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pyth0n1c
89 lines
3.4 KiB
YAML
89 lines
3.4 KiB
YAML
name: Spoolsv Spawning Rundll32
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id: 15d905f6-da6b-11eb-ab82-acde48001122
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version: 2
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date: '2021-07-01'
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author: Mauricio Velazco, Michael Haag, Splunk
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type: TTP
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datamodel:
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- Endpoint
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description: The following analytic identifies a suspicious child process, `rundll32.exe`,
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with no command-line arguments being spawned from `spoolsv.exe`. This was identified
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during our testing of CVE-2021-34527 previously (CVE-2021-1675) or PrintNightmare.
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Typically, this is not normal behavior for `spoolsv.exe` to spawn a process. During
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triage, isolate the endpoint and review for source of exploitation. Capture any
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additional file modification events.
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search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
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as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=spoolsv.exe
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`process_rundll32` by Processes.dest Processes.user Processes.parent_process Processes.original_file_name
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Processes.process_name Processes.process Processes.process_id Processes.parent_process_id
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| `drop_dm_object_name(Processes)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`
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| `spoolsv_spawning_rundll32_filter`'
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how_to_implement: To successfully implement this search you need to be ingesting information
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on process that include the name of the process responsible for the changes from
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your endpoints into the `Endpoint` datamodel in the `Processes` node. In addition,
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confirm the latest CIM App 4.20 or higher is installed and the latest TA for the
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endpoint product.
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known_false_positives: Limited false positives have been identified. There are limited
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instances where `rundll32.exe` may be spawned by a legitimate print driver.
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references:
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- https://www.truesec.com/hub/blog/fix-for-printnightmare-cve-2021-1675-exploit-to-keep-your-print-servers-running-while-a-patch-is-not-available
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- https://www.truesec.com/hub/blog/exploitable-critical-rce-vulnerability-allows-regular-users-to-fully-compromise-active-directory-printnightmare-cve-2021-1675
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- https://www.reddit.com/r/msp/comments/ob6y02/critical_vulnerability_printnightmare_exposes
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tags:
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analytic_story:
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- PrintNightmare CVE-2021-34527
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confidence: 90
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context:
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- Source:Endpoint
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- Stage:Privilege Escalation
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- Stage:Defense Evasion
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- Scope:Local
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cve:
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- CVE-2021-34527
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dataset:
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- https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1547.012/printnightmare/windows-sysmon.log
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impact: 80
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kill_chain_phases:
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- Exploitation
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message: $parent_process$ has spawned $process_name$ on endpoint $ComputerName$.
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This behavior is suspicious and related to PrintNightmare.
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mitre_attack_id:
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- T1547.012
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- T1547
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observable:
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- name: dest
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type: Endpoint
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role:
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- Victim
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- name: parent_process_id
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type: Process
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role:
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- Parent Process
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- Attacker
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- name: process_id
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type: Process
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role:
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- Child Process
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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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required_fields:
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- _time
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- Processes.dest
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- Processes.user
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- Processes.parent_process_name
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- Processes.parent_process
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- Processes.original_file_name
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- Processes.process_name
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- Processes.process
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- Processes.process_id
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- Processes.parent_process_path
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- Processes.process_path
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- Processes.parent_process_id
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risk_score: 72
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security_domain: endpoint
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supported_tas:
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- Splunk_TA_microsoft_sysmon
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asset_type: Endpoint
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