VNC (Virtual Network Computing) from the Internetedit
Detects network events that may indicate the use of VNC traffic from the Internet. VNC is commonly used by system administrators to remotely control a system for maintenance or to use shared resources. It should almost never be directly exposed to the Internet, as it is frequently targeted and exploited by threat actors as an initial access or back-door vector.
Rule indices:
- filebeat-*
Severity: high
Risk score: 73
Runs every: 5 minutes
Searches indices from: now-6m (Date Math format, see also Additional look-back time)
Maximum signals per execution: 100
Tags:
- Elastic
- Network
Rule version: 2 (version history)
Added (Elastic Stack release): 7.6.0
Last modified (Elastic Stack release): 7.6.1
Potential false positivesedit
VNC connections may be received directly to Linux cloud server instances but such connections are usually made only by engineers. VNC is less common than SSH or RDP but may be required by some workflows such as remote access and support for specialized software products or servers. Such workflows are usually known and not unexpected. Usage that is unfamiliar to server or network owners can be unexpected and suspicious.
Rule queryedit
network.transport: tcp and (destination.port >= 5800 and destination.port <= 5810) and ( network.direction: inbound or ( not source.ip: (10.0.0.0/8 or 172.16.0.0/12 or 192.168.0.0/16) and destination.ip: (10.0.0.0/8 or 172.16.0.0/12 or 192.168.0.0/16) ) )
Threat mappingedit
Framework: MITRE ATT&CKTM
-
Tactic:
- Name: Command and Control
- ID: TA0011
- Reference URL: https://attack.mitre.org/tactics/TA0011/
-
Technique:
- Name: Remote Access Tools
- ID: T1219
- Reference URL: https://attack.mitre.org/techniques/T1219/
-
Tactic:
- Name: Initial Access
- ID: TA0001
- Reference URL: https://attack.mitre.org/tactics/TA0001/
-
Technique:
- Name: Exploit Public-Facing Application
- ID: T1190
- Reference URL: https://attack.mitre.org/techniques/T1190/