Sigma rule: Suspicious Browser Child Process - MacOS

Rule

Title

Suspicious Browser Child Process - MacOS

Status

test

Level

medium

Author

Sohan G (D4rkCiph3r)

Date

2023-04-05

File

rules/macos/process_creation/proc_creation_macos_susp_browser_child_process.yml

Commit

ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects suspicious child processes spawned from browsers. This could be a result of a potential web browser exploitation.

Log source

product

macos

category

process_creation

Detection

selection:
    ParentImage|contains:
        - 'com.apple.WebKit.WebContent'
        - 'firefox'
        - 'Google Chrome Helper'
        - 'Google Chrome'
        - 'Microsoft Edge'
        - 'Opera'
        - 'Safari'
        - 'Tor Browser'
    Image|endswith:
        - '/bash'
        - '/curl'
        - '/dash'
        - '/ksh'
        - '/osascript'
        - '/perl'
        - '/php'
        - '/pwsh'
        - '/python'
        - '/sh'
        - '/tcsh'
        - '/wget'
        - '/zsh'
filter_main_generic:
    CommandLine|contains: '--defaults-torrc' # Informs tor to use default config file
filter_main_ms_autoupdate:
    CommandLine|contains: '/Library/Application Support/Microsoft/MAU*/Microsoft AutoUpdate.app/Contents/MacOS/msupdate' # Microsoft AutoUpdate utility
filter_main_chrome:
    ParentImage|contains:
        - 'Google Chrome Helper'
        - 'Google Chrome'
    CommandLine|contains:
        - '/Volumes/Google Chrome/Google Chrome.app/Contents/Frameworks/*/Resources/install.sh' # Install the Google Chrome browser
        - '/Applications/Google Chrome.app/Contents/Frameworks/Google Chrome Framework.framework/*/Resources/keystone_promote_preflight.sh' # Updates the Google Chrome branding configuration files
        - '/Applications/Google Chrome.app/Contents/Frameworks/Google Chrome Framework.framework/*/Resources/keystone_promote_postflight.sh' # Script that performs the post-installation tasks
filter_main_ms_edge:
    ParentImage|contains: 'Microsoft Edge'
    CommandLine|contains:
        - 'IOPlatformExpertDevice' # Retrieves the IOPlatformUUID (parent process - Microsoft Edge)
        - 'hw.model' # Retrieves model name of the computer's hardware (parent process - Microsoft Edge)
filter_main_chromerecovery:
    ParentImage|contains:
        - 'Google Chrome Helper'
        - 'Google Chrome'
    CommandLine|contains|all:
        - '/Users/'
        - '/Library/Application Support/Google/Chrome/recovery/'
        - '/ChromeRecovery'
filter_optional_null:
    # Aoids alerting for the events which do not have command-line arguments
    CommandLine: null
filter_optional_empty:
    # Aoids alerting for the events which do not have command-line arguments
    CommandLine: ''
condition: selection and not 1 of filter_main_* and not 1 of filter_optional_*

False positives (as the rule lists them)

• Legitimate browser install, update and recovery scripts

Tags

• attack.initial-access
• attack.execution
• attack.t1189
• attack.t1203
• attack.t1059

MITRE ATT&CK ids this rule names

• T1059
• T1189
• T1203

References

• https://fr.slideshare.net/codeblue_jp/cb19-recent-apt-attack-on-crypto-exchange-employees-by-heungsoo-kang
• https://github.com/elastic/detection-rules/blob/4312d8c9583be524578a14fe6295c3370b9a9307/rules/macos/execution_initial_access_suspicious_browser_childproc.toml

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/macos/process_creation/proc_creation_macos_susp_browser_child_process.yml