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P4T12ICK
67 lines
2.4 KiB
YAML
67 lines
2.4 KiB
YAML
name: Spoolsv Writing a DLL
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id: d5bf5cf2-da71-11eb-92c2-acde48001122
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version: 1
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date: '2021-07-01'
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author: Mauricio Velazco, Michael Haag, Splunk
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status: production
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type: TTP
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description: The following analytic identifies a `.dll` being written by `spoolsv.exe`.
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This was identified during our testing of CVE-2021-34527 previously (CVE-2021-1675)
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or PrintNightmare. Typically, this is not normal behavior for `spoolsv.exe` to write
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a `.dll`. Current POC code used will write the suspicious DLL to disk within a path
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of `\spool\drivers\x64\`. During triage, isolate the endpoint and review for source
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of exploitation. Capture any additional file modification events.
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data_source:
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- Sysmon Event ID 1
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search:
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selection1:
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Image|endswith: spoolsv.exe
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condition: selection1
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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 and `Filesystem`
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node.
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known_false_positives: Unknown.
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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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asset_type: Endpoint
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confidence: 90
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cve:
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- CVE-2021-34527
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impact: 80
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message: $process_name$ has been identified writing dll's to $file_path$ on endpoint
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$dest$. 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: process_id
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type: Process
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role:
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- Child Process
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- name: file_path
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type: File
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role:
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- Other
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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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risk_score: 72
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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/T1547.012/printnightmare/windows-sysmon.log
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source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
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sourcetype: xmlwineventlog
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