Detection rules › Elastic
Image Loaded with Invalid Signature
Identifies binaries that are loaded and with an invalid code signature. This may indicate an attempt to masquerade as a signed binary.
MITRE ATT&CK coverage
| Tactic | Techniques |
|---|---|
| Stealth | T1036.001 Masquerading: Invalid Code Signature |
Event coverage
| Provider | Event | Title |
|---|---|---|
| Sysmon | Event ID 7 | Image loaded |
Rule body elastic
[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/"
Stages and Predicates
Stage 1: library
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\\*"
)
Exclusions
Top-level NOT(...) conjuncts: predicates this rule actively suppresses.
| Field | Kind | Excluded values |
|---|---|---|
dll.name | starts_with | process.name |
dll.path | starts_with | ?:\Windows\System32\DriverStore\FileRepository\ |
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
dll.Ext.relative_file_creation_time | le |
|
dll.Ext.relative_file_name_modify_time | le |
|
dll.code_signature.status | wildcard |
|
event.action | eq |
|