Executable File Creation with Multiple Extensions

 1[metadata]
 2creation_date = "2021/01/19"
 3integration = ["endpoint", "windows", "m365_defender"]
 4maturity = "production"
 5updated_date = "2024/06/25"
 6
 7[rule]
 8author = ["Elastic"]
 9description = """
10Masquerading can allow an adversary to evade defenses and better blend in with the environment. One way it occurs is
11when the name or location of a file is manipulated as a means of tricking a user into executing what they think is a
12benign file type but is actually executable code.
13"""
14from = "now-9m"
15index = ["winlogbeat-*", "logs-endpoint.events.file-*", "logs-windows.sysmon_operational-*", "endgame-*", "logs-m365_defender.event-*"]
16language = "eql"
17license = "Elastic License v2"
18name = "Executable File Creation with Multiple Extensions"
19risk_score = 47
20rule_id = "8b2b3a62-a598-4293-bc14-3d5fa22bb98f"
21setup = """## Setup
22
23If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2,
24events will not define `event.ingested` and default fallback for EQL rules was not added until version 8.2.
25Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate
26`event.ingested` to @timestamp.
27For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html
28"""
29severity = "medium"
30tags = [
31    "Domain: Endpoint",
32    "OS: Windows",
33    "Use Case: Threat Detection",
34    "Tactic: Defense Evasion",
35    "Data Source: Elastic Endgame",
36    "Data Source: Elastic Defend",
37    "Data Source: Sysmon",
38    "Data Source: Microsoft Defender for Endpoint"
39]
40timestamp_override = "event.ingested"
41type = "eql"
42
43query = '''
44file where host.os.type == "windows" and event.type == "creation" and file.extension : "exe" and
45  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
46  not (process.executable : ("?:\\Windows\\System32\\msiexec.exe", "C:\\Users\\*\\QGIS_SCCM\\Files\\QGIS-OSGeo4W-*-Setup-x86_64.exe") and
47       file.path : "?:\\Program Files\\QGIS *\\apps\\grass\\*.exe")
48'''
49
50
51[[rule.threat]]
52framework = "MITRE ATT&CK"
53[[rule.threat.technique]]
54id = "T1036"
55name = "Masquerading"
56reference = "https://attack.mitre.org/techniques/T1036/"
57[[rule.threat.technique.subtechnique]]
58id = "T1036.007"
59name = "Double File Extension"
60reference = "https://attack.mitre.org/techniques/T1036/007/"
61
62
63
64[rule.threat.tactic]
65id = "TA0005"
66name = "Defense Evasion"
67reference = "https://attack.mitre.org/tactics/TA0005/"
68[[rule.threat]]
69framework = "MITRE ATT&CK"
70[[rule.threat.technique]]
71id = "T1204"
72name = "User Execution"
73reference = "https://attack.mitre.org/techniques/T1204/"
74[[rule.threat.technique.subtechnique]]
75id = "T1204.002"
76name = "Malicious File"
77reference = "https://attack.mitre.org/techniques/T1204/002/"
78
79
80
81[rule.threat.tactic]
82id = "TA0002"
83name = "Execution"
84reference = "https://attack.mitre.org/tactics/TA0002/"