ID | Technique | Tactic |
---|---|---|
T1587.003 | Digital Certificates | Resource Development |
Detection: Windows Certutil Root Certificate Addition
Description
The following analytic detects the use of certutil.exe to add a certificate to the Root certificate store using the "-addstore" flag. In this case, the certificate is loaded from a temporary file path (e.g., %TEMP%) or other uncommon locations (e.g. C:\Users\Public\), which is highly suspicious and uncommon in legitimate administrative activity. This behavior may indicate an adversary is installing a malicious root certificate to intercept HTTPS traffic, impersonate trusted entities, or bypass security controls. The use of flags such as -f (force) and -Enterprise, combined with loading .tmp files from user-writable locations, is consistent with post-exploitation activity seen in credential theft and adversary-in-the-middle (AiTM) attacks. This should be investigated immediately, especially if correlated with unauthorized privilege use or prior certificate modifications. You should monitor when new certificates are added to the root store because this store is what your system uses to decide which websites, apps, and software can be trusted. If an attacker manages to add their own certificate there, they can silently intercept encrypted traffic, impersonate trusted websites, or make malicious programs look safe. This means they could steal sensitive data, bypass security tools, and keep access to your system even after other malware is removed.
Search
1
2| tstats `security_content_summariesonly`
3 count min(_time) as firstTime
4 max(_time) as lastTime
5 values(Processes.process) as process
6from datamodel=Endpoint.Processes where
7`process_certutil`
8Processes.process=*-addstore*
9Processes.process=*root*
10Processes.process IN (
11 "*:\\PerfLogs\\*",
12 "*:\\Windows\\Temp\\*",
13 "*\\AppData\\Local\\Temp\\*",
14 "*\\ProgramData\\*",
15 "*\\Users\\Public\\*",
16 "*%AppData%*",
17 "*%Public%*",
18 "*%Temp%*",
19 "*%tmp%*"
20 )
21by Processes.action Processes.dest Processes.original_file_name
22 Processes.parent_process Processes.parent_process_exec
23 Processes.parent_process_guid Processes.parent_process_id
24 Processes.parent_process_name Processes.parent_process_path
25 Processes.process Processes.process_exec Processes.process_guid
26 Processes.process_hash Processes.process_id Processes.process_integrity_level
27 Processes.process_name Processes.process_path Processes.user
28 Processes.user_id Processes.vendor_product
29
30| `drop_dm_object_name("Processes")`
31
32| `security_content_ctime(firstTime)`
33
34|`security_content_ctime(lastTime)`
35
36| `windows_certutil_root_certificate_addition_filter`
Data Source
Name | Platform | Sourcetype | Source |
---|---|---|---|
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_certutil | (Processes.process_name=certutil.exe OR Processes.original_file_name=CertUtil.exe) |
windows_certutil_root_certificate_addition_filter | search * |
windows_certutil_root_certificate_addition_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
Administrators or third party utilities may use leverage certutil in order to add a root certificate to the store. Filter as needed or restrict to critical assets on the perimeter.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message:
A potentially suspicious certificate was added to the Root certificate store via Certutil on $dest$.
Risk Object | Risk Object Type | Risk Score | Threat Objects |
---|---|---|---|
dest | system | 60 | parent_process_name |
References
-
https://www.deepinstinct.com/blog/iranian-threat-actor-continues-to-develop-mass-exploitation-tools
-
https://unit42.paloaltonetworks.com/retefe-banking-trojan-targets-sweden-switzerland-and-japan/
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: 2