Local System Accounts Discovery - Linux

Detects enumeration of local systeam accounts. This information can help adversaries determine which local accounts exist on a system to aid in follow-on behavior.

Sigma rule (View on GitHub)

 1title: Local System Accounts Discovery - Linux
 2id: b45e3d6f-42c6-47d8-a478-df6bd6cf534c
 3status: test
 4description: Detects enumeration of local systeam accounts. This information can help adversaries determine which local accounts exist on a system to aid in follow-on behavior.
 5references:
 6    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1087.001/T1087.001.md
 7    - https://my.f5.com/manage/s/article/K589
 8    - https://man.freebsd.org/cgi/man.cgi?pwd_mkdb
 9author: Alejandro Ortuno, oscd.community, CheraghiMilad
10date: 2020-10-08
11modified: 2024-12-10
12tags:
13    - attack.discovery
14    - attack.t1087.001
15logsource:
16    category: process_creation
17    product: linux
18detection:
19    selection_1:
20        Image|endswith: '/lastlog'
21    selection_2:
22        CommandLine|contains: '''x:0:'''
23    selection_3:
24        Image|endswith:
25            - '/cat'
26            - '/ed'
27            - '/head'
28            - '/more'
29            - '/nano'
30            - '/tail'
31            - '/vi'
32            - '/vim'
33            - '/less'
34            - '/emacs'
35            - '/sqlite3'
36            - '/makemap'
37        CommandLine|contains:
38            - '/etc/passwd'
39            - '/etc/shadow'
40            - '/etc/sudoers'
41            - '/etc/spwd.db'
42            - '/etc/pwd.db'
43            - '/etc/master.passwd'
44    selection_4:
45        Image|endswith: '/id'
46    selection_5:
47        Image|endswith: '/lsof'
48        CommandLine|contains: '-u'
49    condition: 1 of selection*
50falsepositives:
51    - Legitimate administration activities
52level: low

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