Potential Masquerading as VLC DLL

ELASTIC detection rule by Elastic · Elastic License v2

Identifies instances of VLC-related DLLs which are not signed by the original developer. Attackers may name their payload as legitimate applications to blend into the environment, or embedding its malicious code within legitimate applications to deceive machine learning algorithms by incorporating authentic and benign code.

[metadata]
bypass_bbr_timing = true
creation_date = "2023/08/09"
integration = ["endpoint"]
maturity = "production"
updated_date = "2024/05/05"

[rule]
author = ["Elastic"]
building_block_type = "default"
description = """
Identifies instances of VLC-related DLLs which are not signed by the original developer. Attackers may name their
payload as legitimate applications to blend into the environment, or embedding its malicious code within legitimate
applications to deceive machine learning algorithms by incorporating authentic and benign code.
"""
from = "now-9m"
index = ["logs-endpoint.events.library-*"]
language = "eql"
license = "Elastic License v2"
name = "Potential Masquerading as VLC DLL"
risk_score = 21
rule_id = "4494c14f-5ff8-4ed2-8e99-bf816a1642fc"
severity = "low"
tags = [
    "Domain: Endpoint",
    "Data Source: Elastic Defend",
    "OS: Windows",
    "Use Case: Threat Detection",
    "Tactic: Defense Evasion",
    "Tactic: Persistence",
    "Rule Type: BBR",
]
timestamp_override = "event.ingested"
type = "eql"

query = '''
library where host.os.type == "windows" and event.action == "load" and
  dll.name : ("libvlc.dll", "libvlccore.dll", "axvlc.dll") and
  not (
    dll.code_signature.subject_name : ("VideoLAN", "716F2E5E-A03A-486B-BC67-9B18474B9D51")
    and dll.code_signature.trusted == true
  )
'''


[[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.technique.subtechnique]]
id = "T1036.005"
name = "Match Legitimate Resource Name or Location"
reference = "https://attack.mitre.org/techniques/T1036/005/"



[rule.threat.tactic]
id = "TA0005"
name = "Defense Evasion"
reference = "https://attack.mitre.org/tactics/TA0005/"
[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1554"
name = "Compromise Host Software Binary"
reference = "https://attack.mitre.org/techniques/T1554/"


[rule.threat.tactic]
id = "TA0003"
name = "Persistence"
reference = "https://attack.mitre.org/tactics/TA0003/"

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

ebfaa015-2548-490b-b669-c0e9862f1fd6

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Executable code, not a declarative rule

This submission is arbitrary [[ currentRule.format ? currentRule.format.toUpperCase() : '' ]] code, not a declarative detection rule — review it as you would any script before running it, and note that it cannot be safely aggregated or auto-executed alongside YARA/Sigma/Suricata/CRS rules.

Rejected pattern present

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Format & documentation suggestions

Not a security issue — this rule is valid and was accepted as-is. These are optional fields/conventions its own format recommends, mainly affecting its quality score and how well it documents itself for other reviewers.

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What do these messages mean?

[[ currentRule.title && currentRule.title.length > 60 ? currentRule.title.slice(0, 60) + '…' : currentRule.title ]]

[[ currentRule.title ]]

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