New Windows 0Day Attack Confirmed—Homeland Security Says Update Now

Microsoft has confirmed a zero-day security vulnerability that can open up Windows devices to full system compromise is under active exploitation. The cyberattack has also been confirmed by the U.S. Cybersecurity and Infrastructure Security Agency, part of the Department of Homeland Security, which has added the security issue to the Known Exploited Vulnerability Catalog, and advised it “poses significant risks” with a recommendation for all users to take appropriate remediation measures and update now. Here’s what you need to know about CVE-2024-49138.

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The CVE-2024-49138 Threat To Windows Users

The December round of Patch Tuesday vulnerability fixes has been released by Microsoft, and among the 72 vulnerabilities this month is one that needs your full attention right now: CVE-2024-49138.

Not much is known about the vulnerability itself, as is often the case with such zero-day issues this detail is held back until as many users as possible have had the opportunity to patch against the exploit. However, what we do know is that it’s a heap-based buffer overflow vulnerability, a memory security issue, in the Microsoft Windows Common Log File System driver. We also know that it is a very widespread vulnerability impacting millions of Windows users.

“The vulnerability affects all Windows OS editions back to Server 2008,” Chris Goettl, vice president of security product management at Ivanti, said. “The CVE is rated Important by Microsoft and has a CVSSv3.1 score of 7.8. Risk-based prioritization would rate this vulnerability as Critical which makes the Windows OS update this month your top priority.”

CISA also sees this as being a top priority, having added it to the KEV catalog along with stating that it “CISA strongly urges all organizations to reduce their exposure to cyberattacks by prioritizing timely remediation” of the critical issue.

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The Ransomware Risk Posed By CVE-2024-49138 To Windows Users

Given that Microsoft has said that it has evidenc

e of in-the-wild exploitation and public disclosure for CVE-2024-49138, it’s no wonder that this is being seen as a critical security moment for Windows users. Although, as Adam Barnett, lead software engineer at Rapid7, sagely pointed out, “for the third month in a row, Microsoft has published zero-day vulnerabilities on Patch Tuesday without evaluating any of them as critical severity at time of publication.” Why is this important? Because Windows Common Log File System exploits are a favorite among cybercriminals, especially those participating in the ransomware sector. “Ransomware authors who have abused previous CLFS vulnerabilities will be only too pleased to get their hands on a fresh one,” Barnett said, “expect more CLFS zero-day vulnerabilities to emerge in the future, at least until Microsoft performs a full replacement of the aging CLFS codebase instead of offering spot fixes for specific flaws.” I have approached Microsoft for a statement.

In the meantime, all Windows users are urged to update now.

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