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Saturday 8 November 2014

Risk reduction through Jump Servers

A common practice in today's data centers is to allow Systems Administrators Remote Desktop  (RDP) or Secure Shell (SSH) access to the servers they are administrating, directly from their desktops.  Regardless of where they are located!

Although restricting Lateral access between servers is quite easily achieved through group policy on Windows, or source whitelisting local firewall rules for both Windows and UNIX/Linux, these are not enabled by default. Typically, even with network segmentation and access control lists, is is possible to jump from server to server unhindered, by simply having access to the appropriate credentials. 

Both the Target Breach, and the Home Depot Breach were initiated by a compromised business partner with access to internal resources.  Those accounts were used to assess the network topology and browse the corporate directories to find more privileged accounts. Once inside, these credentials could be used to log onto servers within the environment in search of information or more credentials to abuse. The attacker could, over time, hop from server to server essentially unnoticed.

Restricting Lateral Access within your Network
The concept of a "jump" server has been around for decades, but is rarely in use or enforced.  One popular use of jump servers is to restrict access into a DMZ. This allows administrative control of servers in the DMZ to be regulated and audited as per compliance rules.

In Microsoft Technet's  "Implementing Secure Administrative Hosts", they state: 
Secure administrative hosts are workstations or servers that have been configured specifically for the purposes of creating secure platforms from which privileged accounts can perform administrative tasks in Active Directory or on domain controllers, domain-joined systems, and applications running on domain-joined systems. In this case, “privileged accounts” refers not only to accounts that are members of the most privileged groups in Active Directory, but to any accounts that have been delegated rights and permissions that allow administrative tasks to be performed.

Although the “most privileged” accounts and groups should accordingly be the most stringently protected, this does not eliminate the need to protect any accounts and groups to which privileges above those of standard user accounts have been granted.

A secure administrative host can be a dedicated workstation that is used only for administrative tasks, a member server that runs the Remote Desktop Gateway server role and to which IT users connect to perform administration of destination hosts, or a server that runs the Hyper-V® role and provides a unique virtual machine for each IT user to use for their administrative tasks. In many environments, combinations of all three approaches may be implemented.

So... restrict access to servers, specifically for anyone with privileges above a basic user. 
I can't argue with that at all... 

Enter CyberArk's Next Generation Jump Server

More than just a jump server from which to initiate RDP or SSH sessions, CyberArk has added Privileged Session Management to monitor and record all access through the jump server. The tightly integrated SSH proxy is context aware, and can be configured to look for anomalous behavior.  Not only can you control "who" has access to "what" through the jump server, but you can alert on suspicious or anomalous activity within those sessions.  Both secure RDP to Windows servers, as well as SSH to UNIX/Linux/Network appliances are managed via Privileged Session Manager on the jump server.  

The jump server can now be used to isolate your server environment from  your workstation endpoints, and provide real-time visibility into administrative access.  Without adding agents to the servers being administered, you can use workflows to augment authentication and authorization, and monitor access at a granular level, recording all activities for future playback and potential audit attestation.

Integrate this service with their Enterprise Password Vault, and you have significantly reduced privilege escalation from your threat landscape.

Rogue or Malicious Administrator
Many companies, small and large alike, allow almost unrestricted access to the data center servers for administrator, both from within the local network, and over VPN. The excuse being that this is required in case of a emergency.

This excessive access allows anyone authenticated, malicious or otherwise, to jump laterally from server to server.  The Target Breach, in particular is known to have accommodated it's attackers by allowing a credentialed account in the Business Partner network to access servers in the core data center, and ultimately get on to the Point-of-Sale systems.  Restricting this lateral access by enforcing the use of jump servers would not totally remove the Rogue Administrator threat, however all access through the server would be monitored and recorded.  Any administrative commands/requests/activities that were deemed anomalous by predefined security policies could be blocked and/or alerted on.

Malware Mitigation
By allowing lateral access between servers, an infected server could act to propagate malicious code to its peers. Most Advanced Persistent Threats rely on the ability to see peer servers laterally and scan them for exploitable opportunities.  With jump servers in place, and lateral access removed through policy, malicious actors and malware alike will not be able to propagate without going through the jump server and being seen/alerted/blocked.

Pass the Hash
One of the techniques typical of a APT is the “Pass the Hash” attack, where the invader captures account logon credentials in the form of a cached password "hash" on one machine and then use them to authenticate to another machine.  This little known exposure has been around for a couple decades, but has become an industry favorite among cyber criminals.  By enforcing all server remote administration through the jump servers, this method of subversion is eliminated.

Don't be the next headline.  Choosing either CyberArk's suite of Privileged Access and Session Management tools or another Remote Access Gateway product will significantly reduce your threat landscape and allow you to sleep more easily.


CyberArk: Are You Ready to Take the Next Jump? Secure your IT Environment with Next Gen Jump Servers
Privileged Accounts at Root of Most Data Breaches
SANS: Pass-the-hash attacks: Tools and Mitigation
Microsoft: Defending Against Pass-the-Hash Attacks
CyberArk Launches Enhanced “CyberArk DNA” to Detect Pass-the-Hash Vulnerabilities
NSA: Reducing the Effectiveness of Pass-the-Hash 
The World's #1 Cyber Security Risk - Active Directory Privilege Escalation
IT World Canada: Early lessons from the Target breach
IT World Canada: Hacking of HVAC supplier led to Target breach: Report
IT World: Home Depot says attackers stole a vendor's credentials to break in
Cisco: Putting a Damper on ‘Lateral Movement’ due to Cyber-Intrusion  
Trend Micro: How Do Threat Actors Move Deeper Into Your Network? 
Prevent Lateral Movement With Local Accounts (Windows) 
Lateral Movement: No Patch for Privilege Escalation 
Intel: Achieving PCI DSS compliance when managing retail devices with Intel® vPro™ technology 
Techrepublic: Jump boxes vs. firewalls 
Microsoft: Implementing Secure Administrative Hosts 
CyberArk: Privileged Session Manager 
ITWorld Canada: The 10 Step Action Plan - Building Your Custom Defense Against Targeted Attacks and Advanced Persistent Threats

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