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Detection rules › Sigma

LSASS Process Reconnaissance Via Findstr.EXE

Status
test
Severity
high
Log source
product windows, category process_creation
Author
Florian Roth (Nextron Systems)
Source
github.com/SigmaHQ/sigma

Detects findstring commands that include the keyword lsass, which indicates recon actviity for the LSASS process PID

MITRE ATT&CK coverage

TacticTechniques
Credential AccessT1552.006 Unsecured Credentials: Group Policy Preferences

Event coverage

ProviderEventTitle
SysmonEvent ID 1Process creation

Rule body yaml

title: LSASS Process Reconnaissance Via Findstr.EXE
id: fe63010f-8823-4864-a96b-a7b4a0f7b929
status: test
description: Detects findstring commands that include the keyword lsass, which indicates recon actviity for the LSASS process PID
references:
    - https://blog.talosintelligence.com/2022/08/recent-cyber-attack.html?m=1
author: Florian Roth (Nextron Systems)
date: 2022-08-12
modified: 2024-06-04
tags:
    - attack.credential-access
    - attack.t1552.006
logsource:
    category: process_creation
    product: windows
detection:
    selection_findstr_img:
        - Image|endswith:
              - '\find.exe'
              - '\findstr.exe'
        - OriginalFileName:
              - 'FIND.EXE'
              - 'FINDSTR.EXE'
    selection_findstr_cli:
        CommandLine|contains: 'lsass'
    selection_special:
        CommandLine|contains|windash:
            - ' /i "lsass'
            - ' /i lsass.exe'
            - 'findstr "lsass'
            - 'findstr lsass'
            - 'findstr.exe "lsass'
            - 'findstr.exe lsass'
    condition: all of selection_findstr_* or selection_special
falsepositives:
    - Unknown
level: high
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_findstr_lsass/info.yml

Stages and Predicates

Stage 0: condition

all of selection_findstr_* or selection_special

Stage 1: selection_findstr_img

selection_findstr_img:
    - Image|endswith:
          - '\find.exe'
          - '\findstr.exe'
    - OriginalFileName:
          - 'FIND.EXE'
          - 'FINDSTR.EXE'

Stage 2: selection_findstr_cli

selection_findstr_cli:
    CommandLine|contains: 'lsass'

Stage 3: selection_special

selection_special:
    CommandLine|contains|windash:
        - ' /i "lsass'
        - ' /i lsass.exe'
        - 'findstr "lsass'
        - 'findstr lsass'
        - 'findstr.exe "lsass'
        - 'findstr.exe lsass'

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
  • /i "lsass transforms: windash
  • /i lsass.exe transforms: windash
  • findstr "lsass transforms: windash
  • findstr lsass transforms: windash
  • findstr.exe "lsass transforms: windash
  • findstr.exe lsass transforms: windash
  • lsass corpus 9 (sigma 6, kusto 2, chronicle 1)
Imageends_with
  • \find.exe corpus 8 (sigma 8)
  • \findstr.exe corpus 12 (sigma 12)
OriginalFileNameeq
  • FIND.EXE corpus 7 (sigma 7)
  • FINDSTR.EXE corpus 12 (sigma 12)