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Payload Decoded and Decrypted via Built-in Utilities

Detects when a built-in utility is used to decode and decrypt a payload after a macOS disk image (DMG) is executed. Malware authors may attempt to evade detection and trick users into executing malicious code by encoding and encrypting their payload and placing it in a disk image file. This behavior is consistent with adware or malware families such as Bundlore and Shlayer.

MITRE ATT&CK

T1059T1204T1140S0482S0402
executiondefense-evasion

Detection Query

selection:
  Image|endswith: /openssl
  CommandLine|contains|all:
    - /Volumes/
    - enc
    - -base64
    - " -d "
condition: selection

Author

Tim Rauch (rule), Elastic (idea)

Created

2022-10-17

Data Sources

macosProcess Creation Events

Platforms

macos

References

Tags

attack.t1059attack.t1204attack.executionattack.t1140attack.defense-evasionattack.s0482attack.s0402
Raw Content
title: Payload Decoded and Decrypted via Built-in Utilities
id: 234dc5df-40b5-49d1-bf53-0d44ce778eca
status: test
description: Detects when a built-in utility is used to decode and decrypt a payload after a macOS disk image (DMG) is executed. Malware authors may attempt to evade detection and trick users into executing malicious code by encoding and encrypting their payload and placing it in a disk image file. This behavior is consistent with adware or malware families such as Bundlore and Shlayer.
references:
    - https://github.com/elastic/protections-artifacts/commit/746086721fd385d9f5c6647cada1788db4aea95f#diff-5d42c3d772e04f1e8d0eb60f5233bc79def1ea73105a2d8822f44164f77ef823
author: Tim Rauch (rule), Elastic (idea)
date: 2022-10-17
tags:
    - attack.t1059
    - attack.t1204
    - attack.execution
    - attack.t1140
    - attack.defense-evasion
    - attack.s0482
    - attack.s0402
logsource:
    category: process_creation
    product: macos
detection:
    selection:
        Image|endswith: '/openssl'
        CommandLine|contains|all:
            - '/Volumes/'
            - 'enc'
            - '-base64'
            - ' -d '
    condition: selection
falsepositives:
    - Unknown
level: medium