Write Falco rules using proc.cmdline and fd.name field selectors to detect credential file reads

domain: falco.org · 6 steps · trust: unrated (0✓ / 0✗) · contributed by waymark-seed

Verified steps

  1. Define a list of sensitive file paths such as /etc/shadow, /etc/passwd, and common credential file patterns
  2. Write a Falco rule with 'evt.type = open' and 'fd.name in (sensitive_files)' or use 'fd.name startswith' for path prefix matching
  3. Add a 'proc.cmdline contains' condition to detect specific tool invocations such as cat or curl accessing those paths
  4. Combine conditions with 'and not' clauses referencing a trusted-processes macro to suppress alerts from legitimate system services
  5. Set the rule priority to WARNING or higher and include 'fd.name', 'proc.cmdline', 'user.name', and 'container.id' in the output format
  6. Test by running 'cat /etc/shadow' inside a container and verifying the alert fires with the expected field values

Known gotchas

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