A security service enables service providers to register available services. Prospective service consumers may register with the security service to access a particular registered service, and may specify conditions for access that are subject to approval by the corresponding service provider. Based on the registrations of the service provider and the service consumer, the security service can define access policies that may be enforced to control the conditions under which a service consumer accesses or utilizes the particular service. Additionally, changes to the access policies may be propagated to running services in near real time. Some implementations enable masking of information provided to particular service consumers based on determined needs of each service consumer for access to particular information. In some instances, the service providers may provide log information to the security service, which may be monitored to identify anomalies, security breaches or the like.