Elastic Security Detection Rules

Potential Notepad Markdown RCE Exploitation

Last updated 9 days ago on 2026-02-16
Created 9 days ago on 2026-02-16

About

Identifies a process started by Notepad after opening a Markdown file. This may indicate successful exploitation of a Notepad markdown parsing vulnerability (CVE-2026-20841) that can lead to arbitrary code execution.
Tags
Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: ExecutionData Source: Elastic EndgameData Source: Elastic DefendData Source: Microsoft Defender for EndpointData Source: SysmonData Source: SentinelOneLanguage: eql
Severity
high
Risk Score
73
MITRE ATT&CK™

Execution (TA0002)(external, opens in a new tab or window)

↳ Exploitation for Client Execution (T1203)(external, opens in a new tab or window)

License
Elastic License v2(external, opens in a new tab or window)

Definition

Rule Type
Event Correlation Rule
Integration Pack
Prebuilt Security Detection Rules
Index Patterns
endgame-*logs-endpoint.events.process-*logs-m365_defender.event-*logs-sentinel_one_cloud_funnel.*logs-windows.sysmon_operational-*
Related Integrations

endpoint(external, opens in a new tab or window)

windows(external, opens in a new tab or window)

m365_defender(external, opens in a new tab or window)

sentinel_one_cloud_funnel(external, opens in a new tab or window)

Query
text code block:
process where host.os.type == "windows" and event.type == "start" and
  process.parent.name : "notepad.exe" and process.parent.args : "*.md"

Install detection rules in Elastic Security

Detect Potential Notepad Markdown RCE Exploitation in the Elastic Security detection engine by installing this rule into your Elastic Stack.

To setup this rule, check out the installation guide for Prebuilt Security Detection Rules(external, opens in a new tab or window).