Potential CVE-2023-36874 Exploitation - Uncommon Report.Wer Location

Status: test
Severity: medium
Log source: category file_event, product windows
Author: Nasreddine Bencherchali (Nextron Systems)
Source: github.com/SigmaHQ/sigma

Detects the creation of a "Report.wer" file in an uncommon folder structure. This could be a sign of potential exploitation of CVE-2023-36874.

MITRE ATT&CK coverage

Tactic	Techniques
Execution	No specific technique

Telemetry coverage

Provider	Record / event type
Sysmon	Event ID 11: FileCreate

Rule body

title: Potential CVE-2023-36874 Exploitation - Uncommon Report.Wer Location
id: 92389a99-5215-43b0-a09f-e334453b2ed3
status: test
description: Detects the creation of a "Report.wer" file in an uncommon folder structure. This could be a sign of potential exploitation of CVE-2023-36874.
references:
    - https://github.com/Wh04m1001/CVE-2023-36874
    - https://www.crowdstrike.com/blog/falcon-complete-zero-day-exploit-cve-2023-36874/
author: Nasreddine Bencherchali (Nextron Systems)
date: 2023-08-23
tags:
    - attack.execution
    - cve.2023-36874
    - detection.emerging-threats
logsource:
    category: file_event
    product: windows
detection:
    selection:
        TargetFilename|contains: ':\ProgramData\Microsoft\Windows\WER\ReportArchive\'
        TargetFilename|endswith: '\Report.wer'
    filter_main_locations:
        TargetFilename|contains:
            # Note: This list is non exhaustive. Use this as a start for hunting for suspicious folder report
            - '\ReportArchive\AppCrash_'
            - '\ReportArchive\AppHang_'
            - '\ReportArchive\Critical_'
            - '\ReportArchive\Kernel_'
            - '\ReportArchive\NonCritical_'
    condition: selection and not 1 of filter_main_*
falsepositives:
    - Unknown
level: medium

Stages and Predicates

Stage 0: `condition`

selection and not 1 of filter_main_*

Stage 1: `selection`

selection:
    TargetFilename|contains: ':\ProgramData\Microsoft\Windows\WER\ReportArchive\'
    TargetFilename|endswith: '\Report.wer'

Stage 2: `not filter_main_locations`

filter_main_locations:
    TargetFilename|contains:
        - '\ReportArchive\AppCrash_'
        - '\ReportArchive\AppHang_'
        - '\ReportArchive\Critical_'
        - '\ReportArchive\Kernel_'
        - '\ReportArchive\NonCritical_'

Exclusions

The rule actively suppresses these predicates.

Field	Kind	Excluded values	Search
`TargetFilename`	match	`\ReportArchive\AppCrash_`	`excludes:TargetFilename` `field:"TargetFilename" value:"\ReportArchive\AppCrash_"`
`TargetFilename`	match	`\ReportArchive\AppHang_`	`excludes:TargetFilename` `field:"TargetFilename" value:"\ReportArchive\AppHang_"`
`TargetFilename`	match	`\ReportArchive\Critical_`	`excludes:TargetFilename` `field:"TargetFilename" value:"\ReportArchive\Critical_"`
`TargetFilename`	match	`\ReportArchive\Kernel_`	`excludes:TargetFilename` `field:"TargetFilename" value:"\ReportArchive\Kernel_"`
`TargetFilename`	match	`\ReportArchive\NonCritical_`	`excludes:TargetFilename` `field:"TargetFilename" value:"\ReportArchive\NonCritical_"`

Indicators

These rows show field, operator, and value matches.

Field	Kind	Values	Search
`TargetFilename`	ends_with	`\Report.wer`	`field:"TargetFilename" kind:ends_with value:"\Report.wer"`
`TargetFilename`	match	`:\ProgramData\Microsoft\Windows\WER\ReportArchive\`	`field:"TargetFilename" kind:match value:":\ProgramData\Microsoft\Windows\WER\ReportArchive\"`