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Description

This analytic will identify suspicious creation of URL shortcut link files. This technique was seen in CHAOS ransomware where it will drop this .url link file in %startup% folder that contains the path of its malicious dropped file to execute upon the reboot of the targeted host. The creation of this file can be created by a normal application or software but it is a good practice to verify this type of file specially the resource it tries to execute which is commonly a website.

  • Type: TTP
  • Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
  • Datamodel: Endpoint
  • Last Updated: 2023-01-12
  • Author: Teoderick Contreras, Splunk
  • ID: 5c7ee6ad-baf4-44fb-b2f0-0cfeddf82dbc

Annotations

ATT&CK

ATT&CK

ID Technique Tactic
T1204.002 Malicious File Execution
T1204 User Execution Execution
Kill Chain Phase
  • Exploitation
NIST
  • DE.CM
CIS20
  • CIS 3
  • CIS 5
  • CIS 16
CVE 


1
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|tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Filesystem where NOT(Filesystem.file_path IN ("*\\Program Files*")) Filesystem.file_name = *.url by Filesystem.file_create_time Filesystem.process_id  Filesystem.file_name Filesystem.user Filesystem.file_path Filesystem.process_guid Filesystem.dest 
| `drop_dm_object_name(Filesystem)` 
| `security_content_ctime(firstTime)` 
| `security_content_ctime(lastTime)` 
| `windows_user_execution_malicious_url_shortcut_file_filter`

Macros

The SPL above uses the following Macros:

:information_source: windows_user_execution_malicious_url_shortcut_file_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
  • Filesystem.file_create_time
  • Filesystem.process_id
  • Filesystem.file_name
  • Filesystem.user
  • Filesystem.file_path
  • Filesystem.process_guid
  • Filesystem.dest

How To Implement

To successfully implement this search you need to be ingesting information on process that include the name of the Filesystem responsible for the changes from your endpoints into the Endpoint datamodel in the Filesystem node.

Known False Positives

Administrators may allow creation of script or exe in this path.

Associated Analytic Story

RBA

Risk Score Impact Confidence Message
64.0 80 80 a process created URL shortcut file in $file_path$ of $dest$

: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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