LSASS Process Reconnaissance Via Findstr.EXE

Status: test
Severity: high
Log source: category process_creation, product windows
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

Tactic	Techniques
Credential Access	`T1552.006` Unsecured Credentials: Group Policy Preferences

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

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

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`/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 10 (sigma 6, kusto 2, elastic 1, chronicle 1)	`field:"CommandLine" kind:match`
`Image`	ends_with	`\find.exe` corpus 7 (sigma 7) `\findstr.exe` corpus 11 (sigma 11)	`field:"Image" kind:ends_with`
`OriginalFileName`	eq	`FIND.EXE` corpus 7 (sigma 7) `FINDSTR.EXE` corpus 12 (sigma 12)	`field:"OriginalFileName" kind:eq`

LSASS Process Reconnaissance Via Findstr.EXE

MITRE ATT&CK coverage

Telemetry coverage

Rule body

Stages and Predicates

Stage 0: condition

Stage 1: selection_findstr_img

Stage 2: selection_findstr_cli

Stage 3: selection_special

Indicators

Stage 0: `condition`

Stage 1: `selection_findstr_img`

Stage 2: `selection_findstr_cli`

Stage 3: `selection_special`