Potential Persistence Via Event Viewer Events.asp

Hunt Hypothesis

Detects potential registry persistence technique using the Event Viewer “Events.asp” technique

Detection Rule

Sigma (Original)

title: Potential Persistence Via Event Viewer Events.asp
id: a1e11042-a74a-46e6-b07c-c4ce8ecc239b
status: test
description: Detects potential registry persistence technique using the Event Viewer "Events.asp" technique
references:
    - https://twitter.com/nas_bench/status/1626648985824788480
    - https://admx.help/?Category=Windows_7_2008R2&Policy=Microsoft.Policies.InternetCommunicationManagement::EventViewer_DisableLinks
    - https://www.hexacorn.com/blog/2019/02/15/beyond-good-ol-run-key-part-103/
    - https://github.com/redcanaryco/atomic-red-team/blob/f296668303c29d3f4c07e42bdd2b28d8dd6625f9/atomics/T1112/T1112.md
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-02-17
modified: 2023-03-05
tags:
    - attack.persistence
    - attack.defense-impairment
    - attack.t1112
logsource:
    category: registry_set
    product: windows
detection:
    selection:
        # Covers both "\Policies\" and "\Software\" paths for both "Machine" and "User" level configs
        # Also "MicrosoftRedirectionProgramCommandLineParameters" key
        TargetObject|contains:
            - '\Microsoft\Windows NT\CurrentVersion\Event Viewer\MicrosoftRedirectionProgram'
            - '\Microsoft\Windows NT\CurrentVersion\Event Viewer\MicrosoftRedirectionURL'
    filter_default_redirect_program:
        Image|endswith: 'C:\WINDOWS\system32\svchost.exe' # Set via GPO
        TargetObject|endswith: '\Microsoft\Windows NT\CurrentVersion\Event Viewer\MicrosoftRedirectionProgram'
        Details: '%%SystemRoot%%\PCHealth\HelpCtr\Binaries\HelpCtr.exe'
    filter_default_redirect_program_cli:
        Image|endswith: 'C:\WINDOWS\system32\svchost.exe' # Set via GPO
        TargetObject|endswith: '\Microsoft\Windows NT\CurrentVersion\Event Viewer\MicrosoftRedirectionProgramCommandLineParameters'
        Details: '-url hcp://services/centers/support?topic=%%s'
    filter_url:
        Details: 'http://go.microsoft.com/fwlink/events.asp'
    filter_cleaner:
        Details: '(Empty)'
    condition: selection and not 1 of filter_*
falsepositives:
    - Unknown
level: medium

KQL (Azure Sentinel)

imRegistry
| where (RegistryKey contains "\\Microsoft\\Windows NT\\CurrentVersion\\Event Viewer\\MicrosoftRedirectionProgram" or RegistryKey contains "\\Microsoft\\Windows NT\\CurrentVersion\\Event Viewer\\MicrosoftRedirectionURL") and (not(((ActingProcessName endswith "C:\\WINDOWS\\system32\\svchost.exe" and RegistryKey endswith "\\Microsoft\\Windows NT\\CurrentVersion\\Event Viewer\\MicrosoftRedirectionProgram" and RegistryValueData =~ "%%SystemRoot%%\\PCHealth\\HelpCtr\\Binaries\\HelpCtr.exe") or (ActingProcessName endswith "C:\\WINDOWS\\system32\\svchost.exe" and RegistryKey endswith "\\Microsoft\\Windows NT\\CurrentVersion\\Event Viewer\\MicrosoftRedirectionProgramCommandLineParameters" and RegistryValueData matches regex "-url hcp://services/centers/support.topic=%%s") or RegistryValueData =~ "http://go.microsoft.com/fwlink/events.asp" or RegistryValueData =~ "(Empty)")))

Required Data Sources

False Positive Guidance

• Unknown

MITRE ATT&CK Context

• Tactic: Persistence
• Technique: T1112 — T1112

References

• https://twitter.com/nas_bench/status/1626648985824788480
• https://admx.help/?Category=Windows_7_2008R2&Policy=Microsoft.Policies.InternetCommunicationManagement::EventViewer_DisableLinks
• https://www.hexacorn.com/blog/2019/02/15/beyond-good-ol-run-key-part-103/
• https://github.com/redcanaryco/atomic-red-team/blob/f296668303c29d3f4c07e42bdd2b28d8dd6625f9/atomics/T1112/T1112.md
• SigmaHQ Rule