Microsoft Patch Tuesday, February 2023 Edition

Microsoft is sending the world a whole bunch of love today, in the form of patches to plug dozens of security holes in its Windows operating systems and other software. This year’s special Valentine’s Day Patch Tuesday includes fixes for a whopping three different “zero-day” vulnerabilities that are already being used in active attacks.

Microsoft’s security advisories are somewhat sparse with details about the zero-day bugs. Redmond flags CVE-2023-23376 as an “Important” elevation of privilege vulnerability in the Windows Common Log File System Driver, which is present in Windows 10 and 11 systems, as well as many server versions of Windows.

“Sadly, there’s just a little solid information about this privilege escalation,” said Dustin Childs, head of threat awareness at Trend Micro’s Zero Day Initiative. “Microsoft does note that the vulnerability would allow an attacker to exploit code as SYSTEM, which would allow them to completely take over a target. This is likely being chained with a remote code execution bug to spread malware or ransomware. Considering this was discovered by Microsoft’s Threat Intelligence Center, it could mean it was used by advanced threat actors. Either way, make sure you test and roll these fixes quickly.”

The zero-day CVE-2023-21715 is a weakness in Microsoft Office that Redmond describes as a “security feature bypass vulnerability.”

“Microsoft lists this as under active exploit, but they offer no info on how widespread these exploits may be,” Childs said. “Based on the write-up, it sounds more like a privilege escalation than a security feature bypass, but regardless, active attacks in a common enterprise application shouldn’t be ignored. It’s always alarming when a security feature is not just bypassed but exploited. Let’s hope the fix comprehensively addresses the problem.”

The third zero-day flaw already seeing exploitation is CVE-2023-21823, which is another elevation of privilege weakness — this one in the Microsoft Windows Graphic component. Researchers at cybersecurity forensics firm Mandiant were credited with reporting the bug.

Kevin Breen, director of cyber threat research at Immersive Labs, pointed out that the security bulletin for CVE-2023-21823 specifically calls out OneNote as being a vulnerable component for the vulnerability.

“In recent weeks, we have seen an increase in the use of OneNote files as part of targeted malware campaigns,” Breen said. “Patches for this are delivered via the app stores and not through the typical formats, so it’s important to double check your organization’s policies.”

Microsoft fixed another Office vulnerability in CVE-2023-21716, which is a Microsoft Word bug that can lead to remote code execution — even if a booby-trapped Word document is merely viewed in the preview pane of Microsoft Outlook. This security hole has a CVSS (severity) score of 9.8 out of a possible 10.

Microsoft also has more valentines for organizations that rely on Microsoft Exchange Server to handle email. Redmond patched three Exchange Server flaws (CVE-2023-21706, CVE-2023-21707, and CVE-2023-21529), all of which Microsoft says are remote code execution flaws that are likely to be exploited.

Microsoft said authentication is required to exploit these bugs, but then again threat groups that attack Exchange vulnerabilities also tend to phish targets for their Exchange credentials.

Microsoft isn’t alone in dropping fixes for scary, ill-described zero-day flaws. Apple on Feb. 13 released an update for iOS that resolves a zero-day vulnerability in Webkit, Apple’s open source browser engine. Johannes Ullrich at the SANS Internet Storm Center notes that in addition to the WebKit problem, Apple fixed a privilege escalation issue. Both flaws are fixed in iOS 16.3.1.

“This privilege escalation issue could be used to escape the browser sandbox and gain full system access after executing code via the WebKit vulnerability,” Ullrich warned.

On a lighter note (hopefully), Microsoft drove the final nail in the coffin for Internet Explorer 11 (IE11). According to Redmond, the out-of-support IE11 desktop application was permanently disabled on certain versions of Windows 10 on February 14, 2023 through a Microsoft Edge update.

“All remaining consumer and commercial devices that were not already redirected from IE11 to Microsoft Edge were redirected with the Microsoft Edge update. Users will be unable to reverse the change,” Microsoft explained. “Additionally, redirection from IE11 to Microsoft Edge will be included as part of all future Microsoft Edge updates. IE11 visual references, such as the IE11 icons on the Start Menu and taskbar, will be removed by the June 2023 Windows security update (“B” release) scheduled for June 13, 2023.”

For a more granular rundown on the updates released today, see the SANS Internet Storm Center roundup. 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.

Your Phone May Soon Replace Many of Your Passwords

Apple, Google and Microsoft announced this week they will soon support an approach to authentication that avoids passwords altogether, and instead requires users to merely unlock their smartphones to sign in to websites or online services. Experts say the changes should help defeat many types of phishing attacks and ease the overall password burden on Internet users, but caution that a true passwordless future may still be years away for most websites.

Image: Blog.google

The tech giants are part of an industry-led effort to replace passwords, which are easily forgotten, frequently stolen by malware and phishing schemes, or leaked and sold online in the wake of corporate data breaches.

Apple, Google and Microsoft are some of the more active contributors to a passwordless sign-in standard crafted by the FIDO (“Fast Identity Online”) Alliance and the World Wide Web Consortium (W3C), groups that have been working with hundreds of tech companies over the past decade to develop a new login standard that works the same way across multiple browsers and operating systems.

According to the FIDO Alliance, users will be able to sign in to websites through the same action that they take multiple times each day to unlock their devices — including a device PIN, or a biometric such as a fingerprint or face scan.

“This new approach protects against phishing and sign-in will be radically more secure when compared to passwords and legacy multi-factor technologies such as one-time passcodes sent over SMS,” the alliance wrote on May 5.

Sampath Srinivas, director of security authentication at Google and president of the FIDO Alliance, said that under the new system your phone will store a FIDO credential called a “passkey” which is used to unlock your online account.

“The passkey makes signing in far more secure, as it’s based on public key cryptography and is only shown to your online account when you unlock your phone,” Srinivas wrote. “To sign into a website on your computer, you’ll just need your phone nearby and you’ll simply be prompted to unlock it for access. Once you’ve done this, you won’t need your phone again and you can sign in by just unlocking your computer.”

As ZDNet notes, Apple, Google and Microsoft already support these passwordless standards (e.g. “Sign in with Google”), but users need to sign in at every website to use the passwordless functionality. Under this new system, users will be able to automatically access their passkey on many of their devices — without having to re-enroll every account — and use their mobile device to sign into an app or website on a nearby device.

Johannes Ullrich, dean of research for the SANS Technology Institute, called the announcement “by far the most promising effort to solve the authentication challenge.”

“The most important part of this standard is that it will not require users to buy a new device, but instead they may use devices they already own and know how to use as authenticators,” Ullrich said.

Steve Bellovin, a computer science professor at Columbia University and an early internet researcher and pioneer, called the passwordless effort a “huge advance” in authentication, but said it will take a very long time for many websites to catch up.

Bellovin and others say one potentially tricky scenario in this new passwordless authentication scheme is what happens when someone loses their mobile device, or their phone breaks and they can’t recall their iCloud password.

“I worry about people who can’t afford an extra device, or can’t easily replace a broken or stolen device,” Bellovin said. “I worry about forgotten password recovery for cloud accounts.”

Google says that even if you lose your phone, “your passkeys will securely sync to your new phone from cloud backup, allowing you to pick up right where your old device left off.”

Apple and Microsoft likewise have cloud backup solutions that customers using those platforms could use to recover from a lost mobile device. But Bellovin said much depends on how securely such cloud systems are administered.

“How easy is it to add another device’s public key to an account, without authorization?” Bellovin wondered. “I think their protocols make it impossible, but others disagree.”

Nicholas Weaver, a lecturer at the computer science department at University of California, Berkeley, said websites still have to have some recovery mechanism for the “you lost your phone and your password” scenario, which he described as “a really hard problem to do securely and already one of the biggest weaknesses in our current system.”

“If you forget the password and lose your phone and can recover it, now this is a huge target for attackers,” Weaver said in an email. “If you forget the password and lose your phone and CAN’T, well, now you’ve lost your authorization token that is used for logging in. It is going to have to be the latter. Apple has the infrastructure in place to support it (iCloud keychain), but it is unclear if Google does.”

Even so, he said, the overall FIDO approach has been a great tool for improving both security and usability.

“It is a really, really good step forward, and I’m delighted to see this,” Weaver said. “Taking advantage of the phone’s strong authentication of the phone owner (if you have a decent passcode) is quite nice. And at least for the iPhone you can make this robust even to phone compromise, as it is the secure enclave that would handle this and the secure enclave doesn’t trust the host operating system.”

The tech giants said the new passwordless capabilities will be enabled across Apple, Google and Microsoft platforms “over the course of the coming year.” But experts said it will likely take several more years for smaller web destinations to adopt the technology and ditch passwords altogether.

Recent research shows far too many people still reuse or recycle passwords (modifying the same password slightly), which presents an account takeover risk when those credentials eventually get exposed in a data breach. A report in March from cybersecurity firm SpyCloud found 64 percent of users reuse passwords for multiple accounts, and that 70 percent of credentials compromised in previous breaches are still in use.

A March 2022 white paper on the FIDO approach is available here (PDF). A FAQ on it is here.