Cross-source coverage

T1021.005 / ATT&CK

Remote Services: VNC

3 rules across 3 sources.

From MITRE ATT&CK 19.2

Adversaries may use Valid Accounts to remotely control machines using Virtual Network Computing (VNC). VNC is a platform-independent desktop sharing system that uses the RFB (“remote framebuffer”) protocol to enable users to remotely control another computer’s display by relaying the screen, mouse, and keyboard inputs over the network.

VNC differs from Remote Desktop Protocol as VNC is screen-sharing software rather than resource-sharing software. By default, VNC uses the system's authentication, but it can be configured to use credentials specific to VNC.

Adversaries may abuse VNC to perform malicious actions as the logged-on user such as opening documents, downloading files, and running arbitrary commands. An adversary could use VNC to remotely control and monitor a system to collect data and information to pivot to other systems within the network. Specific VNC libraries/implementations have also been susceptible to brute force attacks and memory usage exploitation.

Platforms
Linux · Windows · macOS
Telemetry
WinEventLog:SysmonWinEventLog:SecurityNSM:Flowauditd:EXECVElinux:syslogmacos:unifiedlogmacos:osqueryNSM:firewall

How MITRE says to detect it DET0178

Behavioral Detection of Unauthorized VNC Remote Control Sessions

Windows Analytic 0504

Detection of VNC service or executable starting unexpectedly, followed by user session creation and interactive desktop activity (mouse/keyboard simulation).

  • WinEventLog:Sysmon EventCode=1
  • WinEventLog:Security EventCode=4624, 4648
  • NSM:Flow port 5900 inbound

Linux Analytic 0505

Spawning of VNC-related processes (e.g., `x11vnc`, `vncserver`) coupled with authentication logs and port listening behavior on TCP 5900.

  • auditd:EXECVE None
  • linux:syslog None
  • NSM:Flow TCP port 5900 open

macOS Analytic 0506

Detection of VNC-based remote control via `screensharingd` activity in Unified Logs along with concurrent remote login activity or suspicious user interaction.

  • macos:unifiedlog authentication
  • macos:osquery process_events
  • NSM:firewall inbound connection to port 5900

View on attack.mitre.org ↗

SigmaHQ/sigma

1 rule
Detection Severity Format
Suspicious UltraVNC Execution High Sigma

elastic/detection-rules

1 rule
Detection Severity Format
VNC (Virtual Network Computing) to the Internet Medium Elastic TOML

panther-labs/panther-analysis

1 rule
Detection Severity Format
AWS EC2 Multi Instance Connect Informational Panther Python

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