Potentially Suspicious NTFS Symlink Behavior Modification

testmedium
Log-Quelle: windows · process_creationAutor frack113, The DFIR ReportDatum 2022-03-02
01

Beschreibung

Was dies ist, in Kürze.

Detects the modification of NTFS symbolic link behavior using fsutil, which could be used to enable remote to local or remote to remote symlinks for potential attacks.

02

Tags

attack.executionattack.defense-impairmentattack.t1059attack.t1222.001
03

Regelquelle (YAML)

title: Potentially Suspicious NTFS Symlink Behavior Modification
id: c0b2768a-dd06-4671-8339-b16ca8d1f27f
status: test
description: |
    Detects the modification of NTFS symbolic link behavior using fsutil, which could be used to enable remote to local or remote to remote symlinks for potential attacks.
references:
    - https://www.cybereason.com/blog/cybereason-vs.-blackcat-ransomware
    - https://learn.microsoft.com/fr-fr/windows-server/administration/windows-commands/fsutil-behavior
    - https://thedfirreport.com/2025/06/30/hide-your-rdp-password-spray-leads-to-ransomhub-deployment/
author: frack113, The DFIR Report
date: 2022-03-02
modified: 2025-11-13
tags:
    - attack.execution
    - attack.defense-impairment
    - attack.t1059
    - attack.t1222.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img_proxy:
        # Note: Example command observed:  cmd.exe /c "fsutil behaviour set SymlinkEvaluation"
        - Image|endswith:
              - '\cmd.exe'
              - '\powershell.exe'
              - '\pwsh.exe'
        - OriginalFileName:
              - 'Cmd.Exe'
              - 'PowerShell.EXE'
              - 'pwsh.dll'
    selection_fsutil_cli:
        CommandLine|contains|all:
            - 'fsutil'
            - 'behavior'
            - 'set'
            - 'SymlinkEvaluation'
    selection_symlink_params:
        CommandLine|contains:
            - 'R2L:1' # Remote to Local
            - 'R2R:1' # Remote to Remote
            - 'L2L:1' # Local to Local
    condition: all of selection_*
falsepositives:
    - Legitimate usage, investigate the parent process and context to determine if benign.
level: medium
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_fsutil_symlinkevaluation/info.yml
04

erkennt Techniken (2)

ATT&CK-Techniken, die dies ermöglicht oder abbildet.

05

Referenzen

Externe Belege — Patches, Meldungen, Analysen.