Detection: File Download or Read to Pipe Execution

Updated Date: 2025-10-16 ID: 26f86252-1549-45e1-a212-eb26840e86bc Author: Michael Haag, Nasreddine Bencherchali, Splunk, DipsyTipsy Type: TTP Product: Splunk Enterprise Security

Description

The following analytic detects the use of download or file reading utilities from Windows, Linux or MacOS to download or read the contents of a file from a remote or local source and pipe it directly to a shell for execution. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions. This activity is significant as it is commonly associated with malicious actions like coinminers and exploits such as CVE-2021-44228 in Log4j. If confirmed malicious, this behavior could allow attackers to execute arbitrary code, potentially leading to system compromise and unauthorized access to sensitive data.

Search

 1
 2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
 3as lastTime
 4
 5from datamodel=Endpoint.Processes where
 6
 7``` This aims to cover download utilities and file reading ones ```
 8
 9Processes.process IN (
10  "*.DownloadFile(*",
11  "*.DownloadString(*",
12  "*ASCII.GetString*",
13  "*bitsadmin*",
14  "*certutil*",
15  "*curl*",
16  "*Invoke-RestMethod*",
17  "*Invoke-WebRequest*",
18  "*irm*",
19  "*iwr *",
20  "*mshta*",
21  "*wget*"
22)
23
24Processes.process IN ("*
25|*")
26
27(
28  ``` Linux / MacOS ```
29  Processes.process IN (
30    "*bash*",
31    "*csh*",
32    "*dash*",
33    "*fish*",
34    "*ksh*",
35    "*rbash*",
36    "*tcsh*",
37    "*zsh*"
38  )
39  OR
40  ``` Because the "sh" string can overlap and is a short atom we treat it in a special case ```
41  Processes.process IN (
42    "*
43|sh"
44    "* sh*"
45  )
46  OR
47  ``` Windows ```
48  Processes.process IN ("*IEX*", "*Invoke-Expression*")
49)
50
51by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
52   Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
53   Processes.parent_process_name Processes.parent_process_path Processes.process
54   Processes.process_exec Processes.process_guid Processes.process_hash Processes.process_id
55   Processes.process_integrity_level Processes.process_name Processes.process_path Processes.user
56   Processes.user_id Processes.vendor_product
57
58
59| `drop_dm_object_name(Processes)`
60
61| `security_content_ctime(firstTime)`
62
63| `security_content_ctime(lastTime)`
64
65| `file_download_or_read_to_pipe_execution_filter`

Data Source

Name	Platform	Sourcetype	Source
CrowdStrike ProcessRollup2	N/A	`'crowdstrike:events:sensor'`	`'crowdstrike'`
Sysmon EventID 1	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational'`
Sysmon for Linux EventID 1	Linux	`'sysmon:linux'`	`'Syslog:Linux-Sysmon/Operational'`
Windows Event Log Security 4688	Windows	`'XmlWinEventLog'`	`'XmlWinEventLog:Security'`

Macros Used

Name	Value
security_content_ctime	`convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$)`
file_download_or_read_to_pipe_execution_filter	`search *`

file_download_or_read_to_pipe_execution_filter is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.

Annotations

- MITRE ATT&CK

+ Kill Chain Phases

+ NIST

+ CIS

- Threat Actors

ID	Technique	Tactic
T1105	Ingress Tool Transfer	Command And Control

Command and Control

DE.CM

CIS 10

Default Configuration

This detection is configured by default in Splunk Enterprise Security to run with the following settings:

Setting	Value
Disabled	true
Cron Schedule	`0 * * * *`
Earliest Time	`-70m@m`
Latest Time	`-10m@m`
Schedule Window	`auto`
Creates Notable	Yes
Rule Title	`%name%`
Rule Description	`%description%`
Notable Event Fields	user, dest
Creates Risk Event	True

This configuration file applies to all detections of type TTP. These detections will use Risk Based Alerting and generate Notable Events.

Implementation

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 should be limited, however filtering may be required.

Associated Analytic Story

Risk Based Analytics (RBA)

Risk Message:

An instance of $process_name$ was identified on endpoint $dest$ attempting to immediately read or download a file and run it via a shell.

Risk Object	Risk Object Type	Risk Score	Threat Objects
user	user	80	process, process_name
dest	system	80	process, process_name

References

Detection Testing

Test Type	Status	Dataset	Source	Sourcetype
Validation	✅ Passing	N/A	N/A	N/A
Unit	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`
Integration	✅ Passing	Dataset	`XmlWinEventLog:Microsoft-Windows-Sysmon/Operational`	`XmlWinEventLog`

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

Source: GitHub | Version: 1