Go Security

Go Security

Dependency Management

• Use Go modules for all dependency management
• The go.sum checksum database provides assurance against module mutation
• Pin dependency versions, including transitive modules
• Run govulncheck regularly to scan for known vulnerabilities in dependencies

Input Validation

• Validate all user input using Go native packages (strconv, regexp) or third-party validators like go-playground/validator
• Never trust input from external sources without validation

XSS Prevention

Use html/template (not text/template) for rendering HTML. It applies contextual autoescaping for HTML, CSS, JavaScript, and URL contexts.

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name := r.FormValue("name")
tmpl := template.Must(template.ParseGlob("page.html"))
data["Name"] = name
err := tmpl.ExecuteTemplate(w, "page", data)

Use nosurf for CSRF prevention in HTTP handlers.

SQL Injection Prevention

Use parameterized queries. In Go, statements are prepared on the DB, not the connection:

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customerName := r.URL.Query().Get("name")
db.Exec("UPDATE creditcards SET name=? WHERE customerId=?", customerName, 233)

When using db.Query() with string formatting, sanitize all input first.

Cryptography

• Use Go's standard crypto and golang.org/x/crypto packages
• Do not implement custom cryptographic algorithms
• Use well-established algorithms (AES-GCM, ChaCha20-Poly1305, Ed25519)

HTTPS and TLS

Enforce HTTPS with HSTS headers and explicit TLS server configuration:

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w.Header().Add("Strict-Transport-Security", "max-age=63072000; includeSubDomains")

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config := &tls.Config{ServerName: "yourServiceName"}

Always encrypt in-transit communication, even for internal services.

unsafe and cgo

unsafe Package

• The unsafe package bypasses Go's type system; subtle mistakes are common
• Avoid unsafe unless there is no alternative (low-level system calls, performance-critical FFI)
• Verify safe usage with Go's vet tooling

cgo

Avoid cgo when possible. Known issues:

• Breaks Go's cross-compilation
• Increases binary size and reduces portability
• cgo calls are significantly slower than native Go calls
• Puts Go's concurrency model at risk
• May break static binary linking

Error Handling and Logging

• Handle every error explicitly (if err != nil)
• Never log secrets, tokens, API keys, or PII
• Sanitize data before including it in log output
• Do not expose internal error details in user-facing responses

nil Pointer Safety

When unmarshalling JSON into structs with pointer fields, unset pointers remain nil. Dereferencing them causes a panic:

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type Foo struct {
    Bar *Bar
}

var f Foo
json.Unmarshal([]byte(`{"other":"data"}`), &f)
// f.Bar is nil -- accessing f.Bar.Field will panic

Always check pointer fields for nil before dereferencing.

Tooling

Implementation Checklist

• Go modules are used with go.sum integrity checking
• govulncheck runs in CI
• All user input is validated before use
• html/template is used for HTML rendering (not text/template)
• SQL queries use parameterized statements
• Standard crypto packages are used (no custom crypto)
• HSTS is set and TLS is configured with explicit ServerName
• unsafe and cgo usage is justified, minimized, and reviewed
• Errors are handled explicitly; no secrets in logs or error responses
• Pointer fields are checked for nil before dereferencing

References

• Go Modules Reference
• govulncheck
• OWASP Go Secure Coding Practices
• Snyk: Go Security Cheatsheet