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Sigma rules for CVE-2020-2817

8 rules · scoped to cve · back to CVE-2020-2817
Direct rules mention this entity in their title or description. Related rules cover the techniques this entity is known to use.

Detection rules

8 of 8
direct high
Suspicious Scripting in a WMI Consumer
Detects suspicious commands that are related to scripting/powershell in WMI Event Consumers
status test author Florian Roth (Nextron Systems), Jonhnathan Ribeiro id fe21810c-2a8c-478f-8dd3-5a287fb2a0e0 license Sigma · DRL-1.1
view Sigma YAML
title: Suspicious Scripting in a WMI Consumer
id: fe21810c-2a8c-478f-8dd3-5a287fb2a0e0
status: test
description: Detects suspicious commands that are related to scripting/powershell in WMI Event Consumers
references:
    - https://in.security/an-intro-into-abusing-and-identifying-wmi-event-subscriptions-for-persistence/
    - https://github.com/Neo23x0/signature-base/blob/615bf1f6bac3c1bdc417025c40c073e6c2771a76/yara/gen_susp_lnk_files.yar#L19
    - https://github.com/RiccardoAncarani/LiquidSnake
author: Florian Roth (Nextron Systems), Jonhnathan Ribeiro
date: 2019-04-15
modified: 2023-09-09
tags:
    - attack.execution
    - attack.t1059.005
logsource:
    product: windows
    category: wmi_event
detection:
    selection_destination:
        - Destination|contains|all:
              - 'new-object'
              - 'net.webclient'
              - '.downloadstring'
        - Destination|contains|all:
              - 'new-object'
              - 'net.webclient'
              - '.downloadfile'
        - Destination|contains:
              - ' iex('
              - ' -nop '
              - ' -noprofile '
              - ' -decode '
              - ' -enc '
              - 'WScript.Shell'
              - 'System.Security.Cryptography.FromBase64Transform'
    condition: selection_destination
falsepositives:
    - Legitimate administrative scripts
level: high
direct high
Windows Shell/Scripting Application File Write to Suspicious Folder
Detects Windows shells and scripting applications that write files to suspicious folders
status test author Florian Roth (Nextron Systems) id 1277f594-a7d1-4f28-a2d3-73af5cbeab43 license Sigma · DRL-1.1
view Sigma YAML
title: Windows Shell/Scripting Application File Write to Suspicious Folder
id: 1277f594-a7d1-4f28-a2d3-73af5cbeab43
status: test
description: Detects Windows shells and scripting applications that write files to suspicious folders
references:
    - Internal Research
author: Florian Roth (Nextron Systems)
date: 2021-11-20
modified: 2023-03-29
tags:
    - attack.execution
    - attack.t1059
logsource:
    category: file_event
    product: windows
detection:
    selection_1:
        Image|endswith:
            - '\bash.exe'
            - '\cmd.exe'
            - '\cscript.exe'
            - '\msbuild.exe'  # https://github.com/elastic/detection-rules/blob/c76a39796972ecde44cb1da6df47f1b6562c9770/rules/windows/defense_evasion_execution_msbuild_started_by_office_app.toml
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\sh.exe'
            - '\wscript.exe'
        TargetFilename|startswith:
            - 'C:\PerfLogs\'
            - 'C:\Users\Public\'
    selection_2:
        Image|endswith:
            - '\certutil.exe'
            - '\forfiles.exe'
            - '\mshta.exe'
            # - '\rundll32.exe' # Potential FP
            - '\schtasks.exe'
            - '\scriptrunner.exe'
            - '\wmic.exe'  # https://app.any.run/tasks/c903e9c8-0350-440c-8688-3881b556b8e0/
        TargetFilename|contains:
            - 'C:\PerfLogs\'
            - 'C:\Users\Public\'
            - 'C:\Windows\Temp\'
    condition: 1 of selection_*
falsepositives:
    - Unknown
level: high
direct high
Windows Shell/Scripting Processes Spawning Suspicious Programs
Detects suspicious child processes of a Windows shell and scripting processes such as wscript, rundll32, powershell, mshta...etc.
status test author Florian Roth (Nextron Systems), Tim Shelton id 3a6586ad-127a-4d3b-a677-1e6eacdf8fde license Sigma · DRL-1.1
view Sigma YAML
title: Windows Shell/Scripting Processes Spawning Suspicious Programs
id: 3a6586ad-127a-4d3b-a677-1e6eacdf8fde
status: test
description: Detects suspicious child processes of a Windows shell and scripting processes such as wscript, rundll32, powershell, mshta...etc.
references:
    - https://mgreen27.github.io/posts/2018/04/02/DownloadCradle.html
author: Florian Roth (Nextron Systems), Tim Shelton
date: 2018-04-06
modified: 2023-05-23
tags:
    - attack.execution
    - attack.stealth
    - attack.t1059.005
    - attack.t1059.001
    - attack.t1218
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\mshta.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            # - '\cmd.exe'  # too many false positives
            - '\rundll32.exe'
            - '\cscript.exe'
            - '\wscript.exe'
            - '\wmiprvse.exe'
            - '\regsvr32.exe'
        Image|endswith:
            - '\schtasks.exe'
            - '\nslookup.exe'
            - '\certutil.exe'
            - '\bitsadmin.exe'
            - '\mshta.exe'
    filter_ccmcache:
        CurrentDirectory|contains: '\ccmcache\'
    filter_amazon:
        ParentCommandLine|contains:
            # FP - Amazon Workspaces
            - '\Program Files\Amazon\WorkSpacesConfig\Scripts\setup-scheduledtask.ps1'
            - '\Program Files\Amazon\WorkSpacesConfig\Scripts\set-selfhealing.ps1'
            - '\Program Files\Amazon\WorkSpacesConfig\Scripts\check-workspacehealth.ps1'
            - '\nessus_' # Tenable/Nessus VA Scanner
    filter_nessus:
        CommandLine|contains: '\nessus_' # Tenable/Nessus VA Scanner
    filter_sccm_install:
        ParentImage|endswith: '\mshta.exe'
        Image|endswith: '\mshta.exe'
        ParentCommandLine|contains|all:
            - 'C:\MEM_Configmgr_'
            - '\splash.hta'
            - '{1E460BD7-F1C3-4B2E-88BF-4E770A288AF5}'
        CommandLine|contains|all:
            - 'C:\MEM_Configmgr_'
            - '\SMSSETUP\BIN\'
            - '\autorun.hta'
            - '{1E460BD7-F1C3-4B2E-88BF-4E770A288AF5}'
    condition: selection and not 1 of filter_*
falsepositives:
    - Administrative scripts
    - Microsoft SCCM
level: high
direct high
DotNet CLR DLL Loaded By Scripting Applications
Detects .NET CLR DLLs being loaded by scripting applications such as wscript or cscript. This could be an indication of potential suspicious execution.
status test author omkar72, oscd.community id 4508a70e-97ef-4300-b62b-ff27992990ea license Sigma · DRL-1.1
view Sigma YAML
title: DotNet CLR DLL Loaded By Scripting Applications
id: 4508a70e-97ef-4300-b62b-ff27992990ea
status: test
description: Detects .NET CLR DLLs being loaded by scripting applications such as wscript or cscript. This could be an indication of potential suspicious execution.
references:
    - https://github.com/tyranid/DotNetToJScript
    - https://thewover.github.io/Introducing-Donut/
    - https://web.archive.org/web/20230329154538/https://blog.menasec.net/2019/07/interesting-difr-traces-of-net-clr.html
    - https://web.archive.org/web/20221026202428/https://gist.github.com/code-scrap/d7f152ffcdb3e0b02f7f394f5187f008
author: omkar72, oscd.community
date: 2020-10-14
modified: 2023-02-23
tags:
    - attack.execution
    - attack.privilege-escalation
    - attack.stealth
    - attack.t1055
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith:
            - '\cmstp.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\msxsl.exe'
            - '\regsvr32.exe'
            # - '\svchost.exe'
            - '\wmic.exe'
            - '\wscript.exe'
        ImageLoaded|endswith:
            - '\clr.dll'
            - '\mscoree.dll'
            - '\mscorlib.dll'
    condition: selection
falsepositives:
    - Unknown
level: high
direct high
Cross Site Scripting Strings
Detects XSS attempts injected via GET requests in access logs
status test author Saw Win Naung, Nasreddine Bencherchali id 65354b83-a2ea-4ea6-8414-3ab38be0d409 license Sigma · DRL-1.1
view Sigma YAML
title: Cross Site Scripting Strings
id: 65354b83-a2ea-4ea6-8414-3ab38be0d409
status: test
description: Detects XSS attempts injected via GET requests in access logs
references:
    - https://github.com/payloadbox/xss-payload-list
    - https://portswigger.net/web-security/cross-site-scripting/contexts
author: Saw Win Naung, Nasreddine Bencherchali
date: 2021-08-15
modified: 2022-06-14
tags:
    - attack.initial-access
    - attack.t1189
logsource:
    category: webserver
detection:
    select_method:
        cs-method: 'GET'
    keywords:
        - '=<script>'
        - '=%3Cscript%3E'
        - '=%253Cscript%253E'
        - '<iframe '
        - '%3Ciframe '
        - '<svg '
        - '%3Csvg '
        - 'document.cookie'
        - 'document.domain'
        - ' onerror='
        - ' onresize='
        - ' onload="'
        - 'onmouseover='
        - '${alert'
        - 'javascript:alert'
        - 'javascript%3Aalert'
    filter:
        sc-status: 404
    condition: select_method and keywords and not filter
falsepositives:
    - JavaScripts,CSS Files and PNG files
    - User searches in search boxes of the respective website
    - Internal vulnerability scanners can cause some serious FPs when used, if you experience a lot of FPs due to this think of adding more filters such as "User Agent" strings and more response codes
level: high
direct medium
MacOS Scripting Interpreter AppleScript
Detects execution of AppleScript of the macOS scripting language AppleScript.
status test author Alejandro Ortuno, oscd.community id 1bc2e6c5-0885-472b-bed6-be5ea8eace55 license Sigma · DRL-1.1
view Sigma YAML
title: MacOS Scripting Interpreter AppleScript
id: 1bc2e6c5-0885-472b-bed6-be5ea8eace55
status: test
description: Detects execution of AppleScript of the macOS scripting language AppleScript.
references:
    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1059.002/T1059.002.md
    - https://redcanary.com/blog/applescript/
author: Alejandro Ortuno, oscd.community
date: 2020-10-21
modified: 2023-02-01
tags:
    - attack.execution
    - attack.t1059.002
logsource:
    category: process_creation
    product: macos
detection:
    selection:
        Image|endswith: '/osascript'
        CommandLine|contains:
            - ' -e '
            - '.scpt'
            - '.js'
    condition: selection
falsepositives:
    - Application installers might contain scripts as part of the installation process.
level: medium
direct medium
Scripting/CommandLine Process Spawned Regsvr32
Detects various command line and scripting engines/processes such as "PowerShell", "Wscript", "Cmd", etc. spawning a "regsvr32" instance.
status test author Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems) id ab37a6ec-6068-432b-a64e-2c7bf95b1d22 license Sigma · DRL-1.1
view Sigma YAML
title: Scripting/CommandLine Process Spawned Regsvr32
id: ab37a6ec-6068-432b-a64e-2c7bf95b1d22
related:
    - id: 8e2b24c9-4add-46a0-b4bb-0057b4e6187d
      type: obsolete
status: test
description: Detects various command line and scripting engines/processes such as "PowerShell", "Wscript", "Cmd", etc. spawning a "regsvr32" instance.
references:
    - https://web.archive.org/web/20171001085340/https://subt0x10.blogspot.com/2017/04/bypass-application-whitelisting-script.html
    - https://app.any.run/tasks/34221348-072d-4b70-93f3-aa71f6ebecad/
author: Florian Roth (Nextron Systems), Nasreddine Bencherchali (Nextron Systems)
date: 2023-05-26
tags:
    - attack.stealth
    - attack.t1218.010
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith:
            - '\cmd.exe'
            - '\cscript.exe'
            - '\mshta.exe'
            - '\powershell_ise.exe'
            - '\powershell.exe'
            - '\pwsh.exe'
            - '\wscript.exe'
        Image|endswith: '\regsvr32.exe'
    filter_main_rpcproxy:
        ParentImage: C:\Windows\System32\cmd.exe
        CommandLine|endswith: ' /s C:\Windows\System32\RpcProxy\RpcProxy.dll'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Legitimate ".bat", ".hta", ".ps1" or ".vbs" scripts leverage legitimately often. Apply additional filter and exclusions as necessary
    - Some legitimate Windows services
level: medium # Can be reduced to low if you experience a ton of FP
direct medium
WMIC Loading Scripting Libraries
Detects threat actors proxy executing code and bypassing application controls by leveraging wmic and the `/FORMAT` argument switch to download and execute an XSL file (i.e js, vbs, etc). It could be an indicator of SquiblyTwo technique, which uses Windows Management Instrumentation (WMI) to execute malicious code.
status test author Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research) id 06ce37c2-61ab-4f05-9ff5-b1a96d18ae32 license Sigma · DRL-1.1
view Sigma YAML
title: WMIC Loading Scripting Libraries
id: 06ce37c2-61ab-4f05-9ff5-b1a96d18ae32
related:
    - id: 8d63dadf-b91b-4187-87b6-34a1114577ea
      type: similar
    - id: 05c36dd6-79d6-4a9a-97da-3db20298ab2d
      type: similar
status: test
description: |
    Detects threat actors proxy executing code and bypassing application controls by leveraging wmic and the `/FORMAT` argument switch to download and execute an XSL file (i.e js, vbs, etc).
    It could be an indicator of SquiblyTwo technique, which uses Windows Management Instrumentation (WMI) to execute malicious code.
references:
    - https://securitydatasets.com/notebooks/atomic/windows/defense_evasion/SDWIN-201017061100.html
    - https://twitter.com/dez_/status/986614411711442944
    - https://lolbas-project.github.io/lolbas/Binaries/Wmic/
author: Roberto Rodriguez (Cyb3rWard0g), OTR (Open Threat Research)
date: 2020-10-17
modified: 2022-10-13
tags:
    - attack.stealth
    - attack.t1220
logsource:
    category: image_load
    product: windows
detection:
    selection:
        Image|endswith: '\wmic.exe'
        ImageLoaded|endswith:
            - '\jscript.dll'
            - '\vbscript.dll'
    condition: selection
falsepositives:
    - The command wmic os get lastbootuptime loads vbscript.dll
    - The command wmic os get locale loads vbscript.dll
    - Since the ImageLoad event doesn't have enough information in this case. It's better to look at the recent process creation events that spawned the WMIC process and investigate the command line and parent/child processes to get more insights
    - The command `wmic ntevent` loads vbscript.dll
level: medium
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