Potential Shim Database Persistence via Sdbinst.EXE

Status: test
Severity: medium
Log source: category process_creation, product windows
Author: Markus Neis
Source: github.com/SigmaHQ/sigma

Detects installation of a new shim using sdbinst.exe. Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by application shims

MITRE ATT&CK coverage

Tactic	Techniques
Persistence	`T1546.011` Event Triggered Execution: Application Shimming
Privilege Escalation	`T1546.011` Event Triggered Execution: Application Shimming

Telemetry coverage

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

Rule body

title: Potential Shim Database Persistence via Sdbinst.EXE
id: 517490a7-115a-48c6-8862-1a481504d5a8
related:
    - id: 18ee686c-38a3-4f65-9f44-48a077141f42
      type: similar
status: test
description: |
    Detects installation of a new shim using sdbinst.exe.
    Adversaries may establish persistence and/or elevate privileges by executing malicious content triggered by application shims
references:
    - https://www.mandiant.com/resources/blog/fin7-shim-databases-persistence
author: Markus Neis
date: 2019-01-16
modified: 2023-12-06
tags:
    - attack.persistence
    - attack.privilege-escalation
    - attack.t1546.011
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        - Image|endswith: '\sdbinst.exe'
        - OriginalFileName: 'sdbinst.exe'
    selection_cli:
        CommandLine|contains: '.sdb'
    filter_optional_iis:
        ParentImage|endswith: '\msiexec.exe'
        CommandLine|contains:
            # Expected behavior for IIS Express (e.g. https://www.hybrid-analysis.com/sample/15d4ff941f77f7bdfc9dfb2399b7b952a0a2c860976ef3e835998ff4796e5e91?environmentId=120)
            - ':\Program Files (x86)\IIS Express\iisexpressshim.sdb'
            - ':\Program Files\IIS Express\iisexpressshim.sdb'
    condition: all of selection_* and not 1 of filter_optional_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

all of selection_* and not 1 of filter_optional_*

Stage 1: `selection_img`

selection_img:
    - Image|endswith: '\sdbinst.exe'
    - OriginalFileName: 'sdbinst.exe'

Stage 2: `selection_cli`

selection_cli:
    CommandLine|contains: '.sdb'

Stage 3: `not filter_optional_iis`

filter_optional_iis:
    ParentImage|endswith: '\msiexec.exe'
    CommandLine|contains:
        - ':\Program Files (x86)\IIS Express\iisexpressshim.sdb'
        - ':\Program Files\IIS Express\iisexpressshim.sdb'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`CommandLine`	match	`:\Program Files (x86)\IIS Express\iisexpressshim.sdb`	`excludes:CommandLine` `field:"CommandLine" value:":\Program Files (x86)\IIS Express\iisexpressshim.sdb"`
`CommandLine`	match	`:\Program Files\IIS Express\iisexpressshim.sdb`	`excludes:CommandLine` `field:"CommandLine" value:":\Program Files\IIS Express\iisexpressshim.sdb"`
`ParentImage`	ends_with	`\msiexec.exe`	`excludes:ParentImage` `field:"ParentImage" value:"\msiexec.exe"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	match	`.sdb`	`field:"CommandLine" kind:match value:".sdb"`
`Image`	ends_with	`\sdbinst.exe` corpus 2 (sigma 2)	`field:"Image" kind:ends_with value:"\sdbinst.exe"`
`OriginalFileName`	eq	`sdbinst.exe` corpus 2 (sigma 2)	`field:"OriginalFileName" kind:eq value:"sdbinst.exe"`