Initial Access via Audio Unit Plug-in

[rule]
description = """
Detects when an audio plug-in is manually loaded by the auval or auvaltool process followed by an immediate outbound
network connection. Applications such as GarageBand 10, Logic Pro X, Audacity, etc., use audio unit plug-ins to create
sound effects and virtual instruments. Software developers and sound engineers can create either audio components or
virtual studio technology (VST) plug-ins. Threat actors can also create audio components or plug-ins and load them to
execute unsigned code via the native auval or auvaltool binaries.
"""
id = "5faec4a7-c62b-492e-83db-dc7b8eec0878"
license = "Elastic License v2"
name = "Initial Access via Audio Unit Plug-in"
os_list = ["macos"]
reference = ["https://posts.specterops.io/audio-unit-plug-ins-896d3434a882"]
version = "1.0.10"

query = '''
sequence by process.entity_id with maxspan=1m
[process where event.type == "start" and event.action == "exec" and 
  process.name in ("auvaltool", "auval") and
  process.args in ("-a", "-v") and 
  not process.parent.executable in ("/Applications/Logic Pro X.app/Contents/MacOS/Logic Pro X",
                                    "/Applications/Logic Pro.app/Contents/MacOS/Logic Pro", 
                                    "/sbin/launchd")]
[network where event.type == "start" and event.action == "connection_attempted" and
   not cidrmatch(destination.ip, 
       "240.0.0.0/4", "233.252.0.0/24", "224.0.0.0/4", "198.19.0.0/16", "192.18.0.0/15", 
       "192.0.0.0/24", "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", 
       "192.0.2.0/24", "192.31.196.0/24", "192.52.193.0/24", "192.168.0.0/16", "192.88.99.0/24", 
       "100.64.0.0/10", "192.175.48.0/24", "198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24",
       "::1", "FE80::/10", "FF00::/8")]
'''

min_endpoint_version = "8.16.0"
[[actions]]
action = "kill_process"
field = "process.entity_id"
state = 0

[[optional_actions]]
action = "rollback"
field = "process.entity_id"
state = 0

[[threat]]
framework = "MITRE ATT&CK"
[[threat.technique]]
id = "T1059"
name = "Command and Scripting Interpreter"
reference = "https://attack.mitre.org/techniques/T1059/"
[[threat.technique.subtechnique]]
id = "T1059.004"
name = "Unix Shell"
reference = "https://attack.mitre.org/techniques/T1059/004/"



[threat.tactic]
id = "TA0002"
name = "Execution"
reference = "https://attack.mitre.org/tactics/TA0002/"

[internal]
min_endpoint_version = "8.16.0"