sigma-rules/rules/macos/execution_installer_package_spawned_network_event.toml

[metadata]
creation_date = "2021/02/23"
maturity = "production"
updated_date = "2022/08/17"

[rule]
author = ["Elastic"]
description = """
Detects the execution of a MacOS installer package with an abnormal child process (e.g bash) followed immediately by a network connection via a suspicious process (e.g curl). 
Threat actors will build and distribute malicious MacOS installer packages, which have a .pkg extension, many times imitating valid software in order to persuade and infect their victims often using the package files (e.g pre/post install scripts etc.) to download additional tools or malicious software. 
If this rule fires it should indicate the installation of a malicious or suspicious package.
"""
false_positives = [
    """
    Custom organization-specific macOS packages that use .pkg files to run cURL could trigger this rule. If known
    behavior is causing false positives, it can be excluded from the rule.
    """,
]
from = "now-9m"
index = ["logs-endpoint.events.*"]
language = "eql"
license = "Elastic License v2"
name = "MacOS Installer Package Spawns Network Event"
references = [
    "https://redcanary.com/blog/clipping-silver-sparrows-wings",
    "https://posts.specterops.io/introducing-mystikal-4fbd2f7ae520",
    "https://github.com/D00MFist/Mystikal"
]
risk_score = 47
rule_id = "99239e7d-b0d4-46e3-8609-acafcf99f68c"
severity = "medium"
tags = ["Elastic", "Host", "macOS", "Threat Detection", "Execution", "Command and Control"]
type = "eql"

query = '''
sequence by host.id, user.id with maxspan=30s
[process where event.type == "start" and event.action == "exec" and process.parent.name : ("installer", "package_script_service") and process.name : ("bash", "sh", "zsh", "python", "osascript", "tclsh*")] 
[network where event.type == "start" and process.name : ("curl", "osascript", "wget", "python")] 
'''

[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"
[[rule.threat.technique.subtechnique]]
id = "T1059.007"
name = "JavaScript"
reference = "https://attack.mitre.org/techniques/T1059/007/"



[rule.threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"
[[rule.threat]]
framework = "MITRE ATT&CK"
[[rule.threat.technique]]
id = "T1071"
name = "Application Layer Protocol"
reference = "https://attack.mitre.org/techniques/T1071/"
[[rule.threat.technique.subtechnique]]
id = "T1071.001"
name = "Web Protocols"
reference = "https://attack.mitre.org/techniques/T1071/001/"



[rule.threat.tactic]
id = "TA0011"
name = "Command and Control"
reference = "https://attack.mitre.org/tactics/TA0011/"