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Posture check · Group Policy

Group Policy sends LAN Manager or NTLMv1 responses ​(T1557, ​T1550.002)

This policy lets computers send LAN Manager or NTLMv1 responses when they authenticate to other systems.

Why it matters

These responses can be cracked or relayed, which gives an attacker on the network the account's password or a session as that account.

How GraphnAI finds it

It runs after every sync, on each connected domain or tenant on its own. It applies to Active Directory.

It reads:

  • The directory attributes gPLink, gPOptions, flags, userAccountControl, accountEnabled and distinguishedName
  • The Group Policy files the Identity Bridge reads from SYSVOL

Tiered Fidelity™ level: Theoretical

Every finding from this check carries the Theoretical level.

  1. TheoreticalThis checkConfigured in the directory. Nothing else checked.
  2. ConstrainedA constraint on it has been checked.
  3. ValidatedTelemetry has seen it in use.

Why there's no automatic fix

GraphnAI can't edit Group Policy settings. Change this setting in Group Policy Management.

How to fix it

Set 'Network security: LAN Manager authentication level' to at least 'Send NTLMv2 response only'.

Related checks

MITRE ATT&CK® technique names and MITRE D3FEND™ technique labels: © The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. ATT&CK® is a registered trademark and D3FEND™ a trademark of The MITRE Corporation.

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