HackTool - WSASS Execution

Status: experimental
Severity: high
Log source: category process_creation, product windows
Author: Swachchhanda Shrawan Poudel (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects execution of WSASS, a tool used to dump LSASS memory on Windows systems by leveraging WER's (Windows Error Reporting) WerFaultSecure.EXE to bypass PPL (Protected Process Light) protections.

Known false positives

Unlikely

MITRE ATT&CK coverage

Tactic	Techniques
Credential Access	`T1003.001` OS Credential Dumping: LSASS Memory

Telemetry coverage

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

Rule body

title: HackTool - WSASS Execution
id: 589ac73f-8e12-409c-964e-31a2f5775ae2
status: experimental
description: |
    Detects execution of WSASS, a tool used to dump LSASS memory on Windows systems by leveraging WER's
    (Windows Error Reporting) WerFaultSecure.EXE to bypass PPL (Protected Process Light) protections.
references:
    - https://github.com/TwoSevenOneT/WSASS
    - https://www.zerosalarium.com/2025/09/Dumping-LSASS-With-WER-On-Modern-Windows-11.html
author: Swachchhanda Shrawan Poudel (Nextron Systems)
date: 2025-11-23
modified: 2026-01-09
tags:
    - attack.credential-access
    - attack.t1003.001
logsource:
    category: process_creation
    product: windows
detection:
    selection_img:
        Image|endswith: '\wsass.exe'
    selection_hash:
        Hashes|contains: 'IMPHASH=32F5095C9BBDCACF28FD4060EB4DFC42'
    selection_cli:
        # change to |re|i after Sigma v2.0 release
        # plain string without quotation marks as it has to match for both ' and "
        CommandLine|re: (?i)\.exe[\"\']?\s+[^\"]{0,64}werfaultsecure\.exe[\"\']?\s+\d{2,10} # wsass.exe "path to werfaultsecure" lsass_pid
    condition: 1 of selection_*
falsepositives:
    - Unlikely
level: high
regression_tests_path: regression_data/rules/windows/process_creation/proc_creation_win_hktl_wsass/info.yml

Stages and Predicates

Stage 0: `condition`

1 of selection_*

Stage 1: `selection_img`

selection_img:
    Image|endswith: '\wsass.exe'

Stage 2: `selection_hash`

selection_hash:
    Hashes|contains: 'IMPHASH=32F5095C9BBDCACF28FD4060EB4DFC42'

Stage 3: `selection_cli`

selection_cli:
    CommandLine|re: (?i)\.exe[\"\']?\s+[^\"]{0,64}werfaultsecure\.exe[\"\']?\s+\d{2,10}

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`CommandLine`	regex_match	`(?i).exe[\"\']?\s+[^\"]{0,64}werfaultsecure.exe[\"\']?\s+\d{2,10}`	`field:"CommandLine" kind:regex_match`
`Hashes`	match	`IMPHASH=32F5095C9BBDCACF28FD4060EB4DFC42`	`field:"Hashes" kind:match value:"IMPHASH=32F5095C9BBDCACF28FD4060EB4DFC42"`
`Image`	ends_with	`\wsass.exe`	`field:"Image" kind:ends_with value:"\wsass.exe"`