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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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Microsoft today released software updates to fix at least four dozen security holes in its Windows operating systems and other software, including patches for two zero-day vulnerabilities that are already being exploited in active attacks.
First up in May’s zero-day flaws is CVE-2023-29336, which is an “elevation of privilege” weakness in Windows which has a low attack complexity, requires low privileges, and no user interaction. However, as the SANS Internet Storm Center points out, the attack vector for this bug is local.
“Local Privilege escalation vulnerabilities are a key part of attackers’ objectives,” said Kevin Breen, director of cyber threat research at Immersive Labs. “Once they gain initial access they will seek administrative or SYSTEM-level permissions. This can allow the attacker to disable security tooling and deploy more attacker tools like Mimikatz that lets them move across the network and gain persistence.”
The zero-day patch that has received the most attention so far is CVE-2023-24932, which is a Secure Boot Security Feature Bypass flaw that is being actively exploited by “bootkit” malware known as “BlackLotus.” A bootkit is dangerous because it allows the attacker to load malicious software before the operating system even starts up.
According to Microsoft’s advisory, an attacker would need physical access or administrative rights to a target device, and could then install an affected boot policy. Microsoft gives this flaw a CVSS score of just 6.7, rating it as “Important.”
Adam Barnett, lead software engineer at Rapid7, said CVE-2023-24932 deserves a considerably higher threat score.
“Microsoft warns that an attacker who already has Administrator access to an unpatched asset could exploit CVE-2023-24932 without necessarily having physical access,” Barnett said. “Therefore, the relatively low CVSSv3 base score of 6.7 isn’t necessarily a reliable metric in this case.”
Barnett said Microsoft has provided a supplementary guidance article specifically calling out the threat posed by BlackLotus malware, which loads ahead of the operating system on compromised assets, and provides attackers with an array of powerful evasion, persistence, and Command & Control (C2) techniques, including deploying malicious kernel drivers, and disabling Microsoft Defender or Bitlocker.
“Administrators should be aware that additional actions are required beyond simply applying the patches,” Barnett advised. “The patch enables the configuration options necessary for protection, but administrators must apply changes to UEFI config after patching. The attack surface is not limited to physical assets, either; Windows assets running on some VMs, including Azure assets with Secure Boot enabled, also require these extra remediation steps for protection. Rapid7 has noted in the past that enabling Secure Boot is a foundational protection against driver-based attacks. Defenders ignore this vulnerability at their peril.”
In addition to the two zero-days fixed this month, Microsoft also patched five remote code execution (RCE) flaws in Windows, two of which have notably high CVSS scores.
CVE-2023-24941 affects the Windows Network File System, and can be exploited over the network by making an unauthenticated, specially crafted request. Microsoft’s advisory also includes mitigation advice. The CVSS for this vulnerability is 9.8 – the highest of all the flaws addressed this month.
Meanwhile, CVE-2023-28283 is a critical bug in the Windows Lightweight Directory Access Protocol (LDAP) that allows an unauthenticated attacker to execute malicious code on the vulnerable device. The CVSS for this vulnerability is 8.1, but Microsoft says exploiting the flaw may be tricky and unreliable for attackers.
Another vulnerability patched this month that was disclosed publicly before today (but not yet seen exploited in the wild) is CVE-2023-29325, a weakness in Microsoft Outlook and Explorer that can be exploited by attackers to remotely install malware. Microsoft says this vulnerability can be exploited merely by viewing a specially-crafted email in the Outlook Preview Pane.
“To help protect against this vulnerability, we recommend users read email messages in plain text format,” Microsoft’s writeup on CVE-2023-29325 advises.
“If an attacker were able to exploit this vulnerability, they would gain remote access to the victim’s account, where they could deploy additional malware,” Immersive’s Breen said. “This kind of exploit will be highly sought after by e-crime and ransomware groups where, if successfully weaponized, could be used to target hundreds of organizations with very little effort.”
For more details on the updates released today, check out roundups by Action1, Automox and Qualys, If today’s updates cause any stability or usability issues in Windows, AskWoody.com will likely have the lowdown on that.
Please consider backing up your data and/or imaging your system before applying any updates. And feel free to sound off in the comments if you experience any problems as a result of these patches.
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