Forest Blizzard APT - JavaScript Constrained File Creation

Status: test
Severity: medium
Log source: category file_event, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the creation of JavaScript files inside of the DriverStore directory. Forest Blizzard used this to exploit the CVE-2022-38028 vulnerability in Windows Print Spooler service by modifying a JavaScript constraints file and executing it with SYSTEM-level permissions.

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Defense Impairment	`T1685.001` Disable or Modify Tools: Disable or Modify Windows Event Log

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 11: FileCreate

Rule body

title: Forest Blizzard APT - JavaScript Constrained File Creation
id: ec7c4e9b-9bc9-47c7-a32f-b53b598da642
status: test
description: |
    Detects the creation of JavaScript files inside of the DriverStore directory.
    Forest Blizzard used this to exploit the CVE-2022-38028 vulnerability in Windows Print Spooler service by modifying a JavaScript constraints file and executing it with SYSTEM-level permissions.
references:
    - https://www.microsoft.com/en-us/security/blog/2024/04/22/analyzing-forest-blizzards-custom-post-compromise-tool-for-exploiting-cve-2022-38028-to-obtain-credentials/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2024-04-23
tags:
    - attack.defense-impairment
    - attack.t1685.001
    - detection.emerging-threats
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|startswith: 'C:\Windows\System32\DriverStore\FileRepository\'
        TargetFilename|endswith: '\.js'
    condition: selection
falsepositives:
    - Unlikely
level: medium

Stages and Predicates

Stage 0: `condition`

selection

Stage 1: `selection`

selection:
    TargetFilename|startswith: 'C:\Windows\System32\DriverStore\FileRepository\'
    TargetFilename|endswith: '\.js'

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`TargetFilename`	ends_with	`\.js`	`field:"TargetFilename" kind:ends_with value:"\.js"`
`TargetFilename`	starts_with	`C:\Windows\System32\DriverStore\FileRepository\`	`field:"TargetFilename" kind:starts_with value:"C:\Windows\System32\DriverStore\FileRepository\"`