Token Leakage in Aspnet with Dynamodb

Token leakage in an ASP.NET application that uses Amazon DynamoDB typically occurs when authentication or session tokens are handled insecurely in code that reads from or writes to DynamoDB. For example, storing unencrypted access tokens or session identifiers in a DynamoDB table without proper access controls can expose sensitive data if the table’s permissions are misconfigured or if an attacker exploits an injection flaw to retrieve items.

DynamoDB’s integration with ASP.NET often involves the AWS SDK for .NET. If the application caches tokens in DynamoDB for background processing or session management, and the SDK calls are not properly secured, tokens may be exposed through logs, error messages, or insufficient IAM policies. A common pattern is to store a user’s bearer token in a DynamoDB item to allow token refresh or revocation; if the table lacks fine-grained IAM conditions, an attacker who compromises one user’s credentials might enumerate or modify other users’ tokens via over-permissive read/write permissions.

Another vector arises from DynamoDB Streams and AWS Lambda triggers in an ASP.NET backend. If a stream is configured to emit token-containing items to a Lambda function that does not validate input, an attacker might leverage SSRF or event injection to intercept tokens. Additionally, if the ASP.NET app uses unauthenticated endpoints that interact with DynamoDB—such as health checks or status endpoints that query token metadata—LLM/AI security checks may flag these as unauthenticated LLM endpoint risks when token-handling logic is exposed without authentication.

Real-world attack patterns include injection attempts that exploit malformed input to access DynamoDB items (BOLA/IDOR), leading to token exposure, and privilege escalation through BFLA if IAM policies allow broader read access than intended. Findings from a middleBrick scan can surface these risks by correlating authentication checks, BOLA/IDOR tests, and DynamoDB-specific configuration analysis, mapping findings to frameworks like OWASP API Top 10 and PCI-DSS.

When scanning an ASP.NET API that uses DynamoDB, tools like middleBrick can detect token leakage risks by testing unauthenticated surfaces, validating input handling against DynamoDB query patterns, and checking whether tokens are stored or transmitted without adequate encryption or authorization. The scan’s per-category breakdown helps prioritize remediation, ensuring that token-handling logic aligns with compliance requirements.

To remediate token leakage in ASP.NET when using DynamoDB, implement strict access controls, encrypt sensitive fields, and validate all inputs. Use the AWS SDK for .NET with least-privilege IAM roles and avoid storing raw tokens; instead, store token hashes or use short-lived tokens with secure refresh mechanisms.

Example: Secure DynamoDB table setup and token storage

Define a DynamoDB table with server-side encryption and fine-grained access policies. In your ASP.NET configuration, ensure the SDK uses IAM roles that restrict actions to specific table resources and attributes.

// Example: Configure AWS SDK in ASP.NET with restricted permissions
var awsOptions = new AWSOptions
{
    Region = RegionEndpoint.USEast1,
    Credentials = new StoredProfileAWSCredentials("MyProfile")
};
services.AddAWSService<IAmazonDynamoDB>(awsOptions);

When storing token metadata, use conditional writes and avoid placing raw tokens in DynamoDB. If tokens must be stored, encrypt them using AWS KMS and store only the ciphertext.

// Example: Store token metadata with encryption and minimal attributes
var request = new PutItemRequest
{
    TableName = "UserTokens",
    Item = new Dictionary<string, AttributeValue>
    {
        { "UserId", new AttributeValue { S = user.Id } },
        { "TokenHash", new AttributeValue { S = ComputeSha256(token) } },
        { "ExpiresAt", new AttributeValue { N = DateTime.UtcNow.AddHours(1).ToString("o") } },
        { "EncryptedData", new AttributeValue { B = EncryptWithKms(token, "alias/my-key") } }
    },
    ConditionExpression = "attribute_not_exists(UserId)"
};
await dynamoClient.PutItemAsync(request);

Implement input validation and parameterized queries to prevent injection and BOLA/IDOR. Use DynamoDB’s conditional expressions and ensure that access patterns enforce ownership checks.

// Example: Retrieve token metadata with ownership validation
var request = new GetItemRequest
{
    TableName = "UserTokens",
    Key = new Dictionary<string, AttributeValue>
    {
        { "UserId", new AttributeValue { S = currentUserId } }
    },
    ConsistentRead = true
};
var response = await dynamoClient.GetItemAsync(request);
if (!response.IsItemSet) throw new UnauthorizedAccessException();

For DynamoDB Streams and Lambda triggers, validate event sources and restrict permissions. Ensure the Lambda function’s execution role only has read access to the specific stream and uses secure deserialization.

// Example: Lambda handler with strict event source validation
public async Task FunctionHandler(DynamodbEvent evnt, ILambdaContext context)
{
    foreach (var record in evnt.Records)
    {
        if (record.eventSource != "aws:dynamodb") continue;
        var image = record.dynamodb.Keys; // Validate keys before use
        // Process token metadata securely
    }
}

Enable logging and monitoring for anomalous access patterns, and rotate KMS keys regularly. Combine these practices with middleBrick’s continuous monitoring (Pro plan) to detect configuration drift and ensure tokens remain protected across scans.