Outlook Home Page Registry Modification

 1[metadata]
 2creation_date = "2024/08/01"
 3integration = ["endpoint", "windows", "m365_defender", "sentinel_one_cloud_funnel"]
 4maturity = "production"
 5updated_date = "2024/10/15"
 6min_stack_version = "8.14.0"
 7min_stack_comments = "Breaking change at 8.14.0 for the Windows Integration."
 8
 9[rule]
10author = ["Elastic"]
11description = """
12Identifies modifications in registry keys associated with abuse of the Outlook Home Page functionality for command and
13control or persistence.
14"""
15from = "now-9m"
16index = ["winlogbeat-*", "logs-endpoint.events.registry-*", "logs-windows.sysmon_operational-*", "endgame-*", "logs-m365_defender.event-*", "logs-sentinel_one_cloud_funnel.*"]
17language = "eql"
18license = "Elastic License v2"
19name = "Outlook Home Page Registry Modification"
20references = [
21    "https://cloud.google.com/blog/topics/threat-intelligence/breaking-the-rules-tough-outlook-for-home-page-attacks/",
22    "https://github.com/trustedsec/specula"
23]
24risk_score = 47
25rule_id = "ac5a2759-5c34-440a-b0c4-51fe674611d6"
26severity = "medium"
27tags = [
28    "Domain: Endpoint",
29    "OS: Windows",
30    "Use Case: Threat Detection",
31    "Tactic: Command and Control",
32    "Tactic: Persistence",
33    "Data Source: Elastic Endgame",
34    "Data Source: Elastic Defend",
35    "Data Source: Sysmon",
36    "Data Source: Microsoft Defender for Endpoint",
37    "Data Source: SentinelOne",
38]
39timestamp_override = "event.ingested"
40type = "eql"
41
42query = '''
43registry where host.os.type == "windows" and event.action != "deletion" and registry.value : "URL" and
44    registry.path : (
45        "HKCU\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
46        "HKEY_USERS\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
47        "HKU\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
48        "\\REGISTRY\\USER\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL",
49        "USER\\*\\SOFTWARE\\Microsoft\\Office\\*\\Outlook\\Webview\\Inbox\\URL"
50    ) and registry.data.strings : "*http*"
51'''
52
53
54[[rule.threat]]
55framework = "MITRE ATT&CK"
56
57[rule.threat.tactic]
58id = "TA0011"
59name = "Command and Control"
60reference = "https://attack.mitre.org/tactics/TA0011/"
61
62[[rule.threat]]
63framework = "MITRE ATT&CK"
64[[rule.threat.technique]]
65id = "T1137"
66name = "Office Application Startup"
67reference = "https://attack.mitre.org/techniques/T1137/"
68[[rule.threat.technique.subtechnique]]
69id = "T1137.004"
70name = "Outlook Home Page"
71reference = "https://attack.mitre.org/techniques/T1137/004/"
72
73
74
75[rule.threat.tactic]
76id = "TA0003"
77name = "Persistence"
78reference = "https://attack.mitre.org/tactics/TA0003/"