Third-Party Data Leak Rules

Third-party monitoring and analytics services can inadvertently transmit sensitive user data to external systems.

Rules:

PII MUST be filtered before sending to third-party services.
Error tracking MUST NOT receive raw user data — use BeforeSend hooks to redact.

Overview

These rules detect Go code that sends data to third-party services. Always review what data is being transmitted and ensure it complies with privacy regulations (GDPR, CCPA, etc.).

Common Vulnerable Services

Service	Risk
Airbrake	Error tracking - sensitive data may be sent
Bugsnag	Error tracking - sensitive data exposure
Sentry	Error tracking - sensitive data in breadcrumbs/events
Rollbar	Error tracking - sensitive data leaks
Honeybadger	Error tracking - sensitive data leaks
New Relic	Monitoring - sensitive data exposure
Datadog	Monitoring - sensitive data in telemetry
OpenTelemetry	Observability - sensitive data in traces/metrics
Google Analytics	Analytics - PII tracking risks
Algolia	Search API - data exfiltration risks
Segment	Analytics - PII tracking risks
BigQuery	Analytics - sensitive data in queries
ClickHouse	Database - sensitive data queries
Elasticsearch	Search engine - sensitive data in queries

Error Tracking Services — Medium

Bad:

import "github.com/getsentry/sentry-go"

sentry.CaptureException(err) // DON'T: Captures full request context

Good:

sentry.Init(sentry.ClientOptions{
    Dsn: "https://xxx@sentry.io/123",
    RequestHeaders: []string{"Accept", "User-Agent"},
    BeforeSend: func(event *sentry.Event, hint *sentry.EventHint) *sentry.Event {
        // Remove sensitive headers
        if event.Request != nil {
            delete(event.Request.Headers, "Authorization")
            delete(event.Request.Headers, "Cookie")
        }
        return event
    },
})

Analytics/Monitoring Services — Medium

Bad:

analytics.Track("user_signed_up", analytics.Properties{
    "email":   user.Email,   // DON'T: PII!
    "phone":   user.Phone,   // DON'T: PII!
    "address": user.Address, // DON'T: PII!
})

Good:

analytics.Track("user_signed_up", analytics.Properties{
    "user_id":        user.ID,          // OK: Internal identifier
    "plan":           user.Plan,        // OK: Business data
    "country":        user.CountryCode, // OK: Non-identifying
})

// Hash PII for correlation
func hashEmail(email string) string {
    h := sha256.New()
    h.Write([]byte(email))
    return hex.EncodeToString(h.Sum(nil))[:8]
}

Data Filtering Layer

type DataFilter struct {
    sensitiveFields []string
}

func NewDataFilter() *DataFilter {
    return &DataFilter{
        sensitiveFields: []string{
            "password", "token", "secret", "key", "email",
            "phone", "address", "ssn", "credit_card", "bank_account",
        },
    }
}

func (f *DataFilter) Filter(data map[string]interface{}) map[string]interface{} {
    result := make(map[string]interface{})
    for k, v := range data {
        keyLower := strings.ToLower(k)
        isSensitive := false
        for _, field := range f.sensitiveFields {
            if strings.Contains(keyLower, field) {
                isSensitive = true
                break
            }
        }
        if isSensitive {
            result[k] = "[REDACTED]"
        } else {
            result[k] = v
        }
    }
    return result
}

Review Checklist

Before integrating any third-party service:

Identify what data is being sent
Remove any PII/PHI from transmitted data
Review data residency requirements
Implement data retention policies
Set up data export logging/auditing
Configure error handling to avoid data exposure
Review terms of service for data usage
Implement user consent management
Support data deletion requests
Conduct regular data flow audits

CWE References

CWE-200: Exposure of Sensitive Information
CWE-359: Exposure of Private Personal Information
CWE-201: Information Exposure Through Sent Data

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