Sensitive Data in Logs
Overview
Logging sensitive information creates secondary exposure risks:
- Log files are often stored less securely than databases
- Log aggregation services (ELK, Splunk) may have broader access
- Logs may be shipped to third parties (monitoring vendors)
- Compliance violations: PCI-DSS (card data), GDPR (PII), HIPAA (health data)
Sensitive data that must not be logged:
- Passwords, PINs, secrets
- Credit card numbers, CVV
- Authentication tokens, session IDs
- Social Security Numbers, health data
Remediation
- Use structured logging and explicitly list safe fields
- Implement a log sanitizer/redactor middleware
- Never log request bodies wholesale — extract only safe fields
- Use
[REDACTED]placeholders for sensitive fields