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Detection rules › Sigma

DD File Overwrite

Status
test
Severity
low
Log source
category process_creation, product linux
Author
Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC
Source
github.com/SigmaHQ/sigma

Detects potential overwriting and deletion of a file using DD.

Known false positives

  • Any user deleting files that way.

MITRE ATT&CK coverage

TacticTechniques
Impact

Telemetry coverage

PlatformRecord / event type
LinuxEvent ID 1: Process Create

Rule body

title: DD File Overwrite
id: 2953194b-e33c-4859-b9e8-05948c167447
status: test
description: Detects potential overwriting and deletion of a file using DD.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1485/T1485.md#atomic-test-2---macoslinux---overwrite-file-with-dd
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research), MSTIC
date: 2021-10-15
modified: 2022-07-07
tags:
    - attack.impact
    - attack.t1485
logsource:
    product: linux
    category: process_creation
detection:
    selection1:
        Image:
            - '/bin/dd'
            - '/usr/bin/dd'
    selection2:
        CommandLine|contains: 'of='
    selection3:
        CommandLine|contains:
            - 'if=/dev/zero'
            - 'if=/dev/null'
    condition: all of selection*
falsepositives:
    - Any user deleting files that way.
level: low

Stages and Predicates

Stage 0: condition

all of selection*

Stage 1: selection1

selection1:
    Image:
        - '/bin/dd'
        - '/usr/bin/dd'

Stage 2: selection2

selection2:
    CommandLine|contains: 'of='

Stage 3: selection3

selection3:
    CommandLine|contains:
        - 'if=/dev/zero'
        - 'if=/dev/null'

Indicators

These rows show field, operator, and value matches.

FieldKindValuesSearch
CommandLinematch
  • if=/dev/null
  • if=/dev/zero
  • of=
field:"CommandLine" kind:match
Imageeq
  • /bin/dd
  • /usr/bin/dd
field:"Image" kind:eq