logging-security

• SKILL.mdcore · 5,472 bytes
• SKILL.mdcore · 5,472 bytes
• metadata.jsonasset · 1,273 bytes
• references/verifying-findings.mddoc · 3,877 bytes

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# Logging Security

Keep secrets and personal data out of logs at the call site rather than relying on redaction, neutralize log and field injection, record audit events that survive, and treat log read access as data access. Use when generating logger calls or structured-logging schemas, wiring log shippers, sinks, retention, and access controls, or specifying audit-logging requirements.

## ALWAYS

- Decide what is safe to log **at the call site**, and log a reference rather than a value: an id, a hash, a type, a count. A redactor is the last net, not the design — it matches field names and known patterns, so it cannot see personal data sitting inside an assembled string. A formatted notification body, a templated message, an exception with interpolated arguments: the name and the address are in the prose, in no named field, matching no pattern. Nothing downstream will catch that.
- Run a **redactor** at the sink anyway, for the cases the call site missed: credential-shaped values, `Authorization` and `Cookie` headers, query strings carrying tokens, and the personal-data patterns in `rules/redaction_patterns.json`. `secret-detection` owns which literals count as a credential; this rule is that the redactor exists and runs before anything leaves the process.
- Log in a **structured format** (JSON or logfmt) with stable field names — `timestamp`, `service`, `version`, `level`, `trace_id`, `span_id`, `request_id`, `event`, and `user_id` when there is an authenticated one. Structure is what makes redaction, retention, and access control expressible per field instead of per line.
- Neutralize user-controlled strings before they enter a log record. Line injection (CWE-117) is the classic case — a `\n` or `\r` lets an attacker forge a whole record — but structured logging moves the problem: a value that parses as JSON can inject *fields* into the ingested document, and ANSI escape sequences (`\x1b[`) are interpreted by the terminal of whoever reads the log. Encode the value; do not concatenate it into the line.
- Record security-relevant events as **immutable audit records**: authentication success and failure, MFA challenges, password and role changes, permission grants and revocations, data export, administrative action. These carry longer retention and stricter access than operational logs, and they are the reason failed logins must keep being written even when someone calls them noise.