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Detection rules › Sigma

File Deletion Via Del

Status
test
Severity
low
Log source
product windows, category process_creation
Author
frack113
Source
github.com/SigmaHQ/sigma

Detects execution of the builtin "del"/"erase" commands in order to delete files. Adversaries may delete files left behind by the actions of their intrusion activity. Malware, tools, or other non-native files dropped or created on a system by an adversary may leave traces to indicate to what was done within a network and how. Removal of these files can occur during an intrusion, or as part of a post-intrusion process to minimize the adversary's footprint.

MITRE ATT&CK coverage

TacticTechniques
StealthT1070.004 Indicator Removal: File Deletion

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: File Deletion Via Del
id: 379fa130-190e-4c3f-b7bc-6c8e834485f3
status: test
description: |
    Detects execution of the builtin "del"/"erase" commands in order to delete files.
    Adversaries may delete files left behind by the actions of their intrusion activity.
    Malware, tools, or other non-native files dropped or created on a system by an adversary may leave traces to indicate to what was done within a network and how.
    Removal of these files can occur during an intrusion, or as part of a post-intrusion process to minimize the adversary's footprint.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1070.004/T1070.004.md
    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/erase
author: frack113
date: 2022-01-15
modified: 2024-03-05
tags:
    - attack.stealth
    - attack.t1070.004
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\cmd.exe'
        - OriginalFileName: 'Cmd.Exe'
    selection_del:
        CommandLine|contains:
            - 'del '
            - 'erase '
    selection_flags:
        CommandLine|contains|windash:
            - ' -f' # Force deleting of read-only files.
            - ' -s' # Delete specified files from all subdirectories.
            - ' -q' # Quiet mode, do not ask if ok to delete on global wildcard
    condition: all of selection_*
falsepositives:
    - False positives levels will differ Depending on the environment. You can use a combination of ParentImage and other keywords from the CommandLine field to filter legitimate activity
level: low

Stages and Predicates

Stage 0: condition

all of selection_*

Stage 1: selection_img

selection_img:
    - Image|endswith: '\cmd.exe'
    - OriginalFileName: 'Cmd.Exe'

Stage 2: selection_del

selection_del:
    CommandLine|contains:
        - 'del '
        - 'erase '

Stage 3: selection_flags

selection_flags:
    CommandLine|contains|windash:
        - ' -f'
        - ' -s'
        - ' -q'

Indicators

Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.

FieldKindValues
CommandLinematch
  • -f transforms: windash corpus 4 (sigma 3, chronicle 1)
  • -q transforms: windash
  • -s transforms: windash corpus 3 (sigma 3)
  • del corpus 5 (sigma 5)
  • erase corpus 3 (sigma 3)
Imageends_with
  • \cmd.exe corpus 130 (sigma 130)
OriginalFileNameeq
  • Cmd.Exe corpus 65 (sigma 43, splunk 17, elastic 5)