Failed Logon From Public IP

calendar Oct 23, 2025 · attack.privilege-escalation attack.defense-evasion attack.initial-access attack.persistence attack.t1078 attack.t1190 attack.t1133  ·
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Detects a failed logon attempt from a public IP. A login from a public IP can indicate a misconfigured firewall or network boundary.

Sigma rule (View on GitHub)

 1title: Failed Logon From Public IP
 2id: f88e112a-21aa-44bd-9b01-6ee2a2bbbed1
 3status: test
 4description: Detects a failed logon attempt from a public IP. A login from a public IP can indicate a misconfigured firewall or network boundary.
 5references:
 6    - https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/auditing/event-4625
 7author: NVISO
 8date: 2020-05-06
 9modified: 2024-03-11
10tags:
11    - attack.privilege-escalation
12    - attack.defense-evasion
13    - attack.initial-access
14    - attack.persistence
15    - attack.t1078
16    - attack.t1190
17    - attack.t1133
18logsource:
19    product: windows
20    service: security
21detection:
22    selection:
23        EventID: 4625
24    filter_main_ip_unknown:
25        IpAddress|contains: '-'
26    filter_main_local_ranges:
27        IpAddress|cidr:
28            - '::1/128'  # IPv6 loopback
29            - '10.0.0.0/8'
30            - '127.0.0.0/8'
31            - '172.16.0.0/12'
32            - '192.168.0.0/16'
33            - '169.254.0.0/16'
34            - 'fc00::/7'  # IPv6 private addresses
35            - 'fe80::/10'  # IPv6 link-local addresses
36    condition: selection and not 1 of filter_main_*
37falsepositives:
38    - Legitimate logon attempts over the internet
39    - IPv4-to-IPv6 mapped IPs
40level: medium

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