Detection rules › Splunk
NET Profiler UAC bypass
The following analytic detects modifications to the registry aimed at bypassing the User Account Control (UAC) feature in Windows. It identifies changes to the .NET COR_PROFILER_PATH registry key, which can be exploited to load a malicious DLL via mmc.exe. This detection leverages data from the Endpoint.Registry datamodel, focusing on specific registry paths and values. Monitoring this activity is crucial as it can indicate an attempt to escalate privileges or persist within the environment. If confirmed malicious, this could allow an attacker to execute arbitrary code with elevated privileges, compromising system integrity.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Privilege Escalation | T1548.002 Abuse Elevation Control Mechanism: Bypass User Account Control |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 13 | RegistryEvent (Value Set) |
Rule body splunk
name: NET Profiler UAC bypass
id: 0252ca80-e30d-11eb-8aa3-acde48001122
version: 11
creation_date: '2021-07-08'
modification_date: '2026-05-13'
author: Teoderick Contreras, Splunk
status: production
type: TTP
description: The following analytic detects modifications to the registry aimed at bypassing the User Account Control (UAC) feature in Windows. It identifies changes to the .NET COR_PROFILER_PATH registry key, which can be exploited to load a malicious DLL via mmc.exe. This detection leverages data from the Endpoint.Registry datamodel, focusing on specific registry paths and values. Monitoring this activity is crucial as it can indicate an attempt to escalate privileges or persist within the environment. If confirmed malicious, this could allow an attacker to execute arbitrary code with elevated privileges, compromising system integrity.
data_source:
- Sysmon EventID 13
search: '| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path= "*\\Environment\\COR_PROFILER_PATH" Registry.registry_value_data = "*.dll" by Registry.action Registry.dest Registry.process_guid Registry.process_id Registry.registry_hive Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name Registry.registry_value_type Registry.status Registry.user Registry.vendor_product | `drop_dm_object_name(Registry)` | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)` | `net_profiler_uac_bypass_filter`'
how_to_implement: To successfully implement this search you need to be ingesting information on process that include the name of the process responsible for the changes from your endpoints into the `Endpoint` datamodel in the `Registry` node. Also make sure that this registry was included in your config files ex. sysmon config to be monitored.
known_false_positives: limited false positive. It may trigger by some windows update that will modify this registry.
references:
- https://offsec.almond.consulting/UAC-bypass-dotnet.html
drilldown_searches:
- name: View the detection results for - "$dest$"
search: '%original_detection_search% | search dest = "$dest$"'
earliest_offset: $info_min_time$
latest_offset: $info_max_time$
- name: View risk events for the last 7 days for - "$dest$"
search: '| from datamodel Risk.All_Risk | search normalized_risk_object IN ("$dest$") | stats count min(_time) as firstTime max(_time) as lastTime values(search_name) as "Search Name" values(risk_message) as "Risk Message" values(analyticstories) as "Analytic Stories" values(annotations._all) as "Annotations" values(annotations.mitre_attack.mitre_tactic) as "ATT&CK Tactics" by normalized_risk_object | `security_content_ctime(firstTime)` | `security_content_ctime(lastTime)`'
earliest_offset: 7d
latest_offset: "0"
finding:
title: Suspicious modification of registry $registry_path$ with possible payload path $registry_path$ and key $registry_key_name$ on $dest$
entity:
field: dest
type: system
score: 50
analytic_story:
- Windows Defense Evasion Tactics
asset_type: Endpoint
mitre_attack_id:
- T1548.002
product:
- Splunk Enterprise
- Splunk Enterprise Security
- Splunk Cloud
category: endpoint
security_domain: endpoint
tests:
- name: True Positive Test
attack_data:
- data: https://media.githubusercontent.com/media/splunk/attack_data/master/datasets/attack_techniques/T1548/uac_bypass/windows-sysmon2.log
source: XmlWinEventLog:Microsoft-Windows-Sysmon/Operational
sourcetype: XmlWinEventLog
test_type: unit
Stages and Predicates
Stage 1: tstats
| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Registry where Registry.registry_path= "*\\Environment\\COR_PROFILER_PATH" Registry.registry_value_data = "*.dll" by Registry.action Registry.dest Registry.process_guid Registry.process_id Registry.registry_hive Registry.registry_path Registry.registry_key_name Registry.registry_value_data Registry.registry_value_name Registry.registry_value_type Registry.status Registry.user Registry.vendor_product
Stage 2: search
| `drop_dm_object_name(Registry)`
Stage 3: search
| `security_content_ctime(firstTime)`
Stage 4: search
| `security_content_ctime(lastTime)`
Stage 5: search
| `net_profiler_uac_bypass_filter`
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
Registry.registry_path | eq |
|
Registry.registry_value_data | eq |
|