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
Kill Chain Phase
- CIS 10
1 2 3 4 5 6 | 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`
The SPL above uses the following Macros:
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.
List of fields required to use this analytic.
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
|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 $dest$|
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
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