Detection rules › Sigma
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 coverage
| Tactic | Techniques |
|---|---|
| Execution | T1059 Command and Scripting Interpreter, T1204 User Execution |
| Stealth | T1140 Deobfuscate/Decode Files or Information |
Event coverage
| Provider | Event | Title |
|---|---|---|
| ESF | exec | Process Execution (Notify) |
Rule body yaml
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.stealth
- attack.t1059
- attack.t1204
- attack.execution
- attack.t1140
- 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
Stages and Predicates
Stage 0: condition
selectionStage 1: selection
selection:
Image|endswith: '/openssl'
CommandLine|contains|all:
- '/Volumes/'
- 'enc'
- '-base64'
- ' -d '
Indicators
Each row is a field, operator, and value that the rule matches. The corpus column counts how many other rules in the catalog look for the same combination: high numbers point to widely-used, community-vetted indicators. Blank or 1 shows that the indicator is specific to this rule.
| Field | Kind | Values |
|---|---|---|
CommandLine | match |
|
Image | ends_with |
|