or prevent the installation of these tools with host-based solutions.