Fix sensitive data written to a log in Koa
A password, token, cookie, or similar value is passed to a log sink. Centralised logs are widely readable inside an organisation and often retained for months - a credential that lands there is a credential that has left the application's control.
medium likely Koa CWE-532 / OWASP A09:2021
The vulnerable pattern in Koa
This finding comes from the Koa fixture in the owlwarden test suite. Logs are copied into aggregators, retained for months, and readable by anyone with access to the logging system. A credential that reaches a log has left the application's trust boundary.
The corrected handler
Log that the attempt happened, not the credential.
console.info({ event: 'login_attempt', userId })
// never: console.info({ password: ctx.request.body.password })If you are not using Koa
Log a redacted shape - an id, a boolean, a length - never the secret itself.
Check your own repository
npx owlwarden scan
npx owlwarden explain sensitive-data-loggedRuns on your machine. No account, no telemetry, no network unless you ask. In CI, SARIF uploads to code scanning and the exit code is the gate.
Other Koa checks
Rules with a tested Koa example.
- cors-permissive medium Cross-origin policy accepts any origin
- hardcoded-secret high Credential hardcoded in source
- insecure-cookie medium Cookie set without its protective attributes
- install-lifecycle-script medium Package declares an install-time script
- open-redirect medium Redirect target comes from the caller
- security-headers-missing medium Security headers are not configured
- sql-injection high SQL query built by string interpolation
- ssrf high Server fetches a URL the caller controls
- stack-trace-leak high Stack trace leaked in error response
- weak-crypto high Broken cryptographic primitive protecting a secret
sensitive-data-logged for every framework / All rules / owlwarden