The Script programming language is designed with security as a first-class concern. This document outlines the security features, best practices, and considerations when working with Script.

Script includes comprehensive protection against DoS attacks during compilation:

• Timeout Protection: All compilation phases have configurable timeouts
• Memory Limits: System memory usage is monitored and bounded
• Iteration Limits: Recursive operations have maximum iteration counts
• Recursion Depth: Stack overflow protection through depth tracking
• Specialization Limits: Generic instantiation explosion prevention

use script_lang::compilation::resource_limits::ResourceLimits;

// Production environment (secure defaults)
let limits = ResourceLimits::production();

// Development environment (more permissive)
let limits = ResourceLimits::development();

// Custom limits
let limits = ResourceLimits::custom()
    .max_iterations(10_000)
    .phase_timeout(Duration::from_secs(30))
    .max_memory_bytes(512 * 1024 * 1024) // 512MB
    .build()?;

• All array accesses include runtime bounds checking
• Negative index detection
• Automatic length validation
• Panic-on-violation with clear error messages

let arr = [1, 2, 3];
let val = arr[10]; // Runtime panic: "Array index 10 out of bounds (length: 3)"

• Automatic null pointer detection in field access
• Runtime validation of object references
• Memory corruption prevention

• Compile-time field existence checking
• Type-safe field offset calculation
• Prevention of invalid memory access

• Specialization explosion prevention
• Type variable limit enforcement
• Constraint system protection

• Proper Arc reference counting in async operations
• FFI pointer lifetime tracking
• Race condition elimination

• Bounded async state allocation
• Automatic cleanup of async resources
• Overflow protection in state machines

// Use production resource limits in production
let context = CompilationContext::with_resource_limits(
    ResourceLimits::production()
);

// Enable all security features
let bounds_checker = BoundsChecker::new(BoundsCheckMode::Always);

// More permissive limits for development
let context = CompilationContext::for_development();

When processing external Script code, always use restrictive resource limits:

let limits = ResourceLimits::custom()
    .max_iterations(1_000)           // Low iteration limit
    .phase_timeout(Duration::from_secs(10))  // Short timeout
    .max_memory_bytes(50 * 1024 * 1024)     // 50MB limit
    .build()?;

let mut context = CompilationContext::with_resource_limits(limits);

• Validate user-defined struct/enum definitions
• Limit nesting depth for complex types
• Prevent recursive type definitions

// Safe array access with bounds checking
fn safe_access(arr: [i32], index: i32) -> Option<i32> {
    if index >= 0 && index < arr.length {
        Some(arr[index])
    } else {
        None
    }
}

// Use Result types for potentially failing operations
fn divide(a: i32, b: i32) -> Result<i32, String> {
    if b == 0 {
        Err("Division by zero")
    } else {
        Ok(a / b)
    }
}

Attack Vector: Malicious code that consumes excessive compilation resources

Mitigation: Comprehensive resource monitoring and limits

• Timeout enforcement at all compilation phases
• Memory usage tracking and limits
• Iteration count restrictions
• Specialization explosion prevention

Example Protection:

// This will be caught and prevented
fn recursive_type_bomb() {
    // Attempting to create exponential type specializations
    // Compiler will abort with security violation
}

Attack Vector: Buffer overflows through array access or pointer manipulation

Mitigation: Runtime bounds checking and memory safety

• All array accesses validated at runtime
• Negative index detection
• Null pointer protection
• Automatic memory management

Example Protection:

let arr = [1, 2, 3];
let val = arr[-1];  // Caught: negative index
let val2 = arr[100]; // Caught: index out of bounds

Attack Vector: Exploiting type system weaknesses to access invalid memory

Mitigation: Strong type safety and validation

• Compile-time type checking
• Runtime type validation
• Field access validation
• Generic type constraints

Attack Vector: Code that causes infinite compilation or excessive resource usage

Mitigation: Comprehensive DoS protection

• Phase timeouts prevent infinite compilation
• Memory limits prevent memory exhaustion
• Iteration limits prevent infinite loops in type checking
• Recursion depth limits prevent stack overflow

The Script compiler includes comprehensive security tests:

# Run all security tests
cargo test security

# Run resource limit tests specifically
cargo test resource_limits_test

# Run DoS protection tests
cargo test test_dos_attack_simulation

For additional security validation, consider fuzzing the compiler:

# Install cargo-fuzz
cargo install cargo-fuzz

# Run parser fuzzing
cargo fuzz run parser_fuzz

# Run type inference fuzzing  
cargo fuzz run inference_fuzz

Regular security audits should include:

• Resource limit effectiveness testing
• Memory safety verification
• Attack vector analysis
• Dependency security scanning

If you discover a security vulnerability in the Script language:

1. Do not create a public issue
2. Email security reports to: [security@script-lang.org]
3. Include detailed reproduction steps
4. Allow time for investigation and patching

Security updates will be:

• Released immediately for critical vulnerabilities
• Clearly marked in release notes
• Documented with mitigation strategies
• Backwards compatible when possible

Script follows these security guidelines:

• OWASP Secure Coding Practices
• SANS Top 25 Software Errors prevention
• CWE (Common Weakness Enumeration) mitigation

The Script compiler is designed to support:

• SOC 2 compliance requirements
• Security auditing and logging
• Reproducible builds
• Supply chain security

let limits = ResourceLimits::custom()
    .max_iterations(1_000)              // Very restrictive
    .phase_timeout(Duration::from_secs(5))    // Short timeout
    .total_timeout(Duration::from_secs(15))   // Total limit
    .max_memory_bytes(10 * 1024 * 1024)      // 10MB only
    .max_recursion_depth(50)                  // Shallow recursion
    .max_specializations(100)                 // Limited generics
    .build()?;

let context = CompilationContext::with_resource_limits(limits);

let limits = ResourceLimits::production(); // Secure defaults
let context = CompilationContext::with_resource_limits(limits);

let limits = ResourceLimits::development(); // More permissive
let context = CompilationContext::for_development();

let stats = resource_monitor.get_stats();
println!("Compilation time: {:?}", stats.compilation_time);
println!("Memory usage: {} bytes", stats.memory_usage);
println!("Type variables: {}", stats.type_variable_count);

// Security violations are automatically logged
match context.compile_file(&path) {
    Err(Error::SecurityViolation(msg)) => {
        log::warn!("Security violation detected: {}", msg);
        // Alert security team
    }
    Ok(module) => { /* Success */ }
    Err(other) => { /* Handle other errors */ }
}

The Script language provides comprehensive security features designed to protect against common attack vectors while maintaining usability and performance. By following the guidelines in this document and leveraging the built-in security features, developers can build secure applications with confidence.

For the latest security updates and announcements, monitor the Script language security advisories and keep your installation up to date.