Microsoft Patches 9 Zero-Days with July 2021 Update

Overview

Microsoft patches a total of 97 operating system and software flaws with July 2021 Patch Tuesday update. 9 of these vulnerabilities turn out to be zero-day vulnerabilities, and 4 of them are considered to be actively exploited in the wild.

What Is Patch Tuesday?

Patch Tuesday, a.k.a., Black Tuesday (or Update Tuesday), is an unofficial term used to refer to the scheduled updates rolled out on Tuesdays by Microsoft to fix for known bugs in the Windows operating system and the other Microsoft products.

It was introduced in 2003 to provide a routine schedule for the system administrators to plan for updates for Microsoft products. The idea was to simplify the patch management by regular schedules and save the network administrators from the hassle of unpredictable updates. With predetermined update schedules, system administrators could arrange compatibility and deployment tests before installing the updates.

About the Security Vulnerabilities

Microsoft patches several of its products with the Patch Tuesday update in July. 9 of the vulnerabilities, from a total of 97, turn out to be zero-days, and 4 of these zero-day vulnerabilities are actively exploited in the wild, according to the Microsoft update guide.

Out of these 97 vulnerabilities, 2 are rated critical and 70 are rated high in severity according to CVSS (Common Vulnerability Scoring System) scale. However, note that these initial ratings made currently by Microsoft could differ from the final severity evaluation in NVD (National Vulnerability Database).

Zero-Day Vulnerabilities

Following is a list of zero-day vulnerabilities that were detected to be actively exploited in the wild. Among these, CVE-2021-34527 Print Spooler vulnerability, a.k.a., PrintNightmare vulnerability, was patched last week with an emergency update, as it was accidentally disclosed publicly by Chinese researchers.

1. CVE-2021-34527 Windows Print Spooler Remote Code Execution Vulnerability
2. CVE-2021-31979 Windows Kernel Elevation of Privilege Vulnerability
3. CVE-2021-34448 Scripting Engine Memory Corruption Vulnerability
4. CVE-2021-33771 Windows Kernel Elevation of Privilege Vulnerability

According to a report by Citizen Lab, two of these vulnerabilities (CVE-2021-31979 and CVE-2021-33771) were found to be exploited by a spyware that was allegedly developed by an Israeli cyber security company called Candiru. Microsoft Threat Intelligence Center (MSTIC) further shared that at least 100 human rights defenders, dissidents, journalists, activists and politicians in Palestine, Israel, Iran, Lebanon, Yemen, Spain, United Kingdom, Turkey, Armenia, and Singapore fell victims of this spyware.

The other 5 zero-day vulnerabilities that have no known exploits at the time of the patch release are as follows:

1. CVE-2021-33781 Azure AD Security Feature Bypass Vulnerability
2. CVE-2021-33779 Windows ADFS Security Feature Bypass Vulnerability
3. CVE-2021-34473 Microsoft Exchange Server Remote Code Execution Vulnerability
4. CVE-2021-34523 Microsoft Exchange Server Elevation of Privilege Vulnerability
5. CVE-2021-34492 Windows Certificate Spoofing Vulnerability

Vulnerabilities That Are Not Zero-Days

The following is a list of the remaining 88 vulnerabilities that are not zero-days:

References to Advisories, Solutions and Tools

• Microsoft Security Update Guide

One single vulnerability all an attacker needs.

Window Snyder

Read more educational and inspirational cyber quotes at our page 100+ Best Cyber Security & Hacker Quotes.

To learn more about security vulnerabilities, you could also read our articles What is a Security Vulnerability? or What is Vulnerability Scanning?