Command Injection in Adonisjs with Dynamodb

Command Injection occurs when an application passes unsanitized user input to a system command. In AdonisJS, this typically arises in code that uses child process helpers (e.g., exec, spawn) to run shell commands. When the application interacts with DynamoDB, the risk surface can expand if development patterns inadvertently treat DynamoDB data or metadata as safe input for shell operations.

Consider an AdonisJS service that tags or organizes DynamoDB backups using shell commands. If a developer builds a command string by concatenating user-controlled values (e.g., a table name or backup identifier) without validation or escaping, an attacker can inject additional shell commands. For example, a table name like mytable; cat /etc/passwd could lead to unintended file reads when the command is executed. DynamoDB itself does not execute shell commands, but the surrounding application logic that references DynamoDB resources can be abused if inputs are not strictly controlled.

Another scenario involves AWS CLI calls constructed in AdonisJS to manage DynamoDB streams or exports. If the application builds CLI commands using unescaped user input (e.g., table names or key conditions), special characters can break argument boundaries and allow command chaining. Attackers may attempt to read sensitive configuration stored in environment variables or invoke local binaries. Because DynamoDB operations often require precise naming of tables and keys, developers might be tempted to interpolate strings directly, increasing the likelihood of insecure patterns.

Even though DynamoDB is a managed NoSQL service and does not have a shell, the combination of AdonisJS process execution and DynamoDB resource identifiers can create an indirect injection path. The vulnerability is not in DynamoDB, but in how AdonisJS code handles data that references DynamoDB resources. Proper input validation, strict allowlists for identifiers, and avoiding shell command construction altogether mitigate these risks.

Secure handling of DynamoDB-related inputs in AdonisJS requires strict validation, parameterized commands, and avoidance of shell injection primitives. Below are concrete patterns and code examples to prevent command injection when working with DynamoDB.

1. Validate and allowlist table and key names

DynamoDB table names and key attribute values should be validated against an allowlist or strict regex. Table names must match ^[a-zA-Z0-9_.-]+$ and should not contain shell metacharacters. Never directly interpolate user input into command strings.

import { schema } from '@ioc:Adonis/Core/Validator'

const tableNameSchema = schema.create({
  table_name: schema.string({}, [
    (rules) => rules.regex(/^[a-zA-Z0-9_.-]+$/)
  ])
})

export const validateTableName = async (input: any) => {
  await validator.validate({ schema: tableNameSchema, data: { table_name: input } })
  return input
}

2. Use AWS SDK operations instead of shell commands

Interact with DynamoDB exclusively through the AWS SDK for JavaScript/TypeScript. This eliminates shell injection risks entirely. Below is an example of safely retrieving an item by key using the official SDK.

import { DynamoDBClient, GetItemCommand } from "@aws-sdk/client-dynamodb";

const client = new DynamoDBClient({ region: "us-east-1" });

export async function getItemSafely(tableName: string, key: any) {
  // Validate tableName before use (see validation example above)
  const command = new GetItemCommand({
    TableName: tableName,
    Key: key
  });
  const response = await client.send(command);
  return response.Item;
}

3. Avoid child processes for AWS operations

Do not use exec or spawn to run AWS CLI commands. If you must execute shell commands for non-DynamoDB tasks, use parameterized APIs and strict input sanitization. For DynamoDB, the SDK is the correct tool.

// Unsafe pattern — do not use
import { exec } from 'child_process';
exec(`aws dynamodb get-item --table-name ${userSuppliedTableName}`, (err, stdout) => { ... });

// Safe pattern — use SDK as shown above

4. Escape or reject special characters if shell usage is unavoidable

In rare cases where shell interaction is required (not recommended for DynamoDB operations), escape inputs rigorously. However, prefer SDK-based approaches to avoid these complexities entirely.

5. Enforce least privilege IAM policies

Ensure the IAM role associated with your AdonisJS application has minimal permissions for DynamoDB actions. Use conditions to restrict resource-level access to specific table names, reducing the impact of any potential misconfiguration.