What is sandbox-exec?
sandbox-exec is a built-in macOS command-line utility that enables users to execute applications within a sandboxed environment. In essence, it creates a secure, isolated space where applications can run with limited access to system resources – only accessing what you explicitly permit.
The concept behind sandboxing is fundamental to modern security: by restricting what an application can access, you minimize the potential damage from malicious code or unintended behavior. Think of it as putting an application in a secure room where it can only interact with specific objects you’ve placed there.
Benefits of Application Sandboxing
Before diving into usage, let’s understand why sandboxing matters:
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Protection from malicious code: If you’re testing an unfamiliar application or script, sandboxing can prevent it from accessing sensitive files or sending data across the network.
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Damage limitation: Even trusted applications can have vulnerabilities. Sandboxing limits the potential impact if an application is compromised.
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Privacy control: You can explicitly deny applications access to personal directories like Documents, Photos, or Contacts.
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Testing environment: Developers can test how applications function with limited permissions before implementing formal App Sandbox entitlements.
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Resource restriction: Beyond security, sandboxing can limit an application’s resource consumption or network access.
Getting Started with sandbox-exec
Using sandbox-exec requires creating a sandbox profile (configuration file) that defines the rules for your secure environment. The basic syntax is:
sandbox-exec -f profile.sb command_to_run
Where profile.sb contains the rules defining what the sandboxed application can and cannot do, and command_to_run is the application you want to run within those constraints.
Understanding Sandbox Profiles
Sandbox profiles use a Scheme-like syntax (a LISP dialect) with parentheses grouping expressions. The basic structure includes:
- A version declaration:
(version 1) - Default policy:
(deny default)or(allow default) - Specific rules allowing or denying operations
Rules can target specific resources using:
- Literal paths:
(literal "/path/to/file") - Regular expressions:
(regex "^/System") - Glob patterns:
(subpath "/Library")
See Appendix for more complete list of available rules
Two Fundamental Approaches to Sandboxing
There are
