Module security 

Security Module - Command validation and blocklist

Provides security validation for exec: commands:

• Control character detection (blocks null bytes, escape sequences)
• Blocklist for dangerous command patterns
• Unicode NFKC normalization to prevent confusable bypass
• Full validation combining both checks

Unicode Confusable Protection

Attackers may attempt to bypass the blocklist using Unicode confusables:

• Fullwidth characters: rm vs ｒｍ (U+FF52, U+FF4D)
• Math bold/italic: sudo vs 𝘀𝘂𝗱𝗼 (U+1D600 range)
• Combining characters: rm with zero-width joiners

NFKC (Compatibility Decomposition + Canonical Composition) normalizes these variants to their ASCII equivalents before blocklist checking.

See ADR-TBD for security design decisions.

Functions

check_blocklist

Check command against blocklist

check_shell_mode_blocklist

Check command against shell-mode-specific blocklist.

sensitive_env_vars

Returns the list of sensitive env var names that should be stripped from child processes to prevent API key leakage.

strip_sensitive_env_vars

Remove sensitive API key env vars from a Command before spawning.

validate_command_string

Validate command string for control characters

validate_env_vars

Validate environment variables for dangerous names.

validate_exec_command

Full security validation for exec commands

validate_exec_command_with_shell

Full security validation for exec commands with explicit shell mode flag.