Friday, November 25, 2016

Overcoming the Identity or Infrastructure Duplication to Secure Linux Instances in Public Clouds

Securing Linux instances in public (or private) clouds often requires the duplication of infrastructure (or additional overhead) just to be able to provide basic services like authentication.  Centrify just debuted a new client that leverages a capability called Identity Broker.  This allows users of Centrify privilege service to extend authenticaiton to Linux systems using Active Directory, LDAP, Google Directory and others without the need to implement extensions to AD or LDAP or any supporting infrastructure (like site-to-site VPNs).

The Challenges (AWS as an example)
In previous blog posts, we discussed the additional controls that can be implemented on top of Amazon's IAM and cryptography-based capabilities.  The model suggested the use of Active Directory and Centrify Server Suite.
Regardless of the solution, organizations need to find ways to extend this infrastructure by using these techniques:
  • Re-creation of infrastructure (e.g. standing-up Active Directory or LDAP-like infrastructure)
  • Network extension (e.g. treating the public cloud like a branch by implementing site-to-site VPNs)
  • Capability duplication (e.g. implementing software and services in AWS)
In this article we'll discuss how organizations can leverage Centrify Privilege Service and the new Linux Agent (Identity Broker) to secure Linux instances and extend Enterprise Identity out to public clouds without the need of the additional overhead.

Centrify Privilege Service
Privilege Service is Centrify's answer to the traditional "password-driven" use cases (the industry refers as Shared Account Password Management, Privilege Session Management, etc);  however unlike other solutions, there are several capabilities areas that set it apart from the traditional "Password Vault"
  • Flexible deployment:  Both as SaaS and On Premises  (in fact, it was designed as a SaaS solution first)
  • Identity Sourcing and Federation built-in (includes Identity Service, this means support for AD, LDAP, Google and others  plus simplified SAML-based federation and 3K+ ready web and mobile apps)
  • Policy, Workflow and MFA Engine:  Policies for time and geo-location, RBAC, step-up authentication and Multi-factor including Smartcard, plus a built-in access request system (+ServiceNow integration)
  • Infrastructure Extensibility:  Privilege Service can be extended to any network using a Windows-based Centrify Connector via web protocols.

New Linux Agent
The new Linux agent takes advantage of a capability called "Identity Broker" this allows the bridging of identities known to Centrify Privilege Service;  this is done via the Centrify connector.  This means that the overhead of duplicating enterprise identity infrastructure or extending the enterprise to the public network can be avoided in this particular use case;  all that is required is to deploy a Centrify connector wherever you want to extend Password-related services and Linux authentication.  Let's show an illustration.

Company X needs to provide identity-based reporting and attestation of who has access to their public cloud EC2 instances in AWS;  their primary identity source is AD.  They could have used any model (independent forest, one-way trust + site2site VPN or RODC) to extend AD to AWS  or they could have deployed Amazon IAM roles and used SSH keys; but any of these models implied additional overhead.  With CPS and Identity Broker, all they did is this:
With this model, CompanyX not only can accomodate their corporate IT users, but external entities as well.  And as we discussed before, password, session and additional services are consolidated as well, both on premises and on any public cloud.  Plus
  • No need to deploy "jumpboxes" to the private clouds (limits exposure)
  • Shared account passwords for local accounts (Linux, Windows) or databases (like Amazon RDS) can be controlled
  • Access Request provides the assurance of "documented approvals" to sensitive systems
  • Deploy MFA or access only from the OnPrem network as additional controls.

Agent Architecture
The client architecture is using UNIX frameworks like Name Service Switch (Identity) and Pluggable Authentication Modules (Auth).  It also supports offline login as well as direct or proxy-based user/password or OAUTH-based enrollment codes (very useful for automation). This client implements the CLI tookit for setting, retrieving or deleting credentials under management.

Supported Platforms
Platforms supported in the initial release - more on the way Platforms supported in the initial release - more on the way

UNIX Identity
Following on the legacy of Server Suite, the new agent generates identity like DirectControl in workstation mode.
Login - user's short name (must use the fully-qualified name the first time)
UID - auto-generated based on the GUID
Primary group - auto-private (same as UID)
GECOS - the display name in Centrify Identity Service
Home/Shell - configurable in the Settings tab.
Since most public clouds don't need legacy identity (for services like NFS), this makes the client very lightweight.

There's an implied expectation of DevOps "friendliness" when a private or public cloud solution is implemented.  The new Linux agent leverages enrollment codes for this capability.
Centrify provides a sample AWS script that can be used with enrollment codes in the User Data field or with any other framework like OpsWorks (see attachment)

Identity Broker
Privilege Service can accomodate several identities, including:
Note that it can accommodate identities from Active Directories without any trust relationships.
These identities can be aggregated using Identity Service Roles:
 Roles, in turn can be assigned the AgentAuth privilege on a Linux Resource:
IB-aws resource.png
As you can see the model works like this:
Users or groups from Identity Sources are added to CIS Roles that are granted the AgentAuth right in CPS.

Basic Commands
Agent Operation
  • cinfo – obtain information about the agent
  • cenroll – enroll the identity platform and enable features
  • cunenroll – leave the platform and optionally delete resource and any managed accounts
  • cflush – flush the local cache
IB login.PNG


  • csetaccount – add a managed account for the resource
  • cgetaccount – obtain a managed account’s password
  • cdelaccount - delete a managed account's password

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