Detection rules › Splunk
Potential fodhelper UAC Bypass Attempt (Windows Event Log)
Adversaries may bypass UAC mechanisms to elevate process privileges on system. Windows User Account Control (UAC) allows a program to elevate its privileges (tracked as integrity levels ranging from low to high) to perform a task under administrator-level permissions, possibly by prompting the user for confirmation. This use case detects the creation of registry keys associated with known methods of using fodhelper to bypass UAC. Atomic Test #3: T1548.002
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Privilege Escalation | T1548.002 Abuse Elevation Control Mechanism: Bypass User Account Control |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Security-Auditing | Event ID 4657 | A registry value was modified. |
| Security-Auditing | Event ID 4688 | A new process has been created. |
Rule body yaml
id: '20217.35898'
title: Potential fodhelper UAC Bypass Attempt
description: 'Adversaries may bypass UAC mechanisms to elevate process privileges
on system. Windows User Account Control (UAC) allows a program to elevate its privileges
(tracked as integrity levels ranging from low to high) to perform a task under administrator-level
permissions, possibly by prompting the user for confirmation. This use case detects
the creation of registry keys associated with known methods of using fodhelper to
bypass UAC. Atomic Test #3: T1548.002'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR
"<EventID>4688<" OR Type=Process OR TERM(EventCode=4657) OR "<EventID>4657<") "\\Software\\Classes\\ms-settings\\shell\\open\\command"
| regex process="(?i)ms-settings\x5cshell\x5copen\x5ccommand.+" | table _time, host,
user, process, process_*, parent_process_* | bin span=1s | stats values(*) as *
by _time, host '
techniques:
- privilege-escalation:abuse elevation control mechanism:bypass user account control
- defense-evasion:abuse elevation control mechanism:bypass user account control
technique_id:
- T1548.002
data_category:
- Process command-line parameters
- Windows event logs
references:
- https://blog.sygnia.co/breaking-down-casbaneiro-infection-chain-part2?_ga=2.66949422.1638613298.1690290265-1923873697.1682517767
- https://gist.github.com/netbiosX/a114f8822eb20b115e33db55deee6692
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_winevent` (TERM(EventCode=4688) OR "<EventID>4688<" OR Type=Process OR TERM(EventCode=4657) OR "<EventID>4657<") "\\Software\\Classes\\ms-settings\\shell\\open\\command"
Stage 2: regex
| regex process="(?i)ms-settings\x5cshell\x5copen\x5ccommand.+"
Stage 3: table
| table _time, host, user, process, process_*, parent_process_*
Stage 4: bucket
| bin span=1s
Stage 5: stats
| stats values(*) as * by _time, host
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.
Search terms
Bare-string tokens in the SPL search body. Splunk matches each token against _raw (the untyped raw event text) anywhere it appears, not against a specific field. These don't surface in the Indicators table because they aren't predicates on a known field.
| Stage | Term |
|---|---|
| 1 | TERM |
| 1 | "<EventID>4688<" |
| 1 | TERM |
| 1 | "<EventID>4657<" |
| 1 | "\\Software\\Classes\\ms-settings\\shell\\open\\command" |