Potential NetNTLMv1 Downgrade Attack

[rule]
description = """
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.
"""
id = "6179bd21-a2ca-40c0-bfef-77aab4e99432"
license = "Elastic License v2"
name = "Potential NetNTLMv1 Downgrade Attack"
os_list = ["windows"]
reference = [
    "https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/security-policy-settings/network-security-lan-manager-authentication-level",
]
version = "1.0.4"

query = '''
registry where event.action == "modification" and registry.value == "LmCompatibilityLevel" and registry.data.strings in ("2", "1", "0") and
/* noisy FP - need to be compensated by a detection rule */
not (user.id == "S-1-5-18" and process.name == "powershell.exe" and registry.data.strings in ("1", "0"))
'''

min_endpoint_version = "7.15.0"
optional_actions = []
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 0

[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1112"
name = "Modify Registry"
reference = "https://attack.mitre.org/techniques/T1112/"


[threat.tactic]
id = "TA0005"
name = "Defense Evasion"
reference = "https://attack.mitre.org/tactics/TA0005/"

[internal]
min_endpoint_version = "7.15.0"