VNC (Virtual Network Computing) from the Internet

 1[metadata]
 2creation_date = "2020/02/18"
 3integration = ["network_traffic"]
 4maturity = "production"
 5updated_date = "2024/05/21"
 6
 7[rule]
 8author = ["Elastic"]
 9description = """
10This rule detects network events that may indicate the use of VNC traffic from the Internet. VNC is commonly used by
11system administrators to remotely control a system for maintenance or to use shared resources. It should almost never be
12directly exposed to the Internet, as it is frequently targeted and exploited by threat actors as an initial access or
13backdoor vector.
14"""
15false_positives = [
16    """
17    VNC connections may be received directly to Linux cloud server instances but such connections are usually made only
18    by engineers. VNC is less common than SSH or RDP but may be required by some work-flows such as remote access and
19    support for specialized software products or servers. Such work-flows are usually known and not unexpected. Usage
20    that is unfamiliar to server or network owners can be unexpected and suspicious.
21    """,
22]
23from = "now-9m"
24index = ["packetbeat-*", "auditbeat-*", "filebeat-*", "logs-network_traffic.*"]
25language = "kuery"
26license = "Elastic License v2"
27name = "VNC (Virtual Network Computing) from the Internet"
28references = ["https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml"]
29risk_score = 73
30rule_id = "5700cb81-df44-46aa-a5d7-337798f53eb8"
31severity = "high"
32tags = ["Tactic: Command and Control", "Domain: Endpoint", "Use Case: Threat Detection"]
33timestamp_override = "event.ingested"
34type = "query"
35
36query = '''
37(event.dataset: network_traffic.flow or (event.category: (network or network_traffic))) and
38  network.transport:tcp and destination.port >= 5800 and destination.port <= 5810 and
39  not source.ip:(
40    10.0.0.0/8 or
41    127.0.0.0/8 or
42    169.254.0.0/16 or
43    172.16.0.0/12 or
44    192.0.0.0/24 or
45    192.0.0.0/29 or
46    192.0.0.8/32 or
47    192.0.0.9/32 or
48    192.0.0.10/32 or
49    192.0.0.170/32 or
50    192.0.0.171/32 or
51    192.0.2.0/24 or
52    192.31.196.0/24 or
53    192.52.193.0/24 or
54    192.168.0.0/16 or
55    192.88.99.0/24 or
56    224.0.0.0/4 or
57    100.64.0.0/10 or
58    192.175.48.0/24 or
59    198.18.0.0/15 or
60    198.51.100.0/24 or
61    203.0.113.0/24 or
62    240.0.0.0/4 or
63    "::1" or
64    "FE80::/10" or
65    "FF00::/8"
66  ) and
67  destination.ip:(
68    10.0.0.0/8 or
69    172.16.0.0/12 or
70    192.168.0.0/16
71  )
72'''
73
74
75[[rule.threat]]
76framework = "MITRE ATT&CK"
77[[rule.threat.technique]]
78id = "T1219"
79name = "Remote Access Software"
80reference = "https://attack.mitre.org/techniques/T1219/"
81
82
83[rule.threat.tactic]
84id = "TA0011"
85name = "Command and Control"
86reference = "https://attack.mitre.org/tactics/TA0011/"
87[[rule.threat]]
88framework = "MITRE ATT&CK"
89[[rule.threat.technique]]
90id = "T1190"
91name = "Exploit Public-Facing Application"
92reference = "https://attack.mitre.org/techniques/T1190/"
93
94
95[rule.threat.tactic]
96id = "TA0001"
97name = "Initial Access"
98reference = "https://attack.mitre.org/tactics/TA0001/"