Microsoft 365 Exchange DKIM Signing Configuration Disabled

 1[metadata]
 2creation_date = "2020/11/18"
 3integration = ["o365"]
 4maturity = "production"
 5updated_date = "2024/05/21"
 6
 7[rule]
 8author = ["Elastic"]
 9description = """
10Identifies when a DomainKeys Identified Mail (DKIM) signing configuration is disabled in Microsoft 365. With DKIM in
11Microsoft 365, messages that are sent from Exchange Online will be cryptographically signed. This will allow the
12receiving email system to validate that the messages were generated by a server that the organization authorized and
13were not spoofed.
14"""
15false_positives = [
16    """
17    Disabling a DKIM configuration may be done by a system or network administrator. Verify that the configuration
18    change was expected. Exceptions can be added to this rule to filter expected behavior.
19    """,
20]
21from = "now-30m"
22index = ["filebeat-*", "logs-o365*"]
23language = "kuery"
24license = "Elastic License v2"
25name = "Microsoft 365 Exchange DKIM Signing Configuration Disabled"
26note = """## Setup
27
28The Office 365 Logs Fleet integration, Filebeat module, or similarly structured data is required to be compatible with this rule."""
29references = [
30    "https://docs.microsoft.com/en-us/powershell/module/exchange/set-dkimsigningconfig?view=exchange-ps",
31]
32risk_score = 47
33rule_id = "514121ce-c7b6-474a-8237-68ff71672379"
34severity = "medium"
35tags = ["Domain: Cloud", "Data Source: Microsoft 365", "Tactic: Persistence"]
36timestamp_override = "event.ingested"
37type = "query"
38
39query = '''
40event.dataset:o365.audit and event.provider:Exchange and event.category:web and event.action:"Set-DkimSigningConfig" and o365.audit.Parameters.Enabled:False and event.outcome:success
41'''
42
43
44[[rule.threat]]
45framework = "MITRE ATT&CK"
46[[rule.threat.technique]]
47id = "T1556"
48name = "Modify Authentication Process"
49reference = "https://attack.mitre.org/techniques/T1556/"
50
51
52[rule.threat.tactic]
53id = "TA0003"
54name = "Persistence"
55reference = "https://attack.mitre.org/tactics/TA0003/"