Phishing Api Keys in Echo Go with Api Keys

Echo Go is a lightweight HTTP framework often chosen for its simplicity and minimal runtime dependencies. When developers store and reference API keys directly in Echo Go handlers or configuration files, they create a phishing surface that attackers can exploit. The combination of predictable key names, insecure logging, and verbose error messages can inadvertently expose sensitive credentials during normal request handling.

In a typical Echo Go route, API keys may be read from environment variables and passed to downstream services. If the application echoes request data—including headers or query parameters—into logs or responses without sanitization, an authenticated or unauthenticated attacker can phish for keys through crafted inputs. For example, an attacker might send a request with a custom header such as X-API-Key: test_key and observe whether the application logs or reflects the value, confirming the presence and format of valid keys.

SSRF and insecure consumption patterns common in Echo Go services can further amplify the risk. An endpoint that forwards user-supplied URLs to external services might inadvertently trigger outbound requests that include API keys in query strings or headers. Those requests can be observed or intercepted, enabling credential harvesting. Additionally, if the service uses middleware that logs every request header indiscriminately, keys embedded in headers like Authorization: Bearer {key} may be stored in plaintext logs, making them easy targets for phishing campaigns or log scraping attacks.

Another vector involves error handling. Echo Go applications that return detailed stack traces or configuration details when a request fails can disclose which API keys were attempted and how they were processed. This information allows attackers to refine phishing lures, such as sending malicious configuration snippets or fake credential prompts that trick developers into revealing keys through logs, support channels, or shared configuration files.

Because middleBrick scans API endpoints without authentication, it can detect whether API keys appear in responses, logs, or error payloads during an unauthenticated security check. This helps identify inadvertent exposure that could facilitate phishing. The LLM/AI Security checks specifically look for system prompt leakage and output patterns that may indicate key disclosure, adding coverage for AI-assisted integrations that might process or echo sensitive values.

Remediation focuses on preventing keys from appearing in logs, responses, and error paths, and ensuring they are handled only in secure contexts. Below are concrete code examples for a secure Echo Go setup.

First, configure environment variables securely and avoid printing them. Use os.Getenv to read keys at startup and store them in memory without logging.

// main.go
package main

import (
    "os"
    "strings"

    "github.com/labstack/echo/v4"
    "github.com/labstack/echo/v4/middleware"
)

func main() {
    apiKey := os.Getenv("UPSTREAM_API_KEY")
    if apiKey == "" {
        panic("UPSTREAM_API_KEY is required")
    }

    e := echo.New()

    // Disable detailed error messages in production
    e.HideBanner = true
    e.HidePort = true

    // Secure middleware
    e.Use(middleware.RequestID())
    e.Use(middleware.LoggerWithConfig(middleware.LoggerConfig{
        Format: "${status} ${method} ${path}\n",
        // Exclude sensitive headers from logs
        HeaderExclude: []string{"Authorization", "X-API-Key"},
    }))
    e.Use(middleware.RecoverWithConfig(middleware.RecoverConfig{
        // Avoid exposing internal configuration in error responses
        EnableStackTrace: false,
    }))

    e.GET("/proxy", func(c echo.Context) error {
        req, err := c.NewRequest(c.Request().Context(), c.Request().Method, c.Request().URL.String())
        if err != nil {
            return c.JSON(500, map[string]string{"error": "invalid request"})
        }
        // Do not forward API keys in query or header by default; inject as needed
        req.Header.Set("X-Internal-Key", apiKey)
        // Use a secure HTTP client with timeouts and no redirect leakage
        resp, err := http.DefaultClient.Do(req)
        if err != nil {
            return c.JSON(502, map[string]string{"error": "upstream error"})
        }
        defer resp.Body.Close()
        return c.Response().WriteHeader(resp.StatusCode).CopyBody(resp.Body)
    })

    e.Start(":8080")
}

Second, sanitize any user input that might be reflected in logs or responses to prevent accidental key echoing. Never concatenate headers directly into log lines or response bodies.

// sanitize.go
package main

import (
    "net/http"
    "strings"

    "github.com/labstack/echo/v4"
)

func sanitizeHeader(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        // Remove or mask keys from incoming request headers before processing
        if key := c.Request().Header.Get("X-API-Key"); key != "" {
            // Avoid logging raw key; replace with a placeholder if needed for tracing
            c.Request().Header.Set("X-API-Key", "[REDACTED]")
        }
        return next(c)
    }
}

Third, ensure that outbound requests from Echo Go services do not leak keys in URLs or query parameters. Use structured headers and avoid constructing URLs with keys as query strings.

// outbound.go
package main

import (
    "net/http"
)

func makeOutboundRequest(ctx *http.Request, key string) (*http.Response, error) {
    req, err := http.NewRequestWithContext(ctx.Context(), ctx.Method, ctx.URL.String(), ctx.Body)
    if err != nil {
        return nil, err
    }
    // Set key only in secure header, not in URL
    req.Header.Set("Authorization", "Bearer "+key)
    // Disable automatic redirect handling to prevent key leakage via Referer
    req.Close = true
    client := &http.Client{
        CheckRedirect: func(req *http.Request, via []*http.Request) error {
            return http.ErrUseLastResponse
        },
    }
    return client.Do(req)
}

Finally, integrate middleBrick into your workflow to continuously validate that keys are not exposed. Use the CLI to scan endpoints and verify that no keys appear in responses or error payloads. The Pro plan enables continuous monitoring and CI/CD integration, so any regression that risks key exposure can fail builds before deployment.