Patch Tuesday: Microsoft Fixes 2 Office Zero-Days, Critical Team Flaw

Microsoft fixed 74 security issues in its August Patch Tuesday release, including two that were being actively exploited and twenty-three that allowed remote code execution.

Although twenty-three RCE flaws were addressed, Microsoft only categorized six of them as ‘Critical,’ and 67 have a severity rating of ‘Important.’

Flaws In Each Type Of Vulnerability

• 18 Elevation of Privilege vulnerabilities
• 3 Security Feature Bypass vulnerabilities
• 23 Remote Code Execution vulnerabilities
• 10 Information Disclosure vulnerabilities
• 8 Denial of Service vulnerabilities
• 12 Spoofing vulnerabilities

Twelve vulnerabilities in Microsoft Edge (Chromium) that were addressed earlier this month are not included in the data.

Two Vulnerabilities Actively Exploited In The Wild

A vulnerability is considered a zero-day by Microsoft if it has been made public or is being actively used without an official fix.

Patch Tuesday this month addresses two zero-day vulnerabilities:

ADV230003 – Microsoft Office Defense in Depth Update (publicly disclosed):

To address a patch bypass of the previously mitigated and actively used CVE-2023-36884 remote code execution vulnerability, Microsoft has published an Office Defence in Depth update.

The Mark of the Web (MoTW) security feature might be bypassed by threat actors by employing specially crafted Microsoft Office documents.

This would allow files to be opened without showing a security warning and would allow remote code execution.

“An attacker could create a specially crafted Microsoft Office document that enables them to perform remote code execution in the context of the victim. However, an attacker would have to convince the victim to open the malicious file.” reads the advisory published by Microsoft.

The RomCom hacker group, which had been known to use the Industrial Spy ransomware in attacks, actively exploited the vulnerability.

Since then, the ransomware operation has changed its name to “Underground,” under which it still extorts people. Paul Rascagneres and Tom Lancaster used Volexity to find the cause of the issue.

CVE-2023-38180 – .NET and Visual Studio Denial of Service Vulnerability

An actively exploited vulnerability that might lead to a DoS attack on Visual Studio and .NET applications has been addressed by Microsoft.

Unfortunately, Microsoft did not identify who found the vulnerability or provide any other information on how this bug was applied in attacks.

Additionally, three problems with Microsoft Message Queuing Remote Code Execution listed as CVE-2023-35385/36910/36911 (CVSS of 9.8) are among the most severe vulnerabilities that Microsoft has patched.

On a vulnerable server at the level of the Message Queuing service, a remote anonymous attacker can cause the vulnerability to execute malicious code.

The full list of vulnerabilities released by Microsoft for August 2023 is available here.

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