January 2, 2018

January 2, 2018.

Back to work after a few days off; New Year’s Day and whatnot.

What a year to start with some big computing news, which is not a good one. Tip of the hat to my colleague for forwarding me the article.

From the original article:

tl;dr: there is presently an embargoed security bug impacting apparently all contemporary CPU architectures that implement virtual memory, requiring hardware changes to fully resolve. Urgent development of a software mitigation is being done in the open and recently landed in the Linux kernel, and a similar mitigation began appearing in NT kernels in November. In the worst case the software fix causes huge slowdowns in typical workloads. There are hints the attack impacts common virtualization environments including Amazon EC2 and Google Compute Engine, and additional hints the exact attack may involve a new variant of Rowhammer. 



macOS High Sierra “root” User is Enabled by Default with Blank Password

Apple will be issuing Software Update to disable “root” user which is inadvertently enabled by default with blank password in macOS High Sierra.

To disable “root” user, follow the instruction from Apple or the instruction below:

Disable the root user
Choose Apple menu () > System Preferences, then click Users & Groups (or Accounts).

Click the Lock, then enter an administrator name and password.
Click Login Options.
Click Join (or Edit).
Click Open Directory Utility.
Click the Lock in the Directory Utility window, then enter an administrator name and password.
From the menu bar in Directory Utility: Choose Edit > Disable Root

In previous incarnations of macOS/OS X/Mac OS X, “root” user is disabled by default.

Anyone with physical access to your Mac potentially can reset your password.

Root Access Vulnerability in macOS High Sierra

As reported by Juli Clover for MacRumors and numerous other sites:

The bug, discovered by developer Lemi Ergin, lets anyone log into an admin account using the username “root” with no password. This works when attempting to access an administrator’s account on an unlocked Mac, and it also provides access at the login screen of a locked Mac.

We verified that on macOS High Sierra 10.13.1, “root” user is enabled by default with blank password. For comparison, OS X El Capitan has “root” user disabled by default.

We verified that previous versions of macOS/OS X/Mac OS X have “root” user disabled by default.

This is similar to the enabled-by-default-with-blank-password “administrator” accounts in Windows XP.

By having “root” user disabled by default, potentially a remote attacker can compromise Macs running macOS High Sierra.

Having said all that, anyone with physical access and the right knowledge can reset local user password.