Security vulnerability in Follina exploit

Preventing exploitation of the Follina vulnerability in MSDT

Adam King

8th June 2022

4 min read

This article provides a synopsis of the Follina exploit and simple steps you can take to mitigate this severe remote code execution vulnerability within Microsoft Support Diagnostic Tool (MSDT). This vulnerability is triggered via common Windows applications such as Microsoft Word and is being actively exploited by known hacking groups.

The Follina Exploit

A zero-click Remote Code Execution (RCE) vulnerability has started making the rounds which is leveraging functionality within applications such as Microsoft Word. This vulnerability exists when the application calls MSDT using the URL protocol and allows remote attackers to execute PowerShell code on the victim’s device, under the context of the application user. In addition to this, the exploit can be triggered whilst previewing the document only. The exploit has been dubbed “Follina” and is registered as CVE-2022-30190.

Due to the nature of the exploit and how it is triggered, it is expected that an increased amount of exploitation attempts in the wild will be made via threat actors sending malicious files via phishing. You can read more about phishing attacks and how to protect against them in this blog post.

Severity and Proof of Concept

The exploit has been given a CVSSv3 rating of 7.8. The vulnerability was originally reported by crazyman of the Shadow Chaser Group and impacts all Windows versions still receiving security updates (Windows 7+ and Windows Server 2008+). Proof-of-Concept (PoC) exploit code has been released publicly, with a module being released in the popular exploit framework Metasploit.

Official Patch Status

Microsoft have yet to release an update at the time of writing (08/06/2022) to patch this vulnerability, however they have released guidance for mitigating the issue on their Microsoft Security Response Center (MSRC) blog to reduce the attack surface. It is highly recommended that this workaround is applied until an official patch is released by Microsoft.

Mitigation and Workaround Steps

As described by Microsoft, the following actions must be taken to perform the workaround.

Run Command Prompt as Administrator.
To back up the registry key, execute the command “reg export HKEY_CLASSES_ROOT\ms-msdt filename“
Execute the command “reg delete HKEY_CLASSES_ROOT\ms-msdt /f”.


To undo, simply import the backup of the registry key.

Run Command Prompt as Administrator.
To restore the registry key, execute the command “reg import filename”


The MSRC also details how Microsoft Defender solutions can detect and alert on potential exploit activity.

Whilst the remediation steps appear to have no adverse impact on a system during our testing, it should be noted that any modification of the registry can cause unwanted behaviours in Windows operating systems and should be tested thoroughly.

We have created a PowerShell script that will backup the targeted registry key before removing it, automating the workaround steps highlighted above. You can find this script on our public GitHub.  This script may be deployed through Microsoft InTune and other MDM solutions to patch multiple vulnerable systems.



  • Insights
  • Labs
API penetration testing

Securing APIs through penetration testing

APIs (Application Programming Interfaces) have become the backbone of many modern applications, and indeed the foundation of some businesses services. APIs enable seamless communication between…

The importance of a post-penetration test action plan

The importance of a post-penetration test action plan

As cyber threats continue to evolve and become more sophisticated, businesses must stay one step ahead in protecting their sensitive data and network infrastructure. Penetration…

How to choose the right penetration testing partner

How to choose the right penetration testing partner for your business

In today’s digital landscape, cybersecurity threats are evolving at an alarming rate. With the growing number of cyber-attacks and data breaches, businesses must prioritise their…

IoT device security, penetration testing

Securing the Internet of Things: Penetration testing’s role in IoT device security

The world is witnessing a remarkable transformation as more devices become interconnected, forming what’s known as the Internet of Things (IoT). From smart refrigerators and…

Man working as a junior penetration tester

My first month working as a junior penetration tester

Entering the world of cyber security as a junior penetration tester has been an eye-opening experience for me. In my first month, I’ve encountered challenges,…

The role of penetration testing in cybersecurity

The role of penetration testing in cybersecurity

Cybersecurity forms the backbone of safeguarding your business’s data. With cybercrime becoming more sophisticated, traditional security measures are often insufficient. Staying vigilant and proactive is…

Password cracking: How to crack a password

An introduction to password security: How to crack a password

Online Password Cracking An online attack is performed in real-time, against live services or applications to compromise active user accounts. Such attacks typically occur when…

Application Security 101 – HTTP headers

Application Security 101 – HTTP Headers Information Disclosure

Server Header Information Disclosure The most common HTTP header that is enabled by default in most web servers is the ‘Server’ header, which can lead…

SPF, DKIM, DMARC and BIMI for Email Security

SPF, DKIM, DMARC and BIMI for Email Security

Sender Policy Framework Sender Policy Framework (SPF) is a DNS TXT record that is added to a domain that tells email recipients which IP addresses…

Terraform security best practices

Terraform security best practices (2022)

The following sections discuss our most important Terraform security best practices: The importance of Terraform State Terraform must keep track of the resources created. When…

Application Security 101 – HTTP headers

Application Security 101 – HTTP headers

1. Strict-Transport-Security The HTTP Strict Transport Security (HSTS) header forces browsers and other agents to interact with web servers over the encrypted HTTPS protocol, which…