Failed Logon From Public IP

 1title: Failed Logon From Public IP
 2id: f88e112a-21aa-44bd-9b01-6ee2a2bbbed1
 3status: test
 4description: A login from a public IP can indicate a misconfigured firewall or network boundary.
 5author: NVISO
 6date: 2020/05/06
 7modified: 2023/01/11
 8tags:
 9    - attack.initial_access
10    - attack.persistence
11    - attack.t1078
12    - attack.t1190
13    - attack.t1133
14logsource:
15    product: windows
16    service: security
17detection:
18    selection:
19        EventID: 4625
20    filter_ip_unknown:
21        IpAddress|contains: '-'
22    filter_ip_privatev4:
23        IpAddress|startswith:
24            - '10.' #10.0.0.0/8
25            - '192.168.' #192.168.0.0/16
26            - '172.16.' #172.16.0.0/12
27            - '172.17.'
28            - '172.18.'
29            - '172.19.'
30            - '172.20.'
31            - '172.21.'
32            - '172.22.'
33            - '172.23.'
34            - '172.24.'
35            - '172.25.'
36            - '172.26.'
37            - '172.27.'
38            - '172.28.'
39            - '172.29.'
40            - '172.30.'
41            - '172.31.'
42            - '127.' #127.0.0.0/8
43            - '169.254.' #169.254.0.0/16
44    filter_ip_privatev6:
45        - IpAddress: '::1' #loopback
46        - IpAddress|startswith:
47            - 'fe80::' #link-local
48            - 'fc00::' #unique local
49    condition: selection and not 1 of filter_*
50falsepositives:
51    - Legitimate logon attempts over the internet
52    - IPv4-to-IPv6 mapped IPs
53level: medium