Hackers exploit Microsoft Teams for ransomware

Russian hackers are exploiting Microsoft Teams to launch sophisticated ransomware attacks. Learn about their methods in this article.

23-01-2025 - 8 minute read. Posted in: cybercrime.

Hackers exploit Microsoft Teams for ransomware

How hackers turn Microsoft Teams into a ransomware nightmare

Sophos, a leading name in cybersecurity, has uncovered two alarming ransomware campaigns targeting companies that use Microsoft Teams. The hackers utilize email bombing as a method to bypass security measures and deceive employees. Let’s dive into what’s happening and how you can protect your organization.

Meet the ransomware attackers: Storm-1811 and FIN7

Two Russian hacking groups, Storm-1811 and FIN7, are at the heart of these attacks. Storm-1811 is known for its aggressive tactics and focus on large-scale disruption, while FIN7 has a history of precision strikes aimed at extracting financial gain. These groups are part of larger ransomware groups known for their sophisticated and persistent attacks. By working separately but employing similarly advanced techniques, these groups highlight just how sophisticated and persistent modern cybercriminals can be.

These groups are not amateurs. They’ve been linked to high-profile incidents globally, and their methods constantly evolve to stay ahead of detection systems. Their recent campaigns show a shift toward exploiting trusted platforms like Microsoft Teams, which organizations rely on for internal communication.

Inside the ransomware attack: Breaking down their strategy

The attacks follow a deliberate and multi-step strategy, blending technology with psychological manipulation to achieve their goals. Here’s how they operate, step by step:

  1. Choosing targets: Attackers start by identifying a specific group of employees at a company, usually one that relies heavily on Microsoft Teams for communication. This increases the chance of their tactics succeeding.

  2. Email bombing: Once the targets are identified, attackers send thousands of spam emails to overwhelm their inboxes. This flood of emails isn’t just annoying; it’s a deliberate move to hide critical alerts and make it harder for employees to spot phishing attempts. Sophos x-Ops reported that in one instance, over 3,000 emails were sent to a single user in under an hour. If you’d like to learn more about how phishing works and how to avoid it, check out our guide on what is phishing.

  3. Infiltrating Microsoft Teams: With login credentials obtained via phishing or brute-force attacks, hackers infiltrate Microsoft Teams. Here, they impersonate IT support staff, sending convincing messages that ask employees to click on links or share sensitive information. These messages often look legitimate, making them harder to spot as fraudulent. Want to discover how brute-force attacks operate and why they’re so effective? Read our detailed article on what is a brute force attack.

  4. Voice phishing (vishing): To add credibility, the attackers follow up with phone calls. Pretending to be IT personnel, they tell employees they are resolving the email issue and guide them into granting access through Teams’ screen sharing or remote control features.

  5. Taking control: Using remote screen-sharing tools like Quick Assist or Microsoft Teams’ own features, hackers take control of the target’s computer. This access is then used to deploy ransomware, encrypting files and systems.

  6. Ransomware deployment: With access to critical systems, attackers deploy ransomware that locks down an organization’s data. The ransomware is designed to encrypt files on the victim's system, making them inaccessible until a ransom is paid. Victims are then presented with demands for ransom payments in exchange for decrypting their files, often under the threat of permanent data loss or public exposure.

The role of Microsoft Teams in ransomware attacks

Microsoft Teams has become an essential tool for communication and collaboration in many organizations. However, its widespread use has also made it a target for ransomware attackers. These cybercriminals exploit the platform to spread malware and gain unauthorized access to victims’ systems. The trusted nature of Microsoft Teams can make employees less vigilant, providing an opportunity for attackers to infiltrate systems and deploy ransomware.

How Microsoft Teams is used in ransomware attacks

Ransomware attackers have found various ways to exploit Microsoft Teams to spread malware. One common method is through phishing emails containing malicious links. When a victim clicks on the link, malware is downloaded, and the ransomware is installed on their system. The attacker can then encrypt the victim’s files and demand a ransom.

In some instances, attackers use Microsoft Teams to deliver ransomware programs directly to victims’ systems. This is often achieved through a malicious link or attachment sent via a Teams message. Once the victim interacts with the link or attachment, the ransomware is deployed, leading to file encryption and a ransom demand.

To protect against these attacks, organizations must implement robust security measures, including regular backups, anti-virus software, and comprehensive employee education on cybersecurity best practices. Additionally, it is crucial to exercise caution when using Microsoft Teams and other communication platforms, avoiding suspicious links and attachments from unknown sources.

Why your organization should be concerned

The use of Microsoft Teams as an attack vector is a concerning development. As a widely trusted communication tool, Teams is often seen as a safe space for collaboration. This perception can make employees less cautious, giving attackers an edge. Recent ransomware attacks have increasingly targeted trusted communication platforms, making it a pressing concern for organizations. Combined with email bombing and vishing, these tactics create a perfect storm that can catch even the most security-conscious organizations off guard.

For more tips on how to secure your workplace against attacks like these, read our guide on network security: a top 10 of best practices.

Steps to stay protected from encrypting ransomware

At Moxso, we believe in proactive defense. Here’s how your organization can protect itself from these sophisticated attacks:

  • Train your team: Cybersecurity awareness is your first line of defense. Regular training helps employees recognize phishing emails, suspicious calls, and fake IT messages, even when they’re disguised within trusted platforms like Microsoft Teams. Additionally, educate employees about the risks of mobile ransomware and how it can infiltrate their devices through seemingly legitimate apps. To learn why training is essential, explore our article on why gamification in awareness training works.

  • Enable multi-factor authentication (MFA): MFA provides an extra layer of security, making it significantly harder for attackers to access accounts, even if they’ve stolen passwords.

  • Use advanced email filters: Robust filtering systems can detect and block spam or phishing emails before they reach employees, reducing the effectiveness of email bombing.

  • Monitor for unusual activity: Deploy real-time monitoring tools to detect and respond to suspicious behavior, such as unexpected logins or unauthorized access to communication platforms. It's also crucial to monitor for unauthorized access through remote desktop protocol to prevent ransomware attacks.

  • Encourage reporting: Create a workplace culture where employees feel safe reporting anything unusual. Quick reporting can prevent a minor incident from escalating into a full-blown attack.

The Rise of ransomware attacks

Ransomware attacks have surged in recent years, affecting organizations of all sizes and across various industries. These attacks can lead to severe financial losses, data theft, and significant damage to a company’s reputation. The increasing frequency and sophistication of these attacks highlight the urgent need for robust cybersecurity measures. Understanding the nature of ransomware and its potential impact is crucial for any organization looking to protect itself from these pervasive threats. To learn more about how ransomware has evolved and how to stay protected, read our article on what is ransomware as a service.

What is a ransomware attack?

A ransomware attack is a type of cyber attack where attackers gain unauthorized access to a victim’s computer system or network and encrypt their files. The attackers then demand a ransom in exchange for the decryption key needed to restore access to the encrypted files. Ransomware attackers often use digital currencies like Bitcoin for ransom payments, making it difficult to trace and prosecute them. These attacks can cripple an organization’s operations, leading to significant downtime and financial loss.

How ransomware works

Ransomware typically exploits vulnerabilities in operating systems or employs social engineering tactics to trick victims into downloading malicious software. Once installed, the ransomware encrypts the victim’s files, rendering them inaccessible. The attacker then demands a ransom for the decryption key, which is required to unlock the encrypted files. This process can be devastating for organizations, as it not only disrupts operations but also puts sensitive data at risk. Understanding how ransomware works is the first step in developing effective defenses against these attacks.

Staying one step ahead

The ingenuity of these ransomware campaigns underscores the evolving nature of cyber threats. Different ransomware variants exploit vulnerabilities in various ways, making it crucial to stay informed. However, with the right tools, knowledge, and vigilance, organizations can significantly reduce their risk of falling victim.

At Moxso, we’re committed to helping businesses stay ahead of these challenges. The increasing threat of widespread ransomware attacks, facilitated by phishing campaigns and the availability of malware kits, highlights the need for robust defenses. Our tailored solutions and training programs empower teams to detect and respond to threats effectively, building a robust defense against even the most persistent attackers.

Author Sarah Krarup

Sarah Krarup

Sarah studies innovation and entrepreneurship with a deep interest in IT and how cybersecurity impacts businesses and individuals. She has extensive experience in copywriting and is dedicated to making cybersecurity information accessible and engaging for everyone.

View all posts by Sarah Krarup

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