Api Key Exposure in Echo Go with Dynamodb

When building HTTP services in Go using the Echo framework, developers often store configuration such as database credentials or external API keys in AWS DynamoDB. If application code or build-time tooling retrieves these items and inadvertently logs, serializes, or returns them, an Api Key Exposure can occur. This specific combination—Echo Go service + DynamoDB as the configuration store—creates risk when secrets are handled without strict access controls and are exposed through endpoints, logs, or error messages.

DynamoDB itself does not leak keys; the exposure typically arises from how an Echo Go application reads items (e.g., using the AWS SDK for Go v2), caches them in memory, and serves them through HTTP routes. For example, an endpoint intended for internal diagnostics might return configuration sections, including the DynamoDB item containing an API key. If that endpoint is publicly reachable or lacks proper authentication, an attacker can harvest the key. Additionally, if the Go application logs the retrieved item with its value intact, and those logs are aggregated centrally, the key is effectively exposed to anyone with log access.

The AWS SDK for Go v2 makes calls to DynamoDB via operations such as GetItem or Query. If the application code does not filter sensitive attributes before constructing responses, the full item—including string-valued keys—can be included in JSON rendered by Echo Go routes. This becomes especially problematic when CORS is misconfigured or when debugging routes are left enabled in production, a common misstep when using DynamoDB as a configuration backend.

Another vector specific to this stack involves environment-based item retrieval where the Echo Go service uses IAM roles or keys with overly broad dynamodb:GetItem permissions. If the service is compromised, the attacker can use the same permissions to read sensitive items directly from DynamoDB, effectively extracting the embedded API key. The exposure is then not just an Echo Go logging issue, but also an authorization issue where IAM policies attached to the service allow reading secrets that should be restricted to specific principals or conditions.

Consider a scenario where an Echo Go handler fetches a configuration item from DynamoDB and returns it to the client. If the handler does not redact the key field, the response becomes a direct leak. Real-world findings from scans using methodology aligned with the OWASP API Top 10 have shown such patterns, where unchecked data exposure occurs because the application trusts its own internal flow without validating what is returned to the caller. This maps to the BOLA/IDOR category when different authenticated contexts can retrieve items they should not, and to Data Exposure when the key value travels unencrypted in application responses.

Remediation focuses on three areas: controlling what DynamoDB returns, preventing Echo Go from exposing sensitive fields, and tightening IAM usage. Below are concrete, idiomatic Go examples using the AWS SDK for Go v2 and Echo that implement these controls.

1. Retrieve only necessary attributes and redact sensitive fields

Use ProjectionExpression to fetch only non-sensitive configuration properties, and explicitly remove key material before constructing an HTTP response.

// config.go
package config

import (
    "context"
    "github.com/aws/aws-sdk-go-v2/aws"
    "github.com/aws/aws-sdk-go-v2/service/dynamodb"
    "github.com/aws/aws-sdk-go-v2/service/dynamodb/types"
    "github.com/labstack/echo/v4"
)

type ConfigService struct {
    client *dynamodb.Client
    tableName string
}

func NewConfigService(client *dynamodb.Client, tableName string) *ConfigService {
    return &ConfigService{client: client, tableName: tableName}
}

// GetPublicConfig retrieves only safe fields and redacts secret keys.
func (s *ConfigService) GetPublicConfig(ctx context.Context) (map[string]interface{}, error) {
    out, err := s.client.GetItem(ctx, &dynamodb.GetItemInput{
        TableName: aws.String(s.tableName),
        Key: map[string]types.AttributeValue{
            "config_id": &types.AttributeValueMemberS{Value: "app-config"},
        },
        // Request only non-sensitive attributes
        ProjectionExpression: aws.String("feature_flag,timeout_ms,region"),
    })
    if err != nil {
        return nil, err
    }

    result := make(map[string]interface{})
    for k, v := range out.Item {
        // Explicitly exclude known sensitive attributes
        if k == "api_key" || k == "secret" {
            continue
        }
        if sv, ok := v.(*types.AttributeValueMemberS); ok {
            result[k] = sv.Value
        }
    }
    return result, nil
}

2. Secure Echo Go route with authentication and field filtering

Ensure the route requiring configuration is protected and does not echo back sensitive fields.

// main.go
package main

import (
    "net/http"
    "github.com/labstack/echo/v4"
    "github.com/labstack/echo/v4/middleware"
)

func main() {
    e := echo.New()
    e.Use(middleware.JWTWithConfig(middleware.JWTConfig{
        SigningKey: []byte("your-secret-key"),
    }))

    // Assume configService is initialized elsewhere
    e.GET("/config/public", func(c echo.Context) error {
        cfg, err := configService.GetPublicConfig(c.Request().Context())
        if err != nil {
            return c.JSON(http.StatusInternalServerError, map[string]string{"error": "unable to load config"})
        }
        return c.JSON(http.StatusOK, cfg)
    })

    e.Logger.Fatal(e.Start(":8080"))
}

3. Apply least-privilege IAM and use DynamoDB conditions

While not Go code, the IAM policy for the service should restrict actions to specific table resources and include conditions that block retrieval of sensitive attributes when possible. For example, scope down to dynamodb:GetItem on non-secret items and avoid wildcard permissions.

4. Avoid logging sensitive values

Ensure structured logging in Echo Go does not include configuration values.

// bad: logs may contain keys
// logger.Infof("Loaded config: %+v", item)

// good: log only metadata
logger.Infof("Config loaded with feature_flag=%s, timeout=%d", featureFlag, timeoutMs)