Command Injection in Strapi with Dynamodb

Command injection can occur in a Strapi application using DynamoDB when untrusted input is passed to system-level operations or to auxiliary services called from Strapi logic. DynamoDB itself is a managed NoSQL service and does not execute shell commands, but Strapi code that builds shell commands or invokes external processes with user-controlled data can lead to injection. For example, if a Strapi custom controller or lifecycle hook uses environment variables, instance metadata, or external lookup values to construct shell commands (e.g., using child_process.exec or spawn), and those values include unsanitized input, an attacker can inject additional commands.

Consider a scenario where Strapi queries DynamoDB based on a user-supplied `TableName` or `KeyConditionExpression` that is later used in a shell command for automation or debugging. If the application uses concatenation to build commands like aws dynamodb get-item --table-name ${userInput}, an attacker could provide a value such as mytable; cat /etc/passwd to execute arbitrary commands on the host. This typically arises when Strapi integrates with AWS CLI or SDKs in a way that mixes DynamoDB data operations with shell interactions.

Additionally, misconfigured IAM permissions or exposed instance metadata endpoints can amplify the impact. If Strapi runs on an EC2 instance with an overprivileged IAM role, a successful command injection could allow an attacker to leverage the AWS CLI to call DynamoDB with elevated permissions, exfiltrating or modifying data. The risk is not in DynamoDB itself but in how Strapi invokes external processes or services using uncontrolled input. Therefore, validating and sanitizing any data that reaches shell commands, using parameterized SDK calls, and minimizing IAM permissions are essential mitigations.

To prevent command injection when using DynamoDB in Strapi, avoid constructing shell commands with user input. Instead, rely on the AWS SDK for JavaScript to interact with DynamoDB using structured, parameterized calls. Below are concrete, safe examples using the official AWS SDK for DynamoDB operations within Strapi controllers or services.

Use parameterized SDK methods rather than shell commands. For example, to get an item from a DynamoDB table, use the GetItemCommand with explicit table name and key fields:

const { DynamoDBClient, GetItemCommand } = require("@aws-sdk/client-dynamodb");
const client = new DynamoDBClient({ region: "us-east-1" });

const getItemSafe = async (tableName, key) => {
  const params = {
    TableName: tableName, // Ensure tableName is validated against a whitelist
    Key: key // key should be a properly typed object, e.g., { id: { S: "123" } }
  };
  const command = new GetItemCommand(params);
  return await client.send(command);
};

For querying with conditions, use QueryCommand or ScanCommand with explicit attribute values. Do not allow raw expression strings from users. Instead, map user inputs to predefined field names and value placeholders:

const { DynamoDBClient, QueryCommand } = require("@aws-sdk/client-dynamodb");
const client = new DynamoDBClient({ region: "us-east-1" });

const queryItemsSafe = async (tableName, partitionKey, partitionValue) => {
  const params = {
    TableName: tableName, // Validate tableName
    KeyConditionExpression: "pk = :pkval",
    ExpressionAttributeValues: {
      ":pkval": { S: partitionValue } // Ensure proper typing
    }
  };
  const command = new QueryCommand(params);
  return await client.send(command);
};

If you must accept table names from users, validate them against a strict allowlist to prevent misuse:

const allowedTables = ["users", "orders", "products"];
const isValidTable = (name) => allowedTables.includes(name);

if (!isValidTable(userSuppliedTable)) {
  throw new Error("Invalid table name");
}

In Strapi, implement these patterns in controllers or services, ensuring that any data used in AWS SDK calls is typed and validated. Avoid logging raw user input that might be used in debugging commands, and ensure IAM roles assigned to the runtime environment follow least privilege to limit the impact of any potential injection.