Detection rules › Splunk
Full Control Permissions Granted to Everyone - Windows (Sysmon)
Adversaries may modify file or directory permissions/attributes to evade access control lists and access protected files. Windows implements file and directory ACLs as Discretionary Access Control Lists (DACLs). Adversaries can interact with the DACLs using built-in Windows commands which can grant adversaries higher permissions on specific files and folders. This use case detects commands assigning full control to Everyone which has been observed with Ryuk ransomware
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Defense Impairment | T1222.001 File and Directory Permissions Modification: Windows Permissions |
References
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 1 | Process creation |
Rule body yaml
id: '17741.29790'
title: Full Control Permissions Granted to Everyone - Windows
description: 'Adversaries may modify file or directory permissions/attributes to evade
access control lists and access protected files. Windows implements file and directory
ACLs as Discretionary Access Control Lists (DACLs). Adversaries can interact with
the DACLs using built-in Windows commands which can grant adversaries higher permissions
on specific files and folders. This use case detects commands assigning full control
to Everyone which has been observed with Ryuk ransomware. -- Threat Actor Association:
UNC5812 -- Atomics T1222.001 Test #2 Atomics T1222.001 Test #5'
logic_format: Splunk
logic: '`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<")
TERM(icacls) OR ("/grant" "Everyone:F") | regex process="(?i)\s+\/grant\s+everyone"
| table _time, host, user parent_*, process, process_* | bin span=1s | stats values(*)
as * by _time, host '
techniques:
- defense-evasion:file and directory permissions modification:windows file and directory
permissions modification
technique_id:
- T1222.001
data_category:
- Windows Sysmon
- Process command-line parameters
references:
- https://www.logpoint.com/en/blog/ryuk-ransomware/
- https://github.com/redcanaryco/atomic-red-team/blob/master/atomics/T1222.001/T1222.001.md
Stages and Predicates
Stage 1: search
`get_endpoint_data` `get_endpoint_data_sysmon` (TERM(EventCode=1) OR "<EventID>1<") TERM(icacls) OR ("/grant" "Everyone:F")
Stage 2: regex
| regex process="(?i)\s+\/grant\s+everyone"
Stage 3: table
| table _time, host, user parent_*, process, 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>1<" |
| 1 | TERM |
| 1 | icacls |
| 1 | "/grant" |
| 1 | "Everyone:F" |