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.

(Also read:  What if Target had followed a Zero Trust model?)

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.


References:

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
http://en.wikipedia.org/wiki/Pass_the_hash
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

FTP, SFTP, FTPS? What's the difference, and how the !@#$ do I secure them?

File Transfer (FTP) may be the single most insecure piece of infrastructure that any corporation has.  It's roots date back to the early 70's before encryption and transport security were of great concern. 

Many common malware attacks rely on unsecured FTP services within a company to stage and exfiltrate sensitive corporate data to unknown third parties.

There is little excuse for a company to be running vanilla FTP either inside their data center or especially over the Internet.  Secure file transfer protocols and standards have been around and fully supported SINCE THE TURN OF THE CENTURY!!!

 From the Tibco report: Understanding the Impact an FTP Data Breach Can Have on Your Business

"...what about the threat information contained on an unsecured

FTP server could pose to a business like yours? Consider a few other recent FTP

exposures:

• CardSystems, who processed credit card transactions for nearly 120,000 merchants totaling more than $18 billion annually, were essentially forced out of business after 40 million identities were exposed. Amex and Visa told CardSystems that they would no longer do business with the company.
• 54,000 records were stolen from Newcastle City Council
• An unsecured document was exposed on the New Mexico Administrative Office of the Courts FTP server; it contained names, birth dates, SSNs, home addresses and other personal information of judicial branch employees.
• The Hacker Webzine reports that Fox News had an exposed FTP connection linking out to Ziff Davis.
• The personal information of uniformed service members and their family members were exposed on an FTP server while being processed by major Department of Defense (DoD) contractor SAIC. As many as 867,000 individuals may have been affected."

 
Lets take a minute to discuss the legacy FTP system, it's derivative FTPS, and the completely different SFTP.

FTP  (Do not use this EVER!)

The FTP (File Transfer Protocol) protocol was documented in 1971 as  RFC 114 and eventually evolved into RFC 959 , the FTP standard that all systems use today. It has been the workhorse of most corporate file transfer systems in production.

All current Server Operating Systems, whether Windows, Unix, Linux, MAC, or Mainframe come with a variant of an FTP service following RFC 959.
There are VERY many FTP client applications available for each and every Desktop, Laptop, Tablet and smartphone in existence, also complaint with RFC 959.    

(Did I mention that there is no reason in this day and age to use vanilla FTP, EVER?)

FTPS

Once companies and security consultants  realized the great risk that FTP exhibits by sending corporate data "in the clear" over the network, they proposed RFC 2228 (in 1997) to protect FTP data in transit using SSL encryption.  Aside from transport encryption the service is identical to FTP.  

FTPS transport encryption comes in two flavors Implicit, and Explicit.  Implicit FTPS (Now pretty much obsolete) establishes an SSL or TLS session prior to exchanging data, over TCP ports 989(data)/990(control).  Explicit FTPS, the more common of the two, can use a single port for both encrypted and unencrypted data transfer.  The client initially establishes an unencrypted session, and if SSL/TLS is required, an AUTH TLS or AUTH SSL command is issued by the client to secure the control channel before sending credentials.

And then there's....

SFTP

Although regularly  confused with FTPS, SFTP is actually an application in the  SSH  protocol suite.  RFC4253 "The Secure Shell (SSH) Transport Layer Protocol"  defines the security model of this Secure File Transfer Protocol.   Whereas FTPS relies on SSL (X.509) Certificates with their associated PKI requirements to secure the session, SFTP uses Diffie-Hellman Key Exchange to manage an asymmetric pair of keys to secure the session. All UNIX based systems (Including MAC, Linux, and Mainframe) come with SSH preinstalled.   There are many variants available for Windows as well.

Both SFTP and FTPS are fully scriptable (ie: support automation). Either one is acceptable, depending on the application, and Operating System at hand.

Up to this point, we've discussed securing the Data Transport, or "Data in Motion", but what about securing the "Data at Rest"?  How do we secure the file transfer directory structure?

In simplest terms, strong user/group access controls are required on FTP service directory structure.  I'm going to link to some vendor recommendation sites here:

• Microsoft: How to create a security-enhanced FTP directory that uses Password Authentication
• WSFTP: Admin guide 
• Installing & Configuring VSFTPD FTP Server for Redhat Enterprise Linux, CentOS & Fedora 
• How to Make Your Mac an SFTP Server

Disable Anonymous FTP!  Sorry, but you should know who is connecting to your file server.

But, for the best level of security, 

run SFTP (ok, even FTPS) inside a chroot jail or sandbox. 

In the UNIX world (Including MAC, Linux, Mainframe), a chroot is a virtual filesystem that can be associated with a specific service, in this case SFTP.  A new protected replica of the OS folders and files relevant to running that service are created, and all files uploaded/downloaded via this service reside inside the protection of the "jail"

In Windows, the practice is typically called "Sandboxing" or Application Virtualization:

    (excerpt from Microsoft: Transform applications into managed services )

"In a physical environment, every application depends on its OS for a range of services, including memory allocation, device drivers, and much more. Incompatibilities between an application and its operating system can be addressed by either server virtualization or presentation virtualization; but for incompatibilities between two applications installed on the same instance of an OS, you need Application Virtualization.  "

And last but CERTAINLY not least:   Scan your network for rogue FTP services (Both Data Center as well as Workstation space) regularly (FREQUENTLY), find them physically, and shut them down!



References:
EITF.ORG: RFC913 - Simple File Transfer Protocol
EITF.ORG: RFC914 - A File Transfer Protocol
EITF.ORG: RFC959 - FILE TRANSFER PROTOCOL (FTP)
EITF.ORG: RFC2228 - FTP Security Extensions
IETF.ORG: secsh-filexfer (SFTP)
IETF.ORG: How to Use Anonymous FTP   -- DON'T!

IANA.ORG: Service Name and Transport Protocol Port Number Registry

TIBCO: Understanding the Impact an FTP Data Breach Can Have on Your Business
Understanding Key Differences Between FTP, FTPS and SFTP
SFTP versus FTPS – What is the best protocol for secure FTP? 
What’s the Difference? FTP, SFTP, and FTP/S 
Filezilla: SFTP specifications
http://winscp.net/eng/docs/ftps 
Using FTP? Know the Risks
wikipedia.org: Public key infrastructure 
SANS: Clear Text Password Risk Assessment Documentation
SFTP chroot 
https://wiki.archlinux.org/index.php/Change_Root
http://www.unixwiz.net/techtips/chroot-practices.html 
Oracle: Configuring and Using Chroot Jails
Winquota: Winjail 
Microsoft: Application Virtualization 

Advanced Persistent Threats, the Killchain, and FireEye...

Over the past several years, our Defence In Depth strategy has been working overtime to keep up with Advanced Persistent Threats and Zero Day Exploits. Firewalls, Intrusion Prevention, URL filtering, and AntiVirus are no longer sufficient to stave off a data breach.

Ask any Military Tactician, and they will tell you that the Defence in Depth strategy is intended to merely slow down an attacker, to buy time, and potentially exhaust the attackers resources.  In and of itself, this strategy, given time, will fall.

According to a report by analyst firm Gartner, adding more layers of defense will not necessarily improve protection from targeted threats. What is needed, the analysts say, is the evolution of better security controls.

A new way of thinking needs to be employed... A counter methodology needs to be embedded in the corporate security culture, and tooling needs to be put in place to proactively remediate against today's type of attacks.

RSA: The Malware Factory and Massive Morphing Malware

We've been hearing more and more about Advanced Persistent Threats or Advanced Volatile Threats or just Advanced Threats.. where a Threat Actor  (person/agency/government) is intent on getting access to your confidential or sensitive data, and has the time and resources to invest in a calculated exercise to achieve this goal. Malicious tools have evolved to the point where you can automate the build of thousands of variants to piece of malware, and deliver each one to a specific person or machine.  No Signature based AntiVirus on the planet would catch a one-off piece of malicious code.  

Enter FireEye® with it's  Advanced Malware Protection appliances.  Established in 2004 as a security research company, they came up with the novel concept of using Virtualization to launch and assess the activity of "payloads" such as email attachments or downloaded files.  Any attachment, executable, zip file etc.. is run within a series of sanitized virtual environments, and any unexpected activity would be flagged for analysis. One of the malicious activities identified early on was the "callback" to botnet Command and Control servers.  

As a valuable byproduct of the development of this system, FireEye amassed a large database of "known" Threat Actors.  This intelligence is then used to block any subsequent activities to those Threat Actors across FireEye's entire customer base.

When installed inline at the Internet landing zone, FireEye (Both Mail and Web) adds a proactive member to your existing reactive firewall, IPS, and URL filters.

From FireEye's report : Less Than Zero: A Survey of Zero-day Attacks in 2013 and What They Say About the Traditional Security Model

“Advanced threats against enterprises today thrive on exploiting the unknown and evading blocking techniques thanks to a growing, global marketplace for selling software vulnerabilities,” said Zheng Bu, vice president of security research, FireEye. “The old security model of tracking known threats and relying on signature-based solutions are simply powerless to stop zero-day threats. The number of zero-day attacks profiled in the paper highlight why organizations need to take a new approach to security by combining next-generation technology with human expertise.”

So we have a proactive tool to identify anomalous behaviour, and identify/prevent Zero-day attacks... Now what?

A methodology first described by Lockheed Martin, the Cyber "Kill Chain" can be used to identify, and proactively mitigate and remediate against these advanced security threats.

 

From the Lockheed Martin paper:

(I added the Red Text to show the result of implementing FireEye)

1. Reconnaissance - Research, identification and selection of targets, often represented as crawling Internet websites such as conference proceedings and mailing lists for email addresses, social relationships, or information on specific technologies. 

• If the reconnaissance is done as a form of phishing exercise, there will likely be links in the email back to a C&C server on the Internet.  Any attempt to connect to that network (ie: clicking the link) would be blocked by FireEye and generate an alert to the SIEM.

1. Weaponization - Coupling a remote access trojan with an exploit into a deliverable payload, typically by means of an automated tool (weaponizer). Increasingly, client application data files such as Adobe Portable Document Format (PDF) or Microsoft Office documents serve as the weaponized deliverable. 

• Email attachments as well as files downloaded from the Internet will be assessed by FireEye (Executed in several virtual sandboxes), and if deemed malicious, will alert the SIEM, block callbacks, and prevent further downloads.

1. Delivery - Transmission of the weapon to the targeted environment. The three most prevalent delivery vectors for weaponized payloads by APT actors, as observed by the Lockheed Martin Computer Incident Response Team (LM-CIRT) for the years 2004-2010, are email attachments, websites, and USB removable media. 

•  As in Weaponization, Email attachments as well as files downloaded from the Internet will be assessed by FireEye (Executed in several virtual sandboxes), and if deemed malicious, will alert the SIEM, block callbacks, and prevent further downloads.

1. Exploitation - After the weapon is delivered to victim host, exploitation triggers intruders’ code. Most often, exploitation targets an application or operating system vulnerability, but it could also more simply exploit the users themselves or leverage an operating system feature that auto-executes code.Installation - Installation of a remote access trojan or backdoor on the victim system allows the adversary to maintain persistence inside the environment. 

• *IF* a malicious application DOES get installed out of band, ie: from CD or USB drive, any callbacks would be blocked by FireEye, raising an alert in SIEM, and preventing subsequent communication with the C&C and subsequent downloads.

• Host Protection tools on your servers are HIGHLY recommended to prevent installation and  execution of any such malicious applications in the first place.

1. Installation - Installation of a remote access trojan or backdoor on the victim system allows the adversary to maintain persistence inside the environment.

• Host Protection tools on your servers are HIGHLY recommended to prevent installation and execution of any such malicious applications in the first place.

1. Command and Control (C2) - Typically, compromised hosts must beacon outbound to an Internet controller server to establish a C2 channel. APT malware especially requires manual interaction rather than conduct activity automatically. Once the C2 channel establishes, intruders have “hands on the keyboard” access inside the target environment.

• FireEye will block callbacks to the Command and Control, and prevent further downloads. 

1. Actions on Objectives - Only now, after progressing through the first six phases, can intruders take actions to achieve their original objectives. Typically, this objective is data exfiltration which involves collecting, encrypting and extracting information from the victim environment; violations of data integrity or availability are potential objectives as well. Alternatively, the intruders may only desire access to the initial victim box for use as a hop point to compromise additional systems and move laterally inside the network.

•  Malicious code will not be able to exfiltrate data, if callbacks are blocked, and the Command and Control IP addresses are blocked.  Again, any attempt to do so, would send alerts to the SIEM while still being blocked.

A “Kill Chain”Analysis of the 2013 Target Data Breach

I am not suggesting that FireEye in and of itself is a full Malware mitigation strategy.  I HIGHLY recommend that you also install Host Protection tools on your servers, and run  network firewall, Intrusion Prevention, layer two segregation, and Email/URL filtering as well. 

With FireEye installed in your internet egress, inspecting both Mail and Web content, you significantly reduce the risk of malware infection and subsequent Data Breach by phishing emails or drive by downloads.

References:


Dell Secureworks: Managed FireEye - Advanced Malware Protection Service
Gartner: Best-Practices-for-Mitigating-Advanced-Persistent-Threats CISCO: Advanced Malware Protection
DarkReading: FireEye Releases Comprehensive Analysis of 2013 Zero-day Attacks; Impact on Security Models 
RSA: The Malware Factory and Massive Morphing Malware 
http://www.symantec.com/theme.jsp?themeid=apt-infographic-1
Email Security (FireEye EX Series)
FireEye: Cybersecurity's Maginot Line A real World Assessment
FireEye: Advanced Threat Report 2013
FireEye: Multi-Vector Virtual Execution (MVX) engine 
http://newsroNSS Labs Ranks Cisco Advanced Malware Protection Among Top Breach Detection Systemsom.cisco.com/press-release-content?articleId=1403242
Paloalto: Advanced Persistent Threats
OWASP: Defense_in_depth
NSA: Defence in Depth
Government of Canada: Mitigation Guidelines for Advanced Persistent Threats
Lockheed Martin: Kill Chain Analysis
RSA: Adversary ROI: Evaluating Security from the Threat Actor’s Perspective
 http://www.fireeye.com/blog/technical/malware-research/2014/06/turing-test-in-reverse-new-sandbox-evasion-techniques-seek-human-interaction.html
http://www.csoonline.com/article/2134037/strategic-planning-erm/the-practicality-of-the-cyber-kill-chain-approach-to-security.html
Digital Bread Crumbs: Seven Clues To Identifying Who’s Behind Advanced Cyber Attacks
Microsoft: The evolution of malware and the threat landscape. – a 10-year review 
Kaspersky: MALWARE EVOLUTION. THE TOP SECURITY STORIES OF 2013 
McAfee Identified an Astounding 200 New Malware Samples Per Minute in 2013 
Paloalto: The Modern Malware Review