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Microsoft Patches 3 Under-Attack Windows Zero-Days

Microsoft’s Patch Tuesday bundle for July 2021 landed with a loud thud as the world’s largest software maker warns of a new wave of zero-day attacks hitting its flagship Windows operating system.

Microsoft’s Patch Tuesday bundle for July 2021 landed with a loud thud as the world’s largest software maker warns of a new wave of zero-day attacks hitting its flagship Windows operating system.

Microsoft’s embattled security response unit is urging Windows fleet administrators to prioritize fixes for three documented vulns that have already been exploited in live malware attacks.

The company did not provide details of the attacks beyond a note that three of the July bulletins cover software defects that have already been exploited by unknown adversaries.

The three exploited vulns are described as WIndows kernel privilege escalation issues (CVE-2021-31979 and CVE-2021-33771) and a scripting engine memory corruption bug (CVE-2021-34448) that expose users to drive-by attacks via web browsers.

In all, Microsoft documented 117 vulnerabilities in the Windows ecosystem, some dangerous enough to expose users to remote code execution attacks.  Microsoft rated 17 of the vulnerabilities as “critical,” the company’s highest severity rating.

The security fixes cover problems in a range of products, including Microsoft Office, Microsoft Exchange Server, Bing, SharePoint Server, Internet Explorer, Visual Studio and OpenEnclave.

[ Related: Did Microsoft Botch the PrintNightmare Patch? ]

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In addition to the already-exploited flaws, Microsoft warned that five additional issues are publicly known.  One of the publicly known issues is rated critical and introduces remote code execution risks on Microsoft Exchange Server.

The massive patch bundle comes less than a week after Microsoft released an emergency patch to address the ‘PrintNightmare’ Windows Print Spooler zero-day.   Security experts have noted problems with Redmond’s newest Print Spooler patch but Microsoft insists the fix works as intended.

Separately, Adobe issued multiple security advisories with patches for critical vulnerabilities in a wide range of software products, including the ever-present Adobe Acrobat and Reader application.

The Mountain View, Calif.-based Adobe urged Windows and macOS users to treat the PDF Reader patch with the utmost priority, because the flaws expose machines to remote code execution and privilege escalation attacks.

The Acrobat and Reader update patches at least 19 documented vulnerabilities, all carrying the “critical” or “important” security ratings. 

[ Related: Adobe: Critical Flaws in Reader, Acrobat, Illustrator ]

”Successful exploitation could lead to arbitrary code execution in the context of the current user,” Adobe warned, noting that most of the flaws are memory safety issues.

In addition to the Acrobat and Reader patches, Adobe also provided cover for another 10 documented flaws in products in Adobe Illustrator, Adobe Framemaker, Adobe Dimension and Adobe Bridge.

Adobe said it was not aware of any public exploits targeting any of the security defects. 

Related: Did Microsoft Botch the PrintNightmare Patch?

Related: Microsoft Ships Emergency Print Spooler Patch 

Related: Microsoft Releases Massive Security Patch Bundle

Related: Adobe: Critical Flaws in Reader, Acrobat, Illustrator

Written By

Ryan Naraine is Editor-at-Large at SecurityWeek and host of the popular Security Conversations podcast series. He is a security community engagement expert who has built programs at major global brands, including Intel Corp., Bishop Fox and GReAT. Ryan is a founding-director of the Security Tinkerers non-profit, an advisor to early-stage entrepreneurs, and a regular speaker at security conferences around the world.

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