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Microsoft Corp. today issued software updates to plug at least 139 security holes in various flavors of Windows and other Microsoft products. Redmond says attackers are already exploiting at least two of the vulnerabilities in active attacks against Windows users.
The first Microsoft zero-day this month is CVE-2024-38080, a bug in the Windows Hyper-V component that affects Windows 11 and Windows Server 2022 systems. CVE-2024-38080 allows an attacker to increase their account privileges on a Windows machine. Although Microsoft says this flaw is being exploited, it has offered scant details about its exploitation.
The other zero-day is CVE-2024-38112, which is a weakness in MSHTML, the proprietary engine of Microsoft’s Internet Explorer web browser. Kevin Breen, senior director of threat research at Immersive Labs, said exploitation of CVE-2024-38112 likely requires the use of an “attack chain” of exploits or programmatic changes on the target host, a la Microsoft’s description: “Successful exploitation of this vulnerability requires an attacker to take additional actions prior to exploitation to prepare the target environment.”
“Despite the lack of details given in the initial advisory, this vulnerability affects all hosts from Windows Server 2008 R2 onwards, including clients,” Breen said. “Due to active exploitation in the wild this one should be prioritized for patching.”
Satnam Narang, senior staff research engineer at Tenable, called special attention to CVE-2024-38021, a remote code execution flaw in Microsoft Office. Attacks on this weakness would lead to the disclosure of NTLM hashes, which could be leveraged as part of an NTLM relay or “pass the hash” attack, which lets an attacker masquerade as a legitimate user without ever having to log in.
“One of the more successful attack campaigns from 2023 used CVE-2023-23397, an elevation of privilege bug in Microsoft Outlook that could also leak NTLM hashes,” Narang said. “However, CVE-2024-38021 is limited by the fact that the Preview Pane is not an attack vector, which means that exploitation would not occur just by simply previewing the file.”
The security firm Morphisec, credited with reporting CVE-2024-38021 to Microsoft, said it respectfully disagrees with Microsoft’s “important” severity rating, arguing the Office flaw deserves a more dire “critical” rating given how easy it is for attackers to exploit.
“Their assessment differentiates between trusted and untrusted senders, noting that while the vulnerability is zero-click for trusted senders, it requires one click user interaction for untrusted senders,” Morphisec’s Michael Gorelik said in a blog post about their discovery. “This reassessment is crucial to reflect the true risk and ensure adequate attention and resources are allocated for mitigation.”
In last month’s Patch Tuesday, Microsoft fixed a flaw in its Windows WiFi driver that attackers could use to install malicious software just by sending a vulnerable Windows host a specially crafted data packet over a local network. Jason Kikta at Automox said this month’s CVE-2024-38053 — a security weakness in Windows Layer Two Bridge Network — is another local network “ping-of-death” vulnerability that should be a priority for road warriors to patch.
“This requires close access to a target,” Kikta said. “While that precludes a ransomware actor in Russia, it is something that is outside of most current threat models. This type of exploit works in places like shared office environments, hotels, convention centers, and anywhere else where unknown computers might be using the same physical link as you.”
Automox also highlighted three vulnerabilities in Windows Remote Desktop a service that allocates Client Access Licenses (CALs) when a client connects to a remote desktop host (CVE-2024-38077, CVE-2024-38074, and CVE-2024-38076). All three bugs have been assigned a CVSS score of 9.8 (out of 10) and indicate that a malicious packet could trigger the vulnerability.
Tyler Reguly at Fortra noted that today marks the End of Support date for SQL Server 2014, a platform that according to Shodan still has ~110,000 instances publicly available. On top of that, more than a quarter of all vulnerabilities Microsoft fixed this month are in SQL server.
“A lot of companies don’t update quickly, but this may leave them scrambling to update those environments to supported versions of MS-SQL,” Reguly said.
It’s a good idea for Windows end-users to stay current with security updates from Microsoft, which can quickly pile up otherwise. That doesn’t mean you have to install them on Patch Tuesday. Indeed, waiting a day or three before updating is a sane response, given that sometimes updates go awry and usually within a few days Microsoft has fixed any issues with its patches. It’s also smart to back up your data and/or image your Windows drive before applying new updates.
For a more detailed breakdown of the individual flaws addressed by Microsoft today, check out the SANS Internet Storm Center’s list. For those admins responsible for maintaining larger Windows environments, it often pays to keep an eye on Askwoody.com, which frequently points out when specific Microsoft updates are creating problems for a number of users.
As ever, if you experience any problems applying any of these updates, consider dropping a note about it in the comments; chances are decent someone else reading here has experienced the same issue, and maybe even has a solution.
If only Patch Tuesdays came around infrequently — like total solar eclipse rare — instead of just creeping up on us each month like The Man in the Moon. Although to be fair, it would be tough for Microsoft to eclipse the number of vulnerabilities fixed in this month’s patch batch — a record 147 flaws in Windows and related software.
Yes, you read that right. Microsoft today released updates to address 147 security holes in Windows, Office, Azure, .NET Framework, Visual Studio, SQL Server, DNS Server, Windows Defender, Bitlocker, and Windows Secure Boot.
“This is the largest release from Microsoft this year and the largest since at least 2017,” said Dustin Childs, from Trend Micro’s Zero Day Initiative (ZDI). “As far as I can tell, it’s the largest Patch Tuesday release from Microsoft of all time.”
Tempering the sheer volume of this month’s patches is the middling severity of many of the bugs. Only three of April’s vulnerabilities earned Microsoft’s most-dire “critical” rating, meaning they can be abused by malware or malcontents to take remote control over unpatched systems with no help from users.
Most of the flaws that Microsoft deems “more likely to be exploited” this month are marked as “important,” which usually involve bugs that require a bit more user interaction (social engineering) but which nevertheless can result in system security bypass, compromise, and the theft of critical assets.
Ben McCarthy, lead cyber security engineer at Immersive Labs called attention to CVE-2024-20670, an Outlook for Windows spoofing vulnerability described as being easy to exploit. It involves convincing a user to click on a malicious link in an email, which can then steal the user’s password hash and authenticate as the user in another Microsoft service.
Another interesting bug McCarthy pointed to is CVE-2024-29063, which involves hard-coded credentials in Azure’s search backend infrastructure that could be gleaned by taking advantage of Azure AI search.
“This along with many other AI attacks in recent news shows a potential new attack surface that we are just learning how to mitigate against,” McCarthy said. “Microsoft has updated their backend and notified any customers who have been affected by the credential leakage.”
CVE-2024-29988 is a weakness that allows attackers to bypass Windows SmartScreen, a technology Microsoft designed to provide additional protections for end users against phishing and malware attacks. Childs said one of ZDI’s researchers found this vulnerability being exploited in the wild, although Microsoft doesn’t currently list CVE-2024-29988 as being exploited.
“I would treat this as in the wild until Microsoft clarifies,” Childs said. “The bug itself acts much like CVE-2024-21412 – a [zero-day threat from February] that bypassed the Mark of the Web feature and allows malware to execute on a target system. Threat actors are sending exploits in a zipped file to evade EDR/NDR detection and then using this bug (and others) to bypass Mark of the Web.”
Update, 7:46 p.m. ET: A previous version of this story said there were no zero-day vulnerabilities fixed this month. BleepingComputer reports that Microsoft has since confirmed that there are actually two zero-days. One is the flaw Childs just mentioned (CVE-2024-21412), and the other is CVE-2024-26234, described as a “proxy driver spoofing” weakness.
Satnam Narang at Tenable notes that this month’s release includes fixes for two dozen flaws in Windows Secure Boot, the majority of which are considered “Exploitation Less Likely” according to Microsoft.
“However, the last time Microsoft patched a flaw in Windows Secure Boot in May 2023 had a notable impact as it was exploited in the wild and linked to the BlackLotus UEFI bootkit, which was sold on dark web forums for $5,000,” Narang said. “BlackLotus can bypass functionality called secure boot, which is designed to block malware from being able to load when booting up. While none of these Secure Boot vulnerabilities addressed this month were exploited in the wild, they serve as a reminder that flaws in Secure Boot persist, and we could see more malicious activity related to Secure Boot in the future.”
For links to individual security advisories indexed by severity, check out ZDI’s blog and the Patch Tuesday post from the SANS Internet Storm Center. Please consider backing up your data or your drive before updating, and drop a note in the comments here if you experience any issues applying these fixes.
Adobe today released nine patches tackling at least two dozen vulnerabilities in a range of software products, including Adobe After Effects, Photoshop, Commerce, InDesign, Experience Manager, Media Encoder, Bridge, Illustrator, and Adobe Animate.
KrebsOnSecurity needs to correct the record on a point mentioned at the end of March’s “Fat Patch Tuesday” post, which looked at new AI capabilities built into Adobe Acrobat that are turned on by default. Adobe has since clarified that its apps won’t use AI to auto-scan your documents, as the original language in its FAQ suggested.
“In practice, no document scanning or analysis occurs unless a user actively engages with the AI features by agreeing to the terms, opening a document, and selecting the AI Assistant or generative summary buttons for that specific document,” Adobe said earlier this month.
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