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Yes Chrome is scanning your Windows PC, but it might be a bug

A few days ago Kelly Shortridge, a product manager at SecurityScorecard detected some unexpected behavior on her PC, as a honeypot Canarytoken reported being accessed by Chrome.exe. That’s not what you’d expect from a web browser normally, except for one thing — Google did add some antivirus-y capabilities to its browser on Windows late last year as an enhancement to its Chrome Cleanup tool that can help reset hijacked settings. Google Chrome security lead Justin Schuh explained how the feature works and pointed to some documentation about it, and that was that —

If you are hitting this issue and you want a fix right now then go to chrome://downloads in your browser, go to the menu in the top right, and select Clear All. That will clear Chrome’s list of downloaded files so that it won’t have any files to existence-check at startup. If you have a large list of downloaded files then this will improve startup time slightly.

It turns out the “AV scanning” wasn’t that at all, and what it was doing could affect you right now. It turns out that Chrome is checking the integrity of downloaded files at startup, and a bug lead it to that particular folder. It relies on the Downloaded History list for this check, and if you have a lot of files in there, it could slow down your computer when you start Chrome. While the dev team is working to skip the check entirely in a future update, users worried about it can fix it by clearing their download history.

macOS High Sierra Bug Lets Anyone Gain Root Access Without a Password

If you own a Mac computer and run the latest version of Apple’s operating system, macOS High Sierra, then you need to be extra careful with your computer.

A serious, yet stupid vulnerability has been discovered in macOS High Sierra that allows untrusted users to quickly gain unfettered administrative (or root) control on your Mac without any password or security check, potentially leaving your data at risk.

Discovered by developer Lemi Orhan Ergin on Tuesday, the vulnerability only requires anyone with physical access to the target macOS machine to enter “root” into the username field, leave the password blank, and hit the Enter a few times—and Voila!

In simple words, the flaw allows an unauthorized user that gets physical access on a target computer to immediately gain the highest level of access to the computer, known as “root,” without actually typing any password.

Needless to say, this blindingly easy Mac exploit really scary stuff.

This vulnerability is similar to one Apple patched last month, which affected encrypted volumes using APFS wherein the password hint section was showing the actual password of the user in the plain text.

Here’s How to Login as Root User Without a Password

If you own a Mac and want to try this exploit, follow these steps from admin or guest account:

  • Open System Preferences on the machine.
  • Select Users & Groups.
  • Click the lock icon to make changes.
  • Enter “root” in the username field of a login window.
  • Move the cursor into the Password field and hit enter button there few times, leaving it blank.

With that (after a few tries in some cases) macOS High Sierra logs the unauthorized user in with root privileges, allowing the user to access your Mac as a “superuser” with permission to read and write to system files, including those in other macOS accounts as well.

This flaw can be exploited in several ways, depending on the setup of the targeted Mac. With full-disk encryption disabled, a rogue user can turn on a Mac that’s entirely powered down and log in as root by doing the same trick.

At Mac’s login screen, an untrusted user can also use the root trick to gain access to a Mac that has FileVault turned on to make unauthorized changes to the Mac System Preferences, like disabling FileVault.

All the untrusted user needs to do is click “Other” at the login screen, and then enter “root” again with no password.

However, it is impossible to exploit this vulnerability when a Mac machine is turned on, and the screen is protected with a password.

Ergin publicly contacted Apple Support to ask about the issue he discovered. Apple is reportedly working on a fix.

“We are working on a software update to address this issue. In the meantime, setting a root password prevents unauthorized access to your Mac. To enable the Root User and set a password, please follow the instructions here: https://support.apple.com/en-us/HT204012. If a Root User is already enabled, to ensure a blank password is not set, please follow the instructions from the ‘Change the root password’ section.”

Here’s How to Temporarily Fix the macOS High Sierra Bug

Fortunately, the developer suggested a temporary fix for this issue which is as easy as its exploit.

To fix the vulnerability, you need to enable the root user with a password. Heres how to do that:

  • Open System Preferences and Select Users & Groups
  • Click on the lock icon and Enter your administrator name and password there
  • Click on “Login Options” and select “Join” at the bottom of the screen
  • Select “Open Directory Utility”
  • Click on the lock icon to make changes and type your username and password there
  • Click “Edit” at the top of the menu bar
  • Select “Enable Root User” and set a password for the root user account

This password will prevent the account from being accessed with a blank password.

Just to be on the safer side, you can also disable Guest accounts on your Mac. for this, head on to System Preferences → Users & Groups, select Guest User after entering your admin password, and disable “Allow guests to log in to this computer.”