Elastic Security Detection Rules

Potential NetNTLMv1 Downgrade Attack

Last updated 9 days ago on 2025-04-14
Created 9 days ago on 2025-04-14

About

Identifies registry modification to force the system to fall back to NTLMv1 for authentication. This modification is possible with local administrator privileges and is commonly referred to as a `NetNTLMv1 downgrade attack`.
Tags
Domain: EndpointOS: WindowsUse Case: Threat DetectionTactic: Defense EvasionData Source: Elastic DefendData Source: Elastic EndgameData Source: Microsoft Defender for EndpointData Source: SentinelOneData Source: SysmonLanguage: eql
Severity
medium
Risk Score
47
MITRE ATT&CK™

Defense Evasion (TA0005)(opens in a new tab or window)

↳ Modify Registry (T1112)(opens in a new tab or window)

↳ Impair Defenses (T1562)(opens in a new tab or window)

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

Definition

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

endpoint(opens in a new tab or window)

m365_defender(opens in a new tab or window)

sentinel_one_cloud_funnel(opens in a new tab or window)

windows(opens in a new tab or window)

Query
registry where host.os.type == "windows" and event.action != "deletion" and
 registry.value == "LmCompatibilityLevel" and registry.data.strings in ("2", "1", "0", "0x00000002", "0x00000001", "0x00000000")

Install detection rules in Elastic Security

Detect Potential NetNTLMv1 Downgrade Attack 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(opens in a new tab or window).