defense_evasion_masquerading_space_after_filename.toml

[metadata]
creation_date = "2022/10/18"
integration = ["endpoint"]
maturity = "production"
updated_date = "2024/05/21"

[rule]
author = ["Elastic"]
description = """
This rules identifies a process created from an executable with a space appended to the end of the filename. This may
indicate an attempt to masquerade a malicious file as benign to gain user execution. When a space is added to the end of
certain files, the OS will execute the file according to it's true filetype instead of it's extension. Adversaries can
hide a program's true filetype by changing the extension of the file. They can then add a space to the end of the name
so that the OS automatically executes the file when it's double-clicked.
"""
from = "now-9m"
index = ["auditbeat-*", "logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "Masquerading Space After Filename"
references = [
    "https://www.picussecurity.com/resource/blog/picus-10-critical-mitre-attck-techniques-t1036-masquerading",
]
risk_score = 47
rule_id = "f5fb4598-4f10-11ed-bdc3-0242ac120002"
setup = """## Setup

If 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 version 8.2.
Hence for this rule to work effectively, users will need to add a custom ingest pipeline to populate
`event.ingested` to @timestamp.
For more details on adding a custom ingest pipeline refer - https://www.elastic.co/guide/en/fleet/current/data-streams-pipeline-tutorial.html
"""
severity = "medium"
tags = [
    "Domain: Endpoint",
    "OS: Linux",
    "OS: macOS",
    "Use Case: Threat Detection",
    "Tactic: Defense Evasion",
    "Data Source: Elastic Defend",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
process where host.os.type:("linux","macos") and
  event.type == "start" and
  (process.executable regex~ """/[a-z0-9\s_\-\\./]+\s""") and not
  process.name in ("ls", "find", "grep", "xkbcomp")
'''


[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1036"
name = "Masquerading"
reference = "https://attack.mitre.org/techniques/T1036/"
[[rule.threat.technique.subtechnique]]
id = "T1036.006"
name = "Space after Filename"
reference = "https://attack.mitre.org/techniques/T1036/006/"



[rule.threat.tactic]
id = "TA0005"
name = "Defense Evasion"
reference = "https://attack.mitre.org/tactics/TA0005/"