As part of general security hardening of an AEM instance, Adobe recommends turning off the debug filter in Production Publish instances as part of the OSGi configurations (http://dev.day.com/docs/en/cq/current/deploying/security_checklist.html#OSGI Settings).
However, it seems that this configuration is no longer found in the OSGi configurations in AEM 5.6.1. It’s back in AEM 6.0 and from what I’ve heard this may be addressed in a future release of AEM 5.6.x.
But for those currently on 5.6.1, how can you change a configuration that does not exist and prevent debug output being enabled? By either stopping the com.day.cq.wcm.core.impl.WCMDebugFilter component under http://localhost:4502/system/console/components, or by curl:
curl -u admin:admin -d "action=disable" http://localhost:4503/system/console/components/com.day.cq.wcm.core.impl.WCMDebugFilter