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Detection rules › Sigma

File and Directory Discovery - Linux

Status
test
Severity
informational
Log source
category process_creation, product linux
Author
Daniil Yugoslavskiy, oscd.community, CheraghiMilad
Source
github.com/SigmaHQ/sigma

Detects usage of system utilities such as "find", "tree", "findmnt", etc, to discover files, directories and network shares.

Known false positives

  • Legitimate activities

MITRE ATT&CK coverage

TacticTechniques
Discovery

Telemetry coverage

PlatformRecord / event type
LinuxEvent ID 1: Process Create

Rule body

title: File and Directory Discovery - Linux
id: d3feb4ee-ff1d-4d3d-bd10-5b28a238cc72
status: test
description: |
    Detects usage of system utilities such as "find", "tree", "findmnt", etc, to discover files, directories and network shares.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1083/T1083.md
author: Daniil Yugoslavskiy, oscd.community, CheraghiMilad
date: 2020-10-19
modified: 2024-12-01
tags:
    - attack.discovery
    - attack.t1083
logsource:
    category: process_creation
    product: linux
detection:
    selection_file_with_asterisk:
        Image|endswith: '/file'
        CommandLine|re: '(.){200,}' # execution of the 'file */* *>> /tmp/output.txt' will produce huge commandline
    selection_recursive_ls:
        Image|endswith: '/ls'
        CommandLine|contains: '-R'
    selection_find_execution:
        Image|endswith: '/find'
    selection_tree_execution:
        Image|endswith: '/tree'
    selection_findmnt_execution:
        Image|endswith: '/findmnt'
    selection_locate_execution:
        Image|endswith: '/mlocate'
    condition: 1 of selection_*
falsepositives:
    - Legitimate activities
level: informational

Stages and Predicates

Stage 0: condition

1 of selection_*

Stage 1: selection_file_with_asterisk

selection_file_with_asterisk:
    Image|endswith: '/file'
    CommandLine|re: '(.){200,}'

Stage 2: selection_recursive_ls

selection_recursive_ls:
    Image|endswith: '/ls'
    CommandLine|contains: '-R'

Stage 3: selection_find_execution

selection_find_execution:
    Image|endswith: '/find'

Stage 4: selection_tree_execution

selection_tree_execution:
    Image|endswith: '/tree'

Stage 5: selection_findmnt_execution

selection_findmnt_execution:
    Image|endswith: '/findmnt'

Stage 6: selection_locate_execution

selection_locate_execution:
    Image|endswith: '/mlocate'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • -R
field:"CommandLine" kind:match value:"-R"
CommandLineregex_match
  • (.){200,}
field:"CommandLine" kind:regex_match value:"(.){200,}"
Imageends_with
  • /file
  • /find
  • /findmnt
  • /ls
  • /mlocate
  • /tree
field:"Image" kind:ends_with