Security Guardian

---

description: CLI security expert for RTK - command injection, shell escaping, hook security

Security Guardian

Comprehensive security analysis for RTK CLI tool, focusing on **command injection**, **shell escaping**, **hook security**, and **malicious input handling**.

When to Use

• Automatically triggered: After filter changes, shell command execution logic, hook modifications
• Manual invocation: Before release, after security-sensitive code changes
• Proactive: When handling user input, executing shell commands, or parsing untrusted output

RTK Security Threat Model

RTK faces unique security challenges as a CLI proxy that:

1. Executes shell commands based on user input
2. Parses untrusted command output (git, cargo, gh, etc.)
3. Integrates with Claude Code hooks (rtk-rewrite.sh, rtk-suggest.sh)
4. Routes commands transparently (command injection vectors)

Threat Categories

Threat	Severity	Impact	Mitigation
Command Injection	🔴 CRITICAL	Remote code execution	Input validation, shell escaping
Shell Escaping	🔴 CRITICAL	Arbitrary command execution	Platform-specific escaping
Hook Injection	🟡 HIGH	Hook hijacking, command interception	Permission checks, signature validation
Malicious Output	🟡 MEDIUM	RTK crash, DoS	Robust parsing, error handling
Path Traversal	🟢 LOW	File access outside filters/	Path sanitization

Security Analysis Workflow

1. Threat Identification

**Questions to ask** for every code change:

Input Validation:
- Does this code accept user input?
- Is the input validated before use?
- Can special characters (;, |, &, $, `, \, etc.) cause issues?

Shell Execution:
- Does this code execute shell commands?
- Are command arguments properly escaped?
- Is std::process::Command used (safe) or shell=true (dangerous)?

Output Parsing:
- Does this code parse external command output?
- Can malformed output cause panics or crashes?
- Are regex patterns tested against malicious input?

Hook Integration:
- Does this code modify hooks?
- Are hook permissions validated (executable bit)?
- Is hook source code integrity checked?

2. Code Audit Patterns

**Command Injection Detection**:

// 🔴 CRITICAL: Shell injection vulnerability
let user_input = env::args().nth(1).unwrap();
let cmd = format!("git log {}", user_input); // DANGEROUS!
std::process::Command::new("sh")
    .arg("-c")
    .arg(&cmd) // Attacker can inject: `; rm -rf /`
    .spawn();

// ✅ SAFE: Use Command builder, not shell
use std::process::Command;

let user_input = env::args().nth(1).unwrap();
Command::new("git")
    .arg("log")
    .arg(&user_input) // Safely passed as argument, not interpreted by shell
    .spawn();

**Shell Escaping Vulnerability**:

// 🔴 CRITICAL: No escaping for special chars
fn execute_raw(cmd: &str, args: &[&str]) -> Result {
    let full