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https://github.com/splunk/security_content
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Michael Haag
102 lines
5.0 KiB
YAML
102 lines
5.0 KiB
YAML
name: W3WP Spawning Shell
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id: 0f03423c-7c6a-11eb-bc47-acde48001122
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version: 10
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date: '2025-09-16'
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author: Michael Haag, Splunk
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status: production
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type: TTP
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description: The following analytic identifies instances where a shell (PowerShell.exe
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or Cmd.exe) is spawned from W3WP.exe, the IIS worker process. This detection leverages
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data from Endpoint Detection and Response (EDR) agents, focusing on process creation
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events where the parent process is W3WP.exe. This activity is significant as it
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may indicate webshell activity, often associated with exploitation attempts like
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those by the HAFNIUM Group on Exchange servers. If confirmed malicious, this behavior
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could allow attackers to execute arbitrary commands, potentially leading to system
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compromise, data exfiltration, or further lateral movement within the network.
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data_source:
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- Sysmon EventID 1
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- Windows Event Log Security 4688
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- CrowdStrike ProcessRollup2
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search: '| tstats `security_content_summariesonly` count values(Processes.process_name)
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as process_name values(Processes.process) as process min(_time) as firstTime max(_time)
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as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=w3wp.exe
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AND `process_cmd` OR `process_powershell` by Processes.action Processes.dest Processes.original_file_name
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Processes.parent_process Processes.parent_process_exec Processes.parent_process_guid
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Processes.parent_process_id Processes.parent_process_name Processes.parent_process_path
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Processes.process Processes.process_exec Processes.process_guid Processes.process_hash
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Processes.process_id Processes.process_integrity_level Processes.process_name Processes.process_path
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Processes.user Processes.user_id Processes.vendor_product | `drop_dm_object_name(Processes)`
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| `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`| `w3wp_spawning_shell_filter`'
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how_to_implement: The detection is based on data that originates from Endpoint Detection
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and Response (EDR) agents. These agents are designed to provide security-related
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telemetry from the endpoints where the agent is installed. To implement this search,
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you must ingest logs that contain the process GUID, process name, and parent process.
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Additionally, you must ingest complete command-line executions. These logs must
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be processed using the appropriate Splunk Technology Add-ons that are specific to
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the EDR product. The logs must also be mapped to the `Processes` node of the `Endpoint`
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data model. Use the Splunk Common Information Model (CIM) to normalize the field
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names and speed up the data modeling process.
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known_false_positives: Baseline your environment before production. It is possible
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build systems using IIS will spawn cmd.exe to perform a software build. Filter as
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needed.
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references:
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- https://www.microsoft.com/security/blog/2020/02/04/ghost-in-the-shell-investigating-web-shell-attacks/
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- https://www.zerodayinitiative.com/blog/2021/8/17/from-pwn2own-2021-a-new-attack-surface-on-microsoft-exchange-proxyshell
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- https://www.youtube.com/watch?v=FC6iHw258RI
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- https://www.huntress.com/blog/rapid-response-microsoft-exchange-servers-still-vulnerable-to-proxyshell-exploit#what-should-you-do
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drilldown_searches:
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- name: View the detection results for - "$dest$"
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search: '%original_detection_search% | search dest = "$dest$"'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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- name: View risk events for the last 7 days for - "$dest$"
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search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$")
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starthoursago=168 | stats count min(_time) as firstTime max(_time) as lastTime
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values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories)
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as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic)
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as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)`
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| `security_content_ctime(lastTime)`'
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earliest_offset: $info_min_time$
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latest_offset: $info_max_time$
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rba:
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message: Possible Web Shell execution on $dest$
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risk_objects:
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- field: dest
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type: system
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score: 56
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threat_objects: []
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tags:
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analytic_story:
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- ProxyNotShell
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- Data Destruction
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- ProxyShell
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- Hermetic Wiper
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- CISA AA22-257A
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- HAFNIUM Group
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- BlackByte Ransomware
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- CISA AA22-264A
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- Flax Typhoon
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- WS FTP Server Critical Vulnerabilities
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- PHP-CGI RCE Attack on Japanese Organizations
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- Microsoft SharePoint Vulnerabilities
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- GhostRedirector IIS Module and Rungan Backdoor
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asset_type: Endpoint
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cve:
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- CVE-2021-34473
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- CVE-2021-34523
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- CVE-2021-31207
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- CVE-2025-53770
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mitre_attack_id:
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- T1505.003
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product:
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- Splunk Enterprise
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- Splunk Enterprise Security
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- Splunk Cloud
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security_domain: endpoint
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tests:
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- name: True Positive Test
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attack_data:
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- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1505.003/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: XmlWinEventLog
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