External Remote SMB Logon from Public IP

calendar Oct 23, 2025 · attack.privilege-escalation attack.persistence attack.defense-evasion attack.initial-access attack.credential-access attack.t1133 attack.t1078 attack.t1110  ·
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Detects successful logon from public IP address via SMB. This can indicate a publicly-exposed SMB port.

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 1title: External Remote SMB Logon from Public IP
 2id: 78d5cab4-557e-454f-9fb9-a222bd0d5edc
 3related:
 4    - id: 259a9cdf-c4dd-4fa2-b243-2269e5ab18a2
 5      type: derived
 6status: test
 7description: Detects successful logon from public IP address via SMB. This can indicate a publicly-exposed SMB port.
 8references:
 9    - https://www.inversecos.com/2020/04/successful-4624-anonymous-logons-to.html
10    - https://twitter.com/Purp1eW0lf/status/1616144561965002752
11author: Micah Babinski (@micahbabinski), Zach Mathis (@yamatosecurity)
12date: 2023-01-19
13modified: 2024-03-11
14tags:
15    - attack.privilege-escalation
16    - attack.persistence
17    - attack.defense-evasion
18    - attack.initial-access
19    - attack.credential-access
20    - attack.t1133
21    - attack.t1078
22    - attack.t1110
23logsource:
24    product: windows
25    service: security
26detection:
27    selection:
28        EventID: 4624
29        LogonType: 3
30    filter_main_local_ranges:
31        IpAddress|cidr:
32            - '::1/128'  # IPv6 loopback
33            - '10.0.0.0/8'
34            - '127.0.0.0/8'
35            - '172.16.0.0/12'
36            - '192.168.0.0/16'
37            - '169.254.0.0/16'
38            - 'fc00::/7'  # IPv6 private addresses
39            - 'fe80::/10'  # IPv6 link-local addresses
40    filter_main_empty:
41        IpAddress: '-'
42    condition: selection and not 1 of filter_main_*
43falsepositives:
44    - Legitimate or intentional inbound connections from public IP addresses on the SMB port.
45level: high

References

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