Executable File Creation with Multiple Extensions

 1[metadata]
 2creation_date = "2021/01/19"
 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 = """
12Masquerading can allow an adversary to evade defenses and better blend in with the environment. One way it occurs is
13when the name or location of a file is manipulated as a means of tricking a user into executing what they think is a
14benign file type but is actually executable code.
15"""
16from = "now-9m"
17index = ["winlogbeat-*", "logs-endpoint.events.file-*", "logs-windows.sysmon_operational-*", "endgame-*", "logs-m365_defender.event-*", "logs-sentinel_one_cloud_funnel.*"]
18language = "eql"
19license = "Elastic License v2"
20name = "Executable File Creation with Multiple Extensions"
21risk_score = 47
22rule_id = "8b2b3a62-a598-4293-bc14-3d5fa22bb98f"
23severity = "medium"
24tags = [
25    "Domain: Endpoint",
26    "OS: Windows",
27    "Use Case: Threat Detection",
28    "Tactic: Defense Evasion",
29    "Data Source: Elastic Endgame",
30    "Data Source: Elastic Defend",
31    "Data Source: Sysmon",
32    "Data Source: Microsoft Defender for Endpoint",
33    "Data Source: SentinelOne",
34]
35timestamp_override = "event.ingested"
36type = "eql"
37
38query = '''
39file where host.os.type == "windows" and event.type == "creation" and file.extension : "exe" and
40  file.name regex~ """.*\.(vbs|vbe|bat|js|cmd|wsh|ps1|pdf|docx?|xlsx?|pptx?|txt|rtf|gif|jpg|png|bmp|hta|txt|img|iso)\.exe""" and
41  not (process.executable : ("?:\\Windows\\System32\\msiexec.exe", "C:\\Users\\*\\QGIS_SCCM\\Files\\QGIS-OSGeo4W-*-Setup-x86_64.exe") and
42       file.path : "?:\\Program Files\\QGIS *\\apps\\grass\\*.exe")
43'''
44
45
46[[rule.threat]]
47framework = "MITRE ATT&CK"
48[[rule.threat.technique]]
49id = "T1036"
50name = "Masquerading"
51reference = "https://attack.mitre.org/techniques/T1036/"
52[[rule.threat.technique.subtechnique]]
53id = "T1036.007"
54name = "Double File Extension"
55reference = "https://attack.mitre.org/techniques/T1036/007/"
56
57
58
59[rule.threat.tactic]
60id = "TA0005"
61name = "Defense Evasion"
62reference = "https://attack.mitre.org/tactics/TA0005/"
63[[rule.threat]]
64framework = "MITRE ATT&CK"
65[[rule.threat.technique]]
66id = "T1204"
67name = "User Execution"
68reference = "https://attack.mitre.org/techniques/T1204/"
69[[rule.threat.technique.subtechnique]]
70id = "T1204.002"
71name = "Malicious File"
72reference = "https://attack.mitre.org/techniques/T1204/002/"
73
74
75
76[rule.threat.tactic]
77id = "TA0002"
78name = "Execution"
79reference = "https://attack.mitre.org/tactics/TA0002/"