Failed Logon From Public IP

 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.initial-access
12    - attack.persistence
13    - attack.t1078
14    - attack.t1190
15    - attack.t1133
16logsource:
17    product: windows
18    service: security
19detection:
20    selection:
21        EventID: 4625
22    filter_main_ip_unknown:
23        IpAddress|contains: '-'
24    filter_main_local_ranges:
25        IpAddress|cidr:
26            - '::1/128'  # IPv6 loopback
27            - '10.0.0.0/8'
28            - '127.0.0.0/8'
29            - '172.16.0.0/12'
30            - '192.168.0.0/16'
31            - '169.254.0.0/16'
32            - 'fc00::/7'  # IPv6 private addresses
33            - 'fe80::/10'  # IPv6 link-local addresses
34    condition: selection and not 1 of filter_main_*
35falsepositives:
36    - Legitimate logon attempts over the internet
37    - IPv4-to-IPv6 mapped IPs
38level: medium