Critical zero-click RCE Vulnerability Impacts Microsoft Outlook Applications

Morphisec researchers have discovered a critical zero-click remote code execution (RCE) vulnerability in Microsoft Outlook, designated CVE-2024-38021.

Unlike the previously disclosed CVE-2024-30103, this vulnerability does not require authentication, making it particularly dangerous.

EHA

This zero-click remote code execution (RCE) vulnerability poses a significant threat because it can be exploited without any user interaction, particularly when emails are received from trusted senders.

CVE-2024-38021 can have severe consequences, including data breaches, unauthorized access, and other malicious activities.

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CVE-2024-38021 Vulnerability Details

CVE-2024-38021 poses significant risks, including potential data breaches, unauthorized access, and other malicious activities. Microsoft has rated this vulnerability as “Important,” noting that it is zero-click for trusted senders but requires one-click user interaction for untrusted senders.

Morphisec has urged Microsoft to reassess the severity to “Critical” due to the broader implications and potential widespread impact.

Exploiting CVE-2024-38021 is more complex than exploiting CVE-2024-30103, which reduces the likelihood of immediate exploitation. However, if chained with another vulnerability, the attack process could be simplified, increasing the risk.

  • April 21, 2024: Morphisec reported the vulnerability to Microsoft.
  • April 26, 2024: Microsoft confirmed the vulnerability.
  • July 9, 2024: Microsoft released a patch for CVE-2024-38021 as part of its Patch Tuesday updates.

CVE-2024-38021’s zero-click nature for trusted senders and the lack of authentication requirements make it a severe threat.

Attackers could exploit this vulnerability to gain unauthorized access, execute arbitrary code, and cause substantial damage without user interaction. This opens the door to widespread exploitation, emphasizing the need for immediate mitigation measures.

Patch Release and Urgent Call to Action

To mitigate the risks associated with CVE-2024-38021, the following actions are recommended:

  • Patch Deployment: Ensure all Microsoft Outlook and Office applications are updated with the latest patches.
  • Email Security: Implement robust email security measures, including disabling automatic email previews if possible.
  • User Awareness: Educate users about the risks of opening emails from unknown or suspicious sources.

Microsoft’s quick response to this vulnerability is commendable, especially given its problematic nature and the complexity of the previous patch. However, reassessing the severity to “Critical” is crucial to reflect the true risk and ensure adequate attention and resources for mitigation.

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Gurubaran is a co-founder of Cyber Security News and GBHackers On Security. He has 10+ years of experience as a Security Consultant, Editor, and Analyst in cybersecurity, technology, and communications.