Set Suspicious Files as System Files Using Attrib.EXE

Detects the usage of attrib with the "+s" option to set scripts or executables located in suspicious locations as system files to hide them from users and make them unable to be deleted with simple rights. The rule limits the search to specific extensions and directories to avoid FPs

Sigma rule (View on GitHub)

 1title: Set Suspicious Files as System Files Using Attrib.EXE
 2id: efec536f-72e8-4656-8960-5e85d091345b
 3related:
 4    - id: bb19e94c-59ae-4c15-8c12-c563d23fe52b
 5      type: derived
 6status: test
 7description: |
 8        Detects the usage of attrib with the "+s" option to set scripts or executables located in suspicious locations as system files to hide them from users and make them unable to be deleted with simple rights. The rule limits the search to specific extensions and directories to avoid FPs
 9references:
10    - https://app.any.run/tasks/c28cabc8-a19f-40f3-a78b-cae506a5c0d4
11    - https://app.any.run/tasks/cfc8870b-ccd7-4210-88cf-a8087476a6d0
12    - https://unit42.paloaltonetworks.com/unit42-sure-ill-take-new-combojack-malware-alters-clipboards-steal-cryptocurrency/
13author: Nasreddine Bencherchali (Nextron Systems)
14date: 2022/06/28
15modified: 2023/03/14
16tags:
17    - attack.defense_evasion
18    - attack.t1564.001
19logsource:
20    category: process_creation
21    product: windows
22detection:
23    selection_img:
24        - Image|endswith: '\attrib.exe'
25        - OriginalFileName: 'ATTRIB.EXE'
26    selection_cli:
27        CommandLine|contains: ' +s'
28    selection_paths:
29        CommandLine|contains:
30            - ' %' # Custom Environment variable
31            - '\Users\Public\'
32            - '\AppData\Local\'
33            - '\ProgramData\'
34            - '\Downloads\'
35            - '\Windows\Temp\'
36    selection_ext:
37        CommandLine|contains:
38            - '.bat'
39            - '.dll'
40            - '.exe'
41            - '.hta'
42            - '.ps1'
43            - '.vbe'
44            - '.vbs'
45    filter:
46        CommandLine|contains|all:
47            - '\Windows\TEMP\'
48            - '.exe'
49    condition: all of selection* and not filter
50falsepositives:
51    - Unknown
52level: high

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