Go Secure Coding Best Practices

Go, popularly known as Golang, is a statically typed, compiled language known for its simplicity, efficiency, and strong support for concurrent programming. But, like every language, writing secure code in Go requires diligence and awareness. This blog post will guide you through some of the best practices for secure coding in Go, supplemented with examples.

Secure coding practices are essential for protecting applications from vulnerabilities and possible security risks. This exhaustive checklist provides developers with a nuanced set of guidelines for Go, each illustrated with real-world examples. During a security code review, it's crucial for developers not only to understand but also to consistently implement these best practices to maintain a secure application environment.

1. Avoiding SQL Injections

When working with databases, always use prepared statements or query-building libraries that automatically escape parameters.

Bad

query := "SELECT * FROM users WHERE username='" + user + "'"

Good

query := "SELECT * FROM users WHERE username=?"
rows, err := db.Query(query, user)

2. Proper Error Handling

Always handle errors and avoid generic error messages that may include details of an unknown error. This prevents leaking internal details to potential attackers.

Bad

 if err !=nil {
    msg := fmt.Sprintf("Internal Server Error: %v", err)
    http.Error(w, msg, http.StatusInternalServerError)
    return
}

Good

if err != nil {
    log.Printf("An error occurred: %v", err)
    http.Error(w, "Internal Server Error", http.StatusInternalServerError)
    return
}

In the Good example, the details of the error are written to a private application log.  The HTTP response to the client contains a fixed message that does not reveal any internal details from the error.

3. Safe Use of External Input

Never trust external input. Always validate and sanitize inputs before using.

func IsValidInput(input string) bool {
    // Check input against a set of criteria
    return true // or false
}

if !IsValidInput(userInput) {
    http.Error(w, "Invalid input", http.StatusBadRequest)
    return
}

4. Safe Concurrency

When using goroutines, be cautious about data races. Use channels or sync primitives.

var mu sync.Mutex
counter := 0

func incrementCounter() {
    mu.Lock()
    counter++
    mu.Unlock()
}

5. Secure Random Number Generation

When generating random numbers, especially for cryptographic purposes, use the _{`crypto/rand`} package.

b := make([]byte, 10)
_, err := rand.Read(b)
if err != nil {
    log.Fatal(err)
}

6. Scan code for vulnerabilities with govulncheck

Developers can use the _govulncheck tool to determine whether any known vulnerabilities affect their code and prioritize their actions based on the affected functions and methods in use.

To sum up, Go provides a strong foundation for developing applications, but it's crucial to pay attention to the importance of security. By adhering to the best practices outlined earlier, and staying updated on application security best practices, you can achieve a dual objective: creating applications that are not only efficient but also fortified against security vulnerabilities.