Apple patches dangerous security holes, one in active use – update now!

Security

We’ve seen several news stories talking up some great new features in Apple’s latest software update for iOS, which was released yesterday.

However, we’re much more interested in the security patches that arrived in the update to iOS 14.6, because Apple fixed 38 significant bugs, covered by 43 different CVE bug numbers.

For what it’s worth, the update to macOS Big Sur 11.4 shared many of those bugs with iOS, as well as adding a raft of its own, with 58 significant bugs patched, covered by 73 different CVE bug numbers.

Perhaps even more importantly, one of the Big Sur bugs that was patched, now dubbed CVE-2021-30713, is a security flaw that is already known to criminals and has already and quietly been exploited in the wild.

In fact, this exploit was only recently reported to Apple after lurking unnoticed in Mac malware known as XCCSET that dates back to last year.

Ironically, this bug exists in a system component called TCC, short for Transparency Consent and Control, a part of macOS that is supposed to make sure that apps don’t do things they aren’t supposed to.

According to security researchers at Mac management software company Jamf, this bug provides a sneaky way for a simple AppleScript utility with no special permissions at all to “leech off” the permissions of an an already-installed app.

Usually, malware that blindly ran an AppleScript utility to record your screen would cause a giveaway security warning to pop up asking you if you wanted to let the malware go ahead.

Unless and until you clicked through into the Security & Privacy page in System Preferences, and manually approved the malware by adding it to the list of apps allowed to record your screen, the cybercrooks would be out of luck.

Jamf researchers, however, realised that by judiciously inserting the malicious screenshotting AppleScript utility into the application directory of software that already had Screen Recording permissions…

…they could then launch their AppleScript under the assumed authority of the so-called “donor” app and take screenshots covertly without any warnings popping up.

The researchers used Zoom as the “donor” app in their research article, but noted that the average Mac user is likely to have numerous screenshot-ready programs already installed, such as Discord, WhatsApp, Slack, WeChat, TeamViewer and many others. This trick is not limited to Screen Recording permissions, either, so other installed apps could be “piggybacked” too. This means that an attacker could invisibly acquire unauthorised access to other permissions such as Location Services, Photos, Camera, Microphone, and files and folders that would otherwise be off-limits.

Other potentially serious bugs that are shared between iOS/iPadOS and macOS, and therefore necessitate that you patch your iDevices as well as your Macs, include:

  • RCE bugs in the handling of audio, image and 3D-modelling files. RCE is short for remote code execution, and it typically denotes a security flaw that can be triggered by an attacker who simply sends you a file to look at, without needing to login to your system first. RCE bugs in handling image or audio files are particularly dangerous because those files are commonly used in web pages, where your browser reads them in and processes them automatically even if all you do is look at a website.
  • RCE, cross-site scripting and data leakage bugs in WebKit. Webkit is Apple’s core web browsing engine, used whenever you open the Safari browser. In fact,on mobile devices, Apple requires all browsers to use WebKit, even those that usually provide their own web engines. Additionally, WebKit is commonly used by non-browser apps as a convenient way of displaying rich content such as manuals and help files. As a result, RCE bugs in WebKit may have far-reaching consequences and can’t be sidestepped simply by avoiding the use of Safari.
  • RCE and data leakage bugs in the kernel. Getting unauthorised kernel-level access is one of the ultimate prizes in a hacking attack, for the simple reason that the kernel controls the rest of the system. This includes determining which programs get to run, regulating access to memory and devices such as the camera and microphone, deciding which programs are allowed to open what files, and even keeping control over the Administrator account (root on Apple systems) itself.
  • An RCE bug in Apple’s network security code. This bug apparently exists in Apple’s implementation of TLS, short for transport layer security, the protocol that makes HTTPS possible and puts the padlock in your browser’s address bar. Apple says simply that “processing a maliciously crafted certificate may lead to arbitrary code execution.” What this seems to mean is that simply by browsing to a URL that starts with https://, a booby-trapped server could trick your iPhone or Mac into installing malware right at the very start of the connection process, before any web content even shows up.

Big Sur also gets patches against a whole raft of serious bugs, including RCE, in the smbx software, which is installed on Macs so that they can connect to Microsoft networks. (The letters SMB are short for Server Message Block, the original name for Microsoft’s file sharing protocol.)

Apple’s mobile platforms don’t include Microsoft-compatible networking code, so they aren’t affected by the smbx bugs, but iOS does get a patch for a Wi-Fi bug dubbed CVE-2021-30667 and explained with the words: “an attacker in WiFi range may be able to force a client to use a less secure authentication mechanism.

We’re not sure what that means, but given that iPhones haven’t supported the old and insecure WEP protocol at all for many years, and that most iPhone wireless connections use WPA2…

…the only step down from there is “no encryption at all”.

What to do?

On iDevices, go to Settings > General > Software Update.

On a Mac, it’s Apple menu > System Preferences > Software Update.

If you’re already up to date, then the updater will say so; if not, it will offer you an immediate opportunity to catch up.

The latest versions to look out for at the time of this article [2021-05-25T12:00Z] are: iOS/iPadOS 14.6, watchOS 7.5 and macOS 11.4.

If you’re still using macOS 10.14 or 10.15 (Mojave or Catalina by name), you’ll be offered updates specific to those versions, and you’ll need to get Safari 14.1.1 as a separate update. (On Big Sur the new version of Safari is included in the main update.)

There isn’t an iOS 12 update this time, so that version stays at 12.5.3.

And, no, we didn’t forget our mantra: Patch early, patch often, because why be behind when you could be ahead?


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