It’s only been five days since Apple’s last security update for iOS, when dozens of serious security vulnerabilities were patched.
As we mentioned last week, the recent iOS 10.3 and macOS 10.12.4 updates included numerous fixes dealing with “arbitrary code execution with kernel privileges”.
Any exploit that lets an external attacker tell the operating system kernel itself what to is a serious concern that ought to be patched as soon as possible – hesitation is not an option.
After all, it’s the kernel that’s responsible for managing security in the rest of the system.
Take this analogy with pinch of salt, but an exploit that gives a remote attacker regular user access is like planting a spy in the Naval corps with a Lieutenant’s rank.
If you can grab local administrator access, that’s like boosting yourself straight to Captain or Commodore; but if you can own the kernel (this is not a pun), you’ve landed among the senior Admiral staff, right at the top of the command structure.
So make sure you don’t miss the latest we-didn’t-quite-get-this-one-out-last-time update to iOS 10.3.1:
iOS 10.3.1 Released April 3, 2017 Wi-Fi Available for: iPhone 5 and later, iPad 4th generation and later, iPod touch 6th generation and later Impact: An attacker within range may be able to execute arbitrary code on the Wi-Fi chip Description: A stack buffer overflow was addressed through improved input validation. CVE-2017-6975: Gal Beniamini of Google Project Zero
This is rather different from the usual sort of attack – the main CPU, operating system and installed apps are left well alone.
Most network attacks rely on security holes at a much higher level, in software components such as databases, web servers, email clients, browsers and browser plugins.
So, attacking the Wi-Fi network card itself might seem like small beer.
After all, the attacks that won hundreds of thousands of dollars at the recent Pwn2Own competition went after the heart of the operating system itself, to give the intruders what you might call an “access all areas” pass.
Nevertheless, the CPU of an externally-facing device like a Wi-Fi card is a cunning place to mount an attack.
It’s a bit like being just outside the castle walls, on what most security-minded insiders would consider the wrong side of the moat and drawbridge.
But with a bit of cunning you may be able to position yourself where you can eavesdrop on every message coming in and out of the castle…
…all the while being ignored along with the many unimportant-looking peasants and hangers-on who’ll never have the privilege of entering the castle itself.
Better yet, once you’ve eavesdropped on what you wanted to hear, you’re already on the outside, so you don’t have to run the gauntlet of the guards to get back out to a place where you can pass your message on.
What to do?
As far as we know, this isn’t a zero-day because it was responsibly disclosed and patched before anyone else found out about it.
Cybercrooks have a vague idea of where to start looking now the bug that has been described, but there’s a huge gap between knowing that an exploitable bug exists and rediscovering it independently.
We applied the update as soon as Apple’s notification email arrived (the download was under 30MB), and we’re happy to assume that we’ve therefore beaten even the most enthusiatic crooks to the punch this time.
You can accelerate your own patch by manually visiting Settings | General | Software Update to force an upgrade, rather than waiting for your turn in Apple’s autoupdate queue.