VNC (Virtual Network Computing) from the Internet

Last updated 8 months ago on 2025-05-05

Created 6 years ago on 2020-02-18

About

This rule 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 backdoor vector.

Tags

Tactic: Command and ControlDomain: EndpointUse Case: Threat DetectionData Source: PAN-OSLanguage: kuery

Severity

high

Risk Score

MITRE ATT&CK™

Command and Control (TA0011)(external, opens in a new tab or window)

↳ Remote Access Tools (T1219)(external, opens in a new tab or window)

Initial Access (TA0001)(external, opens in a new tab or window)

↳ Exploit Public-Facing Application (T1190)(external, opens in a new tab or window)

False Positive Examples

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 work-flows such as remote access and support for specialized software products or servers. Such work-flows are usually known and not unexpected. Usage that is unfamiliar to server or network owners can be unexpected and suspicious.

License

Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type

Query (Kibana Query Language)

Integration Pack

Prebuilt Security Detection Rules

Index Patterns

packetbeat-*auditbeat-*filebeat-*logs-network_traffic.*logs-panw.panos*

Related Integrations

network_traffic(external, opens in a new tab or window)

panw(external, opens in a new tab or window)

Query

✄𐘗text code block:
✄𐘗(event.dataset: network_traffic.flow or (event.category: (network or network_traffic))) and
  network.transport:tcp and destination.port >= 5800 and destination.port <= 5810 and
  not source.ip:(
    10.0.0.0/8 or
    127.0.0.0/8 or
    169.254.0.0/16 or
    172.16.0.0/12 or
    192.0.0.0/24 or
    192.0.0.0/29 or
    192.0.0.8/32 or
    192.0.0.9/32 or
    192.0.0.10/32 or
    192.0.0.170/32 or
    192.0.0.171/32 or
    192.0.2.0/24 or
    192.31.196.0/24 or
    192.52.193.0/24 or
    192.168.0.0/16 or
    192.88.99.0/24 or
    224.0.0.0/4 or
    100.64.0.0/10 or
    192.175.48.0/24 or
    198.18.0.0/15 or
    198.51.100.0/24 or
    203.0.113.0/24 or
    240.0.0.0/4 or
    "::1" or
    "FE80::/10" or
    "FF00::/8"
  ) and
  destination.ip:(
    10.0.0.0/8 or
    172.16.0.0/12 or
    192.168.0.0/16
  )

Install detection rules in Elastic Security

Detect VNC (Virtual Network Computing) from the Internet in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).