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Description

This analytic is developed to detect suspicious pdf viewer processes that have a browser application child processes. This event was seen in a pdf spear phishing attachment containing a malicious URL link to download the actual payload. When a user clicks the malicious link the pdf viewer application will execute a process of the host default browser to connect to the malicious site. This anomaly detection can be a good indicator that a possible pdf file has a link executed by a user. The pdf viewer and browser list in this detection is still in progress, add the common browser and pdf viewer you use in opening pdf in your network.

  • Type: Anomaly
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2023-01-18
  • Author: Teoderick Contreras, Splunk
  • ID: 2fa9dec8-9d8e-46d3-96c1-202c06f0e6e1

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1566.001 Spearphishing Attachment Initial Access
T1566 Phishing Initial Access
Kill Chain Phase
  • Delivery
NIST
  • DE.AE
CIS20
  • CIS 10
CVE 


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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name  IN ("AcroRd32.exe", "FoxitPDFReader.exe") Processes.process_name IN ("firefox.exe", "chrome.exe", "iexplore.exe") by Processes.user Processes.parent_process_name Processes.process_name  Processes.parent_process Processes.process Processes.process_id Processes.dest 
|`drop_dm_object_name(Processes)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_phishing_pdf_file_executes_url_link_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_phishing_pdf_file_executes_url_link_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Required fields

List of fields required to use this analytic.

  • _time
  • Processes.dest
  • Processes.user
  • Processes.parent_process_name
  • Processes.parent_process
  • Processes.original_file_name
  • Processes.process_name
  • Processes.process
  • Processes.process_id
  • Processes.parent_process_path
  • Processes.process_path
  • Processes.parent_process_id

How To Implement

The detection is based on data that originates from Endpoint Detection and Response (EDR) agents. These agents are designed to provide security-related telemetry from the endpoints where the agent is installed. To implement this search, you must ingest logs that contain the process GUID, process name, and parent process. Additionally, you must ingest complete command-line executions. These logs must be processed using the appropriate Splunk Technology Add-ons that are specific to the EDR product. The logs must also be mapped to the Processes node of the Endpoint data model. Use the Splunk Common Information Model (CIM) to normalize the field names and speed up the data modeling process.

Known False Positives

False positives in PDF file opened PDF Viewer having legitimate URL link, however filter as needed.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 a pdf file opened in pdf viewer process $parent_process_name$ has a child process of a browser $process_name$ in $dest$

:information_source: The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.

Reference

Test Dataset

Replay any dataset to Splunk Enterprise by using our replay.py tool or the UI. Alternatively you can replay a dataset into a Splunk Attack Range

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