defense_evasion_microsoft_365_exchange_malware_filter_rule_mod.toml

[metadata]
creation_date = "2020/11/19"
integration = ["o365"]
maturity = "production"
updated_date = "2024/05/21"

[rule]
author = ["Elastic"]
description = """
Identifies when a malware filter rule has been deleted or disabled in Microsoft 365. An adversary or insider threat may
want to modify a malware filter rule to evade detection.
"""
false_positives = [
    """
    A malware filter rule may be deleted by a system or network administrator. Verify that the configuration change was
    expected. Exceptions can be added to this rule to filter expected behavior.
    """,
]
from = "now-30m"
index = ["filebeat-*", "logs-o365*"]
language = "kuery"
license = "Elastic License v2"
name = "Microsoft 365 Exchange Malware Filter Rule Modification"
note = """## Setup

The Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule."""
references = [
    "https://docs.microsoft.com/en-us/powershell/module/exchange/remove-malwarefilterrule?view=exchange-ps",
    "https://docs.microsoft.com/en-us/powershell/module/exchange/disable-malwarefilterrule?view=exchange-ps",
]
risk_score = 47
rule_id = "ca79768e-40e1-4e45-a097-0e5fbc876ac2"
severity = "medium"
tags = [
    "Domain: Cloud",
    "Data Source: Microsoft 365",
    "Use Case: Configuration Audit",
    "Tactic: Defense Evasion",
]
timestamp_override = "event.ingested"
type = "query"

query = '''
event.dataset:o365.audit and event.provider:Exchange and event.category:web and event.action:("Remove-MalwareFilterRule" or "Disable-MalwareFilterRule") and event.outcome:success
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1562"
name = "Impair Defenses"
reference = "https://attack.mitre.org/techniques/T1562/"


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