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 = "2024/03/28"
 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-*"]
18language = "eql"
19license = "Elastic License v2"
20name = "Executable File Creation with Multiple Extensions"
21risk_score = 47
22rule_id = "8b2b3a62-a598-4293-bc14-3d5fa22bb98f"
23setup = """## Setup
24
25If enabling an EQL rule on a non-elastic-agent index (such as beats) for versions <8.2,
26events will not define `event.ingested` and default fallback for EQL rules was not added until version 8.2.
27Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate
28`event.ingested` to @timestamp.
29For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html
30"""
31severity = "medium"
32tags = ["Domain: Endpoint", "OS: Windows", "Use Case: Threat Detection", "Tactic: Defense Evasion", "Data Source: Elastic Endgame", "Data Source: Elastic Defend", "Data Source: Sysmon"]
33timestamp_override = "event.ingested"
34type = "eql"
35
36query = '''
37file where host.os.type == "windows" and event.type == "creation" and file.extension : "exe" and
38  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
39  not (process.executable : ("?:\\Windows\\System32\\msiexec.exe", "C:\\Users\\*\\QGIS_SCCM\\Files\\QGIS-OSGeo4W-*-Setup-x86_64.exe") and
40       file.path : "?:\\Program Files\\QGIS *\\apps\\grass\\*.exe") and
41  not process.executable : ("/bin/sh", "/usr/sbin/MailScanner", "/usr/bin/perl")
42'''
43
44
45[[rule.threat]]
46framework = "MITRE ATT&CK"
47[[rule.threat.technique]]
48id = "T1036"
49name = "Masquerading"
50reference = "https://attack.mitre.org/techniques/T1036/"
51[[rule.threat.technique.subtechnique]]
52id = "T1036.007"
53name = "Double File Extension"
54reference = "https://attack.mitre.org/techniques/T1036/007/"
55
56
57
58[rule.threat.tactic]
59id = "TA0005"
60name = "Defense Evasion"
61reference = "https://attack.mitre.org/tactics/TA0005/"
62[[rule.threat]]
63framework = "MITRE ATT&CK"
64[[rule.threat.technique]]
65id = "T1204"
66name = "User Execution"
67reference = "https://attack.mitre.org/techniques/T1204/"
68[[rule.threat.technique.subtechnique]]
69id = "T1204.002"
70name = "Malicious File"
71reference = "https://attack.mitre.org/techniques/T1204/002/"
72
73
74
75[rule.threat.tactic]
76id = "TA0002"
77name = "Execution"
78reference = "https://attack.mitre.org/tactics/TA0002/"