Windows MSI Rollback Script Deleted By Non-Msiexec Process

SPLUNK detection rule by Raven Tait, Splunk · Apache-2.0

Detects deletion of a Rollback Script (.rbs) file under C:\Config.Msi, the critical filesystem manipulation step in an MSI Rollback privilege escalation attack that converts an arbitrary file delete primitive into full SYSTEM code execution. During a legitimate MSI installation, the Windows Installer service (running as SYSTEM) creates C:\Config.Msi and populates it with a Rollback Script (.rbs) and Rollback File (.rbf). These files define exactly how to restore the system to its pre-installation state if the install fails. The folder is protected with a strong DACL specifically to prevent tampering by low-privileged users — because whatever is in these files will be executed by the SYSTEM-level Installer service during rollback.

name: Windows MSI Rollback Script Deleted By Non-Msiexec Process
id: 6ec7cbda-9547-4f6b-8a00-d1fb4b52c1e9
version: 3
creation_date: '2026-05-05'
modification_date: '2026-07-20'
author: Raven Tait, Splunk
status: production
type: TTP
description: |-
    Detects deletion of a Rollback Script (.rbs) file under C:\Config.Msi, the critical filesystem manipulation step in an MSI Rollback privilege escalation attack that converts an arbitrary file delete primitive into full SYSTEM code execution.
    During a legitimate MSI installation, the Windows Installer service (running as SYSTEM) creates C:\Config.Msi and populates it with a Rollback Script (.rbs) and Rollback File (.rbf).
    These files define exactly how to restore the system to its pre-installation state if the install fails.
    The folder is protected with a strong DACL specifically to prevent tampering by low-privileged users — because whatever is in these files will be executed by the SYSTEM-level Installer service during rollback.
data_source:
    - Sysmon EventID 23
    - Sysmon EventID 26
search: |-
    `sysmon`
    EventCode IN (23, 26)
    TargetFilename="*:\\Config.Msi\\*"
    TargetFilename="*.rbs"
    NOT ProcessName="msiexec.exe"
    | fillnull
    | stats count min(_time) as firstTime
                  max(_time) as lastTime
      by Computer ProcessName TargetFilename EventID action dest dvc file_path file_hash
         file_name file_modify_time process_exec process_guid process_id process_name
         process_path signature signature_id user user_id vendor_product

    | `security_content_ctime(firstTime)`
    | `security_content_ctime(lastTime)`
    | `windows_msi_rollback_script_deleted_by_non_msiexec_process_filter`
how_to_implement: The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint` data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.
known_false_positives: Some legitimate system cleanup or MSI uninstallation processes may delete rbs files under c:\Config.Msi. Verify events with approved maintenance activities to reduce false alarms.
references:
    - https://github.com/mbog14/CVE-2024-44193
drilldown_searches:
    - earliest_offset: $info_min_time$
      latest_offset: $info_max_time$
      name: View the detection results for - "$user$" and "$dest$"
      search: '%original_detection_search% | search  user = "$user$" dest = "$dest$"'
    - name: View risk events for the last 7 days for - "$user$" and "$dest$"
      search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$user$", "$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
      earliest_offset: 7d
      latest_offset: "0"
finding:
    title: MSI rollback script file $TargetFilename$ was deleted on $dest$ by $ProcessName$.
    entity:
        field: dest
        type: system
        score: 50
threat_objects:
    - field: TargetFilename
      type: file_path
analytic_story:
    - Windows Privilege Escalation
asset_type: Endpoint
mitre_attack_id:
    - T1218.007
    - T1068
product:
    - Splunk Enterprise
    - Splunk Enterprise Security
    - Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
    - name: True Positive Test
      attack_data:
        - data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1218.007/snapattack/snapattack.log
          source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
          sourcetype: XmlWinEventLog
      test_type: unit

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

6dd1b4cc-af4f-4f17-a604-339e2deba51a

Propose edits, view related rules, and engage with the community through comments.

Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

[[ reason ]]

What does this mean?

Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

[[ reason ]]

What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

Community Discussion