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Elastic Docs ›Elastic Security Solution [8.4] ›Detections and alerts ›Prebuilt rule reference

MacOS Installer Package Spawns Network Event

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MacOS Installer Package Spawns Network Event

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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.

Rule type: eql

Rule indices:

  • logs-endpoint.events.*

Severity: medium

Risk score: 74

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

  • Elastic
  • Host
  • macOS
  • Threat Detection
  • Execution
  • Command and Control

Version: 6 (version history)

Added (Elastic Stack release): 7.12.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic

Rule license: Elastic License v2

Potential false positives

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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.

Rule query

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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")]

Threat mapping

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Framework: MITRE ATT&CKTM

Rule version history

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Version 6 (8.4.0 release)
  • Rule name changed from: macOS Installer Spawns Network Event

  • Updated query, changed from:

    sequence by process.entity_id with maxspan=1m [process where
event.type == "start" and host.os.family == "macos" and
process.parent.executable in ("/usr/sbin/installer",
"/System/Library/CoreServices/Installer.app/Contents/MacOS/Installer")
] [network where not cidrmatch(destination.ip, "10.0.0.0/8",
"127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24",
"192.0.0.0/29", "192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32",
"192.0.0.170/32", "192.0.0.171/32", "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", "224.0.0.0/4",
"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", "240.0.0.0/4", "::1",
"FE80::/10", "FF00::/8")]
Version 4 (8.2.0 release)
  • Formatting only
Version 3 (7.15.0 release)
  • Formatting only
Version 2 (7.14.0 release)

  • Updated query, changed from:

    sequence by process.entity_id with maxspan=1m [ process where
event.type == "start" and host.os.family == "macos" and
process.parent.executable in ("/usr/sbin/installer",
"/System/Library/CoreServices/Installer.app/Contents/MacOS/Installer")
] [ network where not cidrmatch(destination.ip,
"192.168.0.0/16", "10.0.0.0/8", "172.16.0.0/12",
"224.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16",
"::1", "FE80::/10", "FF00::/8") ]
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