Executable File Creation with Multiple Extensions

 1[metadata]
 2creation_date = "2021/01/19"
 3integration = ["endpoint", "windows"]
 4maturity = "production"
 5min_stack_comments = "New fields added: required_fields, related_integrations, setup"
 6min_stack_version = "8.3.0"
 7updated_date = "2023/06/22"
 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.*", "logs-windows.*", "endgame-*"]
18language = "eql"
19license = "Elastic License v2"
20name = "Executable File Creation with Multiple Extensions"
21note = """## Setup
22
23If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2, events will not define `event.ingested` and default fallback for EQL rules was not added until 8.2, so you will need to add a custom pipeline to populate `event.ingested` to @timestamp for this rule to work.
24"""
25risk_score = 47
26rule_id = "8b2b3a62-a598-4293-bc14-3d5fa22bb98f"
27severity = "medium"
28tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Defense Evasion", "Data Source: Elastic Endgame", "Data Source: Elastic Defend"]
29timestamp_override = "event.ingested"
30type = "eql"
31
32query = '''
33file where host.os.type == "windows" and event.type == "creation" and file.extension : "exe" and
34  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
35  not (process.executable : ("?:\\Windows\\System32\\msiexec.exe", "C:\\Users\\*\\QGIS_SCCM\\Files\\QGIS-OSGeo4W-*-Setup-x86_64.exe") and
36       file.path : "?:\\Program Files\\QGIS *\\apps\\grass\\*.exe") and
37  not process.executable : ("/bin/sh", "/usr/sbin/MailScanner", "/usr/bin/perl")
38'''
39
40
41[[rule.threat]]
42framework = "MITRE ATT&CK"
43[[rule.threat.technique]]
44id = "T1036"
45name = "Masquerading"
46reference = "https://attack.mitre.org/techniques/T1036/"
47[[rule.threat.technique.subtechnique]]
48id = "T1036.007"
49name = "Double File Extension"
50reference = "https://attack.mitre.org/techniques/T1036/007/"
51
52
53
54[rule.threat.tactic]
55id = "TA0005"
56name = "Defense Evasion"
57reference = "https://attack.mitre.org/tactics/TA0005/"
58[[rule.threat]]
59framework = "MITRE ATT&CK"
60[[rule.threat.technique]]
61id = "T1204"
62name = "User Execution"
63reference = "https://attack.mitre.org/techniques/T1204/"
64[[rule.threat.technique.subtechnique]]
65id = "T1204.002"
66name = "Malicious File"
67reference = "https://attack.mitre.org/techniques/T1204/002/"
68
69
70
71[rule.threat.tactic]
72id = "TA0002"
73name = "Execution"
74reference = "https://attack.mitre.org/tactics/TA0002/"