FodHelper UAC Bypass
Description
Fodhelper.exe has a known UAC bypass as it attempts to look for specific registry keys upon execution, that do not exist. Therefore, an attacker can write its malicious commands in these registry keys to be executed by fodhelper.exe with the highest privilege. \
-
HKCU:\Software\Classes\ms-settings\shell\open\command
\ -
HKCU:\Software\Classes\ms-settings\shell\open\command\DelegateExecute
\ -
HKCU:\Software\Classes\ms-settings\shell\open\command\(default)
Upon triage, fodhelper.exe will have a child process and read access will occur on the registry keys. Isolate the endpoint and review parallel processes for additional behavior.
- Type: TTP
- Product: Splunk Enterprise, Splunk Enterprise Security, Splunk Cloud
- Datamodel: Endpoint
- Last Updated: 2021-03-01
- Author: Michael Haag, Splunk
- ID: 909f8fd8-7ac8-11eb-a1f3-acde48001122
Annotations
ATT&CK
Kill Chain Phase
- Exploitation
NIST
- DE.CM
CIS20
- CIS 10
CVE
Search
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| tstats `security_content_summariesonly` count min(_time) as firstTime max(_time) as lastTime from datamodel=Endpoint.Processes where Processes.parent_process_name=fodhelper.exe by Processes.dest Processes.user Processes.parent_process Processes.process_name Processes.process Processes.process_id Processes.parent_process_id
| `drop_dm_object_name(Processes)`
| `security_content_ctime(firstTime)`
| `security_content_ctime(lastTime)`
| `fodhelper_uac_bypass_filter`
Macros
The SPL above uses the following Macros:
fodhelper_uac_bypass_filter is a empty macro by default. It allows the user to filter out any results (false positives) without editing the SPL.
Required fields
List of fields required to use this analytic.
- _time
- Processes.parent_process_name
- Processes.dest
- Processes.user
- Processes.parent_process
- Processes.process_name
- Processes.process
- Processes.process_id
- Processes.parent_process_id
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 Processes
node.
Known False Positives
Limited to no false positives are expected.
Associated Analytic Story
RBA
Risk Score | Impact | Confidence | Message |
---|---|---|---|
81.0 | 90 | 90 | Suspcious registy keys added by process fodhelper.exe (process_id- $process_id), with a parent_process of $parent_process_name$ that has been executed on $dest$ by $user$. |
The Risk Score is calculated by the following formula: Risk Score = (Impact * Confidence/100). Initial Confidence and Impact is set by the analytic author.
Reference
- https://blog.malwarebytes.com/malwarebytes-news/2021/02/lazyscripter-from-empire-to-double-rat/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1548.002/T1548.002.md
- https://github.com/gushmazuko/WinBypass/blob/master/FodhelperBypass.ps1
- https://attack.mitre.org/techniques/T1548/002/
Test Dataset
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 | version: 1