New Custom Shim Database Created — Sigma Rule

Rule metadata and linked tags

Author: frack113, Nasreddine Bencherchali (Nextron Systems). Source status: test; severity: medium. Source dates: 2021-12-29 / 2023-12-06.

{
  "product": "windows",
  "category": "file_event"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: edb704b6b6ca85e556dd3257bd569c8cc4086c65b66d55c641ae3eac97bd207e

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: New Custom Shim Database Created
id: ee63c85c-6d51-4d12-ad09-04e25877a947
status: test
description: |
    Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by application shims.
    The Microsoft Windows Application Compatibility Infrastructure/Framework (Application Shim) was created to allow for backward compatibility of software as the operating system codebase changes over time.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1546.011/T1546.011.md#atomic-test-2---new-shim-database-files-created-in-the-default-shim-database-directory
    - https://www.mandiant.com/resources/blog/fin7-shim-databases-persistence
    - https://liberty-shell.com/sec/2020/02/25/shim-persistence/
    - https://andreafortuna.org/2018/11/12/process-injection-and-persistence-using-application-shimming/
author: frack113, Nasreddine Bencherchali (Nextron Systems)
date: 2021-12-29
modified: 2023-12-06
tags:
    - attack.privilege-escalation
    - attack.persistence
    - attack.t1547.009
logsource:
    product: windows
    category: file_event
detection:
    selection:
        TargetFilename|contains:
            - ':\Windows\apppatch\Custom\'
            - ':\Windows\apppatch\CustomSDB\'
    condition: selection
falsepositives:
    - Legitimate custom SHIM installations will also trigger this rule
level: medium
regression_tests_path: regression_data/rules/windows/file/file_event/file_event_win_creation_new_shim_database/info.yml

Original YAML and metadata in JSON

False positives

• Legitimate custom SHIM installations will also trigger this rule

Source references

• https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1546.011/T1546.011.md#atomic-test-2---new-shim-database-files-created-in-the-default-shim-database-directory
• https://www.mandiant.com/resources/blog/fin7-shim-databases-persistence
• https://liberty-shell.com/sec/2020/02/25/shim-persistence/
• https://andreafortuna.org/2018/11/12/process-injection-and-persistence-using-application-shimming/