Detection rules › Sigma

NTFS symbolic link configuration change

Status
experimental
Severity
medium
Log source
product windows, category process_creation
Author
mdecrevoisier
Source
github.com/mdecrevoisier/SIGMA-detection-rules

Detects scenarios where an attacker attempts to modify the type of symbolic link than can be created.

MITRE ATT&CK coverage

Event coverage

Rule body yaml

title: NTFS symbolic link configuration change
description: Detects scenarios where an attacker attempts to modify the type of symbolic link than can be created.
references:
- https://news.sophos.com/en-us/2022/08/10/lockbit-hive-and-blackcat-attack-automotive-supplier-in-triple-ransomware-attack/
- https://www.microsoft.com/en-us/security/blog/2022/06/13/the-many-lives-of-blackcat-ransomware/
- https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/fsutil-behavior
tags:
- attack.persistence
- attack.t1547.009 # Boot or Logon Autostart Execution: Shortcut Modification 
author: mdecrevoisier
status: experimental
logsource:
  product: windows
  category: process_creation
detection: # 'fsutil behavior set SymlinkEvaluation R2L:1'
  selection:
    NewProcessName|endswith: '\fsutil.exe'
    CommandLine|contains|all:
      - behavior
      - set
  condition: selection
falsepositives:
- admin activity on file server
level: medium

Stages and Predicates

Stage 0: condition

selection

Stage 1: selection

selection:
  NewProcessName|endswith: '\fsutil.exe'
  CommandLine|contains|all:
    - behavior
    - set

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
  • behavior corpus 3 (sigma 2, splunk 1)
  • set corpus 11 (sigma 10, splunk 1)
NewProcessNameends_with
  • \fsutil.exe corpus 5 (sigma 5)