ID | Technique | Tactic |
---|---|---|
T1105 | Ingress Tool Transfer | Command And Control |
Detection: Windows Curl Download to Suspicious Path
Description
The following analytic detects the use of Windows Curl.exe to download a file to a suspicious location, such as AppData, ProgramData, or Public directories. It leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions that include the -O or --output options. This activity is significant because downloading files to these locations can indicate an attempt to bypass security controls or establish persistence. If confirmed malicious, this behavior could lead to unauthorized code execution, data exfiltration, or further compromise of the system.
Search
1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time)
3as lastTime from datamodel=Endpoint.Processes where
4`process_curl`
5Processes.process IN ("*-O *","*--output*")
6Processes.process IN (
7 "*:\\PerfLogs\\*",
8 "*:\\Windows\\Temp\\*",
9 "*\\AppData\\*",
10 "*\\ProgramData\\*",
11 "*\\Users\\Public\\*",
12 "*%AppData%*",
13 "*%Public%*",
14 "*%Temp%*",
15 "*%tmp%*"
16 )
17by Processes.action Processes.dest Processes.original_file_name Processes.parent_process
18 Processes.parent_process_exec Processes.parent_process_guid Processes.parent_process_id
19 Processes.parent_process_name Processes.parent_process_path Processes.process Processes.process_exec
20 Processes.process_guid Processes.process_hash Processes.process_id Processes.process_integrity_level
21 Processes.process_name Processes.process_path Processes.user Processes.user_id Processes.vendor_product
22
23| `drop_dm_object_name(Processes)`
24
25| `security_content_ctime(firstTime)`
26
27| `security_content_ctime(lastTime)`
28
29| `windows_curl_download_to_suspicious_path_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
Cisco Network Visibility Module Flow Data | 'cisco:nvm:flowdata' |
'not_applicable' |
|
CrowdStrike ProcessRollup2 | N/A | 'crowdstrike:events:sensor' |
'crowdstrike' |
Sysmon EventID 1 | 'XmlWinEventLog' |
'XmlWinEventLog:Microsoft-Windows-Sysmon/Operational' |
|
Windows Event Log Security 4688 | 'XmlWinEventLog' |
'XmlWinEventLog:Security' |
Macros Used
Name | Value |
---|---|
process_curl | (Processes.process_name=curl.exe OR Processes.original_file_name=Curl.exe) |
windows_curl_download_to_suspicious_path_filter | search * |
windows_curl_download_to_suspicious_path_filter
is an empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Annotations
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 |
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
It is possible Administrators or super users will use Curl for legitimate purposes. Filter as needed.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message:
An instance of $parent_process_name$ spawning $process_name$ was identified on endpoint $dest$ by user $user$ to download a file to a suspicious directory.
Risk Object | Risk Object Type | Risk Score | Threat Objects |
---|---|---|---|
user | user | 80 | parent_process_name, process_name |
dest | system | 80 | parent_process_name, process_name |
References
-
https://thedfirreport.com/2021/10/18/icedid-to-xinglocker-ransomware-in-24-hours/
-
https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1105/T1105.md
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: 14