[metadata]
creation_date = "2023/09/27"
integration = ["endpoint"]
maturity = "production"
updated_date = "2024/05/21"

[rule]
author = ["Elastic"]
building_block_type = "default"
description = """
Identifies binaries that are loaded and with an invalid code signature. This may indicate an attempt to masquerade as a
signed binary.
"""
from = "now-119m"
index = ["logs-endpoint.events.library-*"]
interval = "60m"
language = "eql"
license = "Elastic License v2"
name = "Image Loaded with Invalid Signature"
risk_score = 21
rule_id = "fd9484f2-1c56-44ae-8b28-dc1354e3a0e8"
severity = "low"
tags = [
    "Domain: Endpoint",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Defense Evasion",
    "Rule Type: BBR",
    "Data Source: Elastic Defend",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
library where host.os.type == "windows" and event.action == "load" and
  dll.code_signature.status : ("errorUntrustedRoot", "errorBadDigest", "errorUntrustedRoot") and
  (dll.Ext.relative_file_creation_time <= 500 or dll.Ext.relative_file_name_modify_time <= 500) and
  not startswith~(dll.name, process.name) and
  not dll.path : (
    "?:\\Windows\\System32\\DriverStore\\FileRepository\\*"
  )
'''


[[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 = "T1036.001"
name = "Invalid Code Signature"
reference = "https://attack.mitre.org/techniques/T1036/001/"



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