Information Disclosure in Echo Go with Api Keys

Information Disclosure occurs when an API unintentionally exposes sensitive data, such as API keys, to unauthorized parties. In Echo Go, this often arises when API keys are embedded in request headers or query parameters and are inadvertently returned in responses, logged in plaintext, or exposed through verbose error messages. Because Echo Go is commonly used to build high-performance HTTP services, developers may inadvertently create endpoints that reflect the API key in JSON payloads or headers when integrating authentication logic.

The risk is amplified when endpoints do not properly validate authorization context before returning data. For example, an endpoint that accepts an API key in the X-API-Key header and uses it to fetch user-specific data might, due to a coding oversight, include the same key in a debug response or in a redirect to an external service. This becomes an information disclosure vector because an attacker who can observe or intercept the response can harvest valid API keys.

Echo Go applications that expose OpenAPI specifications without redaction can compound the issue. If the spec references example values containing placeholder API keys and those examples are served in error responses or interactive documentation, the keys may be exposed to anyone who can view the spec. This aligns with the Data Exposure check in middleBrick, which scans for sensitive data such as API keys in responses and provides findings with severity and remediation guidance.

Additionally, if an Echo Go service uses unauthenticated endpoints to serve configuration or introspection data, an attacker may probe these paths to retrieve API keys that were intended for internal use only. This is one of the scenarios covered by middleBrick’s unauthenticated attack surface testing, ensuring that such endpoints do not leak credentials.

When API keys are logged for debugging purposes without masking or redaction, sensitive values can appear in log files that may be accessible to less-privileged users or through log aggregation systems. Proper handling requires scrubbing key values before logging and ensuring that responses do not include raw keys, especially in development or error modes.

middleBrick’s LLM/AI Security checks also highlight risks where API keys might be exposed through model outputs or prompts, particularly if the service integrates AI components that echo user-supplied data. Although Echo Go is not an AI framework, integrations that involve external AI services must ensure that API keys are not concatenated into prompts or returned in model-generated text.

By scanning an Echo Go endpoint with middleBrick, teams can detect whether API keys appear in responses, error messages, or documentation, and receive prioritized findings with severity levels and specific remediation steps. This helps prevent credential leakage before attackers can exploit exposed keys.

To remediate information disclosure involving API keys in Echo Go, apply the following patterns consistently across your service codebase. The goal is to ensure API keys are used for authentication only and are never reflected back to the client or logged in raw form.

1. Avoid echoing API keys in responses

Never include the API key value in JSON or text responses. Instead, use a constant or placeholder when acknowledgments are necessary.

package main

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

func main() {
    e := echo.New()
    e.GET("/resource", func(c echo.Context) error {
        apiKey := c.Request().Header.Get("X-API-Key")
        if apiKey == "" {
            return echo.NewHTTPError(http.StatusUnauthorized, "missing API key")
        }
        // Validate apiKey against a secure store, then proceed
        // Do NOT include apiKey in the response
        return c.JSON(http.StatusOK, map[string]string{
            "status": "ok",
            // Never include: "api_key": apiKey
        })
    })
    e.Start(":8080")
}

2. Mask API keys in logs

When logging requests that contain API keys, replace the actual key with a masked version to prevent exposure in log storage.

import (
    "log"
    "strings"
)

func logRequestWithMaskedAPIKey(header string) {
    key := header // assume extracted safely
    masked := "****"
    if len(key) > 4 {
        masked = key[:2] + "****" + key[len(key)-2:]
    }
    log.Printf("Request with API key: %s", masked)
}

3. Use secure configuration for example values

When generating OpenAPI specs, ensure that examples do not contain real API keys. Use placeholder values that cannot be mistaken for real credentials.

components:
  parameters:
    ApiKeyParam:
      name: X-API-Key
      in: header
      required: true
      schema:
        type: string
      example: "your-api-key-here" # non-sensitive placeholder

4. Restrict error detail exposure

Configure Echo to return generic error messages in production to prevent leaking stack traces or internal details that might reference API keys.

e := echo.New()
e.HidePort = true
 e.Debug = false // disable debug mode in production

5. Validate and scope API key usage

Ensure that API keys are validated against an access control list and that their scope is limited to the minimum required endpoints.

func validateKey(key string) bool {
    // Compare against a secure store or environment variable
    return key == "${EXPECTED_API_KEY}"
}

By implementing these practices, Echo Go services reduce the risk of information disclosure related to API keys and align with security checks provided by tools like middleBrick.