VDI Security Best Practices: Busting the Myths

As 2022 begins and remote work has gone from a growing trend to a necessity for many enterprise companies around the globe, administrators and management are re-evaluating their enterprise VDI solutions.

“From a cyber and data security perspective, as well as a technological perspective, there are many challenges with the current environment,” says Steven Estep, director of operational risk for Independent Community Bankers of America. Part of the issue, he says, is how quickly financial institutions had to set up work-from-home capabilities and how reliant they are on new business tools needed for secure remote collaboration.

CISOs and security professionals often refer to Virtual Desktop Infrastructure (VDI) (made popular by VMWare & Citrix) and other “remote application” solutions as security barriers that hackers have a hard time bypassing.  This is a myth, here’s why:

1. Thin client scenarios are precarious

These virtualization efforts pose only a minor hurdle to determined cyber-criminals. An employee using a thin client to connect to a remote VDI environment running Windows is not better off security-wise than any other Windows laptop user. The remote Windows desktop is still exposed to a variety of standard malware and attack vectors, including email, web, external media, user-installed applications, and many others.

These attacks have increased in 2021 as hackers take advantage of so many workers being moved quickly to a work from home model.  “According to the Identity Theft Resource Center (ITRC) The number of data breaches publicly reported so far this year has already exceeded the total for 2020, putting 2021 on track for a record year. Eva Velasquez, President and CEO of the ITRC, said 2021 is just 238 breaches away from tying the record for a single year. “It’s also interesting to note that the 1,111 data breaches that the amount and quality of data being exfiltrated by hackers. from cyber-attacks so far, this year exceeds the total number of data compromises from all causes in 2020.”

2. BYOD sounds appealing, but these laptops are probably already compromised

In many cases, employees are allowed to connect to their corporate VDI desktops from unmanaged devices such as personal laptops (known as Bring Your Own Device policies) – which are probably compromised already. In such a scenario, the attacker first gains control over the end user’s personal laptop; he then impersonates the user and interacts with the remote VDI desktop. This doesn’t require attacker sophistication – it’s as simple as installing commoditized off-the-shelf remote control software on the user’s personal laptop, waiting for the user to authenticate, and then controlling the VDI session in the user’s name.

Preventing clipboard operations between the user’s personal laptop and the remote VDI desktop doesn’t really help. Attackers can stealthily and instantly send an entire script via emulated keystrokes and then launch the script on the remote VDI desktop. From there, the way to complete control of the VDI desktop is short. This kind of attack doesn’t require any zero-day vulnerability and can be executed by any determined attacker.

3. You need to consider your vendors’ endpoints

The same applies to third-party vendors and contractors who use VDI to access sensitive resources. As seen in the Target, Equifax, and Panama and Paradise papers breaches, cyber-criminals only need to infect one of the vendor’s machines and from there they have complete control of the sensitive resources available via VDI. Two-factor authentication for VDI sessions doesn’t help mitigate this risk as the attacker, already present on the machine, will simply wait for successful authentication and then launch the attack.

4. VDI and Jumphosts

The false sense of security provided by VDI can be very misleading and, in some cases, can have catastrophic consequences. Some enterprises let their IT administrators connect to privileged management consoles via jump hosts or jump boxes hosted on VDI terminal servers. While jump hosts are a healthy practice, the problem starts when the device used to access these privileged jump hosts is a compromised personal device, which is often the case. The bad guys look for IT administrators and target them personally; once they infect an IT administrator’s personal device, they can literally control the entire organization over VDI.

5. VDI Doesn’t Prevent Data Leaks

Despite common perception, it is quite easy for attackers to exfiltrate data from VDI desktops. Here is why:

  • It doesn’t matter how many authentication factors you use to authenticate to VDI. The attacker would just wait for the user to complete the authentication and then ride their session to do harm.
  • It doesn’t matter if you check the physical laptop by running all kinds of OS health checks as part of a “conditional access” model. Just like a drunk man can’t tell if he’s drunk, the OS can’t tell if it’s infected with malware if it’s infected with malware. OS health checks are good basic hygiene but cannot really detect many types of malware that can infect personal laptops.
  • The VDI desktop is typically an internet-connected Windows OS – it has access to email, some internet browsing, cloud applications, etc. This means that the VDI desktop can and will become infected, unless the OS is completely locked down. If the VDI desktop is infected, malware can extract any data out of it or do harm. If you’re hosting VDI desktops in your data center, malware on the
  • VDI desktop can now spread in your data center by moving laterally.
  • Specifically for published apps (as opposed to full VDI desktops) – if one of these apps has a software vulnerability, leveraging that vulnerability can lead to malware running in a single server OS that co-hosts multiple user sessions/apps. Malware now has access to all of those user sessions and to a whole lot of sensitive data in just one shot.

6. True OS Isolation is Key

VDI is not an isolation solution. It does not isolate the remote sensitive resources from the device used by the user to access them. If you control the user’s device, you control the VDI resources.

It’s paramount that enterprises realize this risk and completely isolate access to sensitive resources. Local or remote access of sensitive resources should not be mixed with other usage, such as personal or corporate use that is exposed to the outside world. This practice is recommended by security vendors and financial industry institutions, including vendors like Microsoft and SWIFT that recommend using a separate instance of an operating system for accessing sensitive resources.

Hysolate: An Isolated, Fully Managed OS on User Endpoints

Hysolate offers an alternative that solves the security challenges of VDI, in the form of a fully managed, fully isolated OS that sits on user endpoints, and is fully managed from the cloud.

With Hysolate your distributed workers (employees and contractors) have two fully isolated workspaces, with full isolation between them. Corporate data is totally separated from everyday riskier activities and websites. Administrators can easily deploy, administer and shut down workspaces from the cloud, saving data center costs and IT headaches.

Users have a better user experience, with full access to necessary web and desktop applications they need to do their jobs. Isolated desktops also eliminate lags, performance issues, and other user experience issues that are common to VDIs.

To find out more you can sign up for a demo, or try Hysolate Free here.

Written in December 2019, updated for accuracy in November 2021.

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*** This is a Security Bloggers Network syndicated blog from Hysolate authored by Tal Zamir. Read the original post at: