VNC (Virtual Network Computing) to the Internet

 1[metadata]
 2creation_date = "2020/02/18"
 3integration = ["network_traffic"]
 4maturity = "production"
 5min_stack_comments = "New fields added: required_fields, related_integrations, setup"
 6min_stack_version = "8.3.0"
 7updated_date = "2023/08/17"
 8
 9[rule]
10author = ["Elastic"]
11description = """
12This rule detects network events that may indicate the use of VNC traffic to the Internet. VNC is commonly used by
13system administrators to remotely control a system for maintenance or to use shared resources. It should almost never be
14directly exposed to the Internet, as it is frequently targeted and exploited by threat actors as an initial access or
15backdoor vector.
16"""
17false_positives = [
18    """
19    VNC connections may be made directly to Linux cloud server instances but such connections are usually made only by
20    engineers. VNC is less common than SSH or RDP but may be required by some work flows such as remote access and
21    support for specialized software products or servers. Such work-flows are usually known and not unexpected. Usage
22    that is unfamiliar to server or network owners can be unexpected and suspicious.
23    """,
24]
25from = "now-9m"
26index = ["packetbeat-*", "auditbeat-*", "filebeat-*", "logs-network_traffic.*"]
27language = "kuery"
28license = "Elastic License v2"
29name = "VNC (Virtual Network Computing) to the Internet"
30references = ["https://www.iana.org/assignments/iana-ipv4-special-registry/iana-ipv4-special-registry.xhtml"]
31risk_score = 47
32rule_id = "3ad49c61-7adc-42c1-b788-732eda2f5abf"
33severity = "medium"
34tags = ["Tactic: Command and Control", "Domain: Endpoint", "Use Case: Threat Detection"]
35timestamp_override = "event.ingested"
36type = "query"
37
38query = '''
39(event.dataset: network_traffic.flow  or (event.category: (network or network_traffic))) and
40  network.transport:tcp and destination.port >= 5800 and destination.port <= 5810 and
41  source.ip:(
42    10.0.0.0/8 or
43    172.16.0.0/12 or
44    192.168.0.0/16
45  ) and
46  not destination.ip:(
47    10.0.0.0/8 or
48    127.0.0.0/8 or
49    169.254.0.0/16 or
50    172.16.0.0/12 or
51    192.0.0.0/24 or
52    192.0.0.0/29 or
53    192.0.0.8/32 or
54    192.0.0.9/32 or
55    192.0.0.10/32 or
56    192.0.0.170/32 or
57    192.0.0.171/32 or
58    192.0.2.0/24 or
59    192.31.196.0/24 or
60    192.52.193.0/24 or
61    192.168.0.0/16 or
62    192.88.99.0/24 or
63    224.0.0.0/4 or
64    100.64.0.0/10 or
65    192.175.48.0/24 or
66    198.18.0.0/15 or
67    198.51.100.0/24 or
68    203.0.113.0/24 or
69    240.0.0.0/4 or
70    "::1" or
71    "FE80::/10" or
72    "FF00::/8"
73  )
74'''
75
76
77[[rule.threat]]
78framework = "MITRE ATT&CK"
79[[rule.threat.technique]]
80id = "T1219"
81name = "Remote Access Software"
82reference = "https://attack.mitre.org/techniques/T1219/"
83
84
85[rule.threat.tactic]
86id = "TA0011"
87name = "Command and Control"
88reference = "https://attack.mitre.org/tactics/TA0011/"