Missing Input Validation and Sanitization

[gtema]

VULNERABLE PATTERNS:

struct CreateUserRequest {
    name: String,  // No length limit or character validation
    description: Option<String>,  // No sanitization
    email: String,  // No format validation
}

ATTACK VECTOR:

• Submit extremely long strings (memory exhaustion)
• Inject SQL metacharacters if raw queries used
• LDAP injection via special characters (* & | !)
• Command injection if input used in system calls
• Log injection via newlines and control characters
• Unicode normalization attacks

IMPACT:

• Database injection leading to data breach
• Log tampering and audit trail corruption
• Resource exhaustion from oversized inputs
• Cross-site scripting if reflected in web UI
• Command execution in misconfigured systems

REMEDIATION:

use validator::{Validate, ValidationError};

#[derive(Deserialize, Validate)]
struct CreateUserRequest {
    #[validate(length(min = 1, max = 255))]
    #[validate(regex(path = "USERNAME_REGEX"))]
    name: String,
    
    #[validate(length(max = 1000))]
    description: Option<String>,
    
    #[validate(email)]
    #[validate(length(max = 255))]
    email: String,
}

lazy_static! {
    static ref USERNAME_REGEX: Regex = 
        Regex::new(r"^[a-zA-Z0-9_.-]+$").unwrap();
}

async fn create_user(req: CreateUserRequest) -> Result<User> {
    // Validate before processing
    req.validate()
        .map_err(|e| ErrorBadRequest(format!("Validation failed: {}", e)))?;
    
    // Additional business logic validation
    if reserved_usernames().contains(&req.name.to_lowercase()) {
        return Err(ErrorBadRequest("Username is reserved"));
    }
    
    // Proceed with validated input
    Ok(User::create(req).await?)
}