ID | Technique | Tactic |
---|---|---|
T1548 | Abuse Elevation Control Mechanism | Defense Evasion |
T1548.002 | Bypass User Account Control | Privilege Escalation |
Detection: Windows UAC Bypass Suspicious Child Process
Description
The following analytic detects when an executable known for User Account Control (UAC) bypass exploitation spawns a child process in a user-controlled location or a command shell executable (e.g., cmd.exe, powershell.exe). This detection leverages Sysmon EventID 1 data, focusing on high or system integrity level processes with specific parent-child process relationships. This activity is significant as it may indicate an attacker has successfully used a UAC bypass exploit to escalate privileges. If confirmed malicious, this could allow the attacker to execute arbitrary commands with elevated privileges, potentially compromising the entire system.
Search
1
2| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.process_integrity_level IN ("high","system") AND Processes.parent_process_name IN (`uacbypass_process_name`) AND (Processes.process_name IN ("cmd.exe","powershell.exe","pwsh.exe","wscript","cscript.exe","bash.exe","werfault.exe") OR Processes.process IN ("*\\\\*","*\\Users\\*","*\\ProgramData\\*","*\\Temp\\*")) by Processes.dest, Processes.user, Processes.parent_process_guid, Processes.parent_process, Processes.parent_process_name Processes.process_name Processes.process, Processes.process_path, Processes.process_integrity_level, Processes.process_current_directory
3| `drop_dm_object_name(Processes)`
4| where parent_process_name != process_name
5| `security_content_ctime(firstTime)`
6| `security_content_ctime(lastTime)`
7| `windows_uac_bypass_suspicious_child_process_filter`
Data Source
Name | Platform | Sourcetype | Source | Supported App |
---|---|---|---|---|
CrowdStrike ProcessRollup2 | N/A | 'crowdstrike:events:sensor' |
'crowdstrike' |
N/A |
Macros Used
Name | Value |
---|---|
security_content_ctime | convert timeformat="%Y-%m-%dT%H:%M:%S" ctime($field$) |
windows_uac_bypass_suspicious_child_process_filter | search * |
windows_uac_bypass_suspicious_child_process_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
Target environment must ingest sysmon data, specifically Event ID 1 with process integrity level data.
Known False Positives
Including Werfault.exe may cause some unintended false positives related to normal application faulting, but is used in a number of UAC bypass techniques.
Associated Analytic Story
Risk Based Analytics (RBA)
Risk Message | Risk Score | Impact | Confidence |
---|---|---|---|
A UAC bypass parent process- $parent_process_name$ on host- $dest$ launched a suspicious child process - $process_name$. | 45 | 60 | 75 |
References
-
https://hadess.io/user-account-control-uncontrol-mastering-the-art-of-bypassing-windows-uac/
-
https://enigma0x3.net/2016/08/15/fileless-uac-bypass-using-eventvwr-exe-and-registry-hijacking/
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