Bypass UAC via WSReset.exe

Status: test
Severity: high
Log source: category process_creation, product windows
Author: E.M. Anhaus (originally from Atomic Blue Detections, Tony Lambert), oscd.community, Florian Roth
Source: github.com/SigmaHQ/sigma

Detects use of WSReset.exe to bypass User Account Control (UAC). Adversaries use this technique to execute privileged processes.

Known false positives

Unknown sub processes of Wsreset.exe

MITRE ATT&CK coverage

Tactic	Techniques
Privilege Escalation	`T1548.002` Abuse Elevation Control Mechanism: Bypass User Account Control

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 1: Process creation

Rule body

title: Bypass UAC via WSReset.exe
id: d797268e-28a9-49a7-b9a8-2f5039011c5c
related:
    - id: bdc8918e-a1d5-49d1-9db7-ea0fd91aa2ae
      type: obsolete
status: test
description: Detects use of WSReset.exe to bypass User Account Control (UAC). Adversaries use this technique to execute privileged processes.
references:
    - https://eqllib.readthedocs.io/en/latest/analytics/532b5ed4-7930-11e9-8f5c-d46d6d62a49e.html
    - https://lolbas-project.github.io/lolbas/Binaries/Wsreset/
    - https://www.activecyber.us/activelabs/windows-uac-bypass
    - https://twitter.com/ReaQta/status/1222548288731217921
author: E.M. Anhaus (originally from Atomic Blue Detections, Tony Lambert), oscd.community, Florian Roth
date: 2019-10-24
modified: 2022-05-13
tags:
    - attack.privilege-escalation
    - attack.t1548.002
logsource:
    category: process_creation
    product: windows
detection:
    selection:
        ParentImage|endswith: '\wsreset.exe'
    filter:
        - Image|endswith: '\conhost.exe'
        - OriginalFileName: 'CONHOST.EXE'
    condition: selection and not filter
falsepositives:
    - Unknown sub processes of Wsreset.exe
level: high

Stages and Predicates

Stage 0: `condition`

selection and not filter

Stage 1: `selection`

selection:
    ParentImage|endswith: '\wsreset.exe'

Stage 2: `not filter`

filter:
    - Image|endswith: '\conhost.exe'
    - OriginalFileName: 'CONHOST.EXE'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`Image`	ends_with	`\conhost.exe`	`excludes:Image` `field:"Image" value:"\conhost.exe"`
`OriginalFileName`	eq	`CONHOST.EXE`	`excludes:OriginalFileName` `field:"OriginalFileName" value:"CONHOST.EXE"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`ParentImage`	ends_with	`\wsreset.exe`	`field:"ParentImage" kind:ends_with value:"\wsreset.exe"`