New Zero-Day Vulnerability Exposes Google Chrome Browser

On the 21/10/2020, Google released a stable channel update of Google Chrome desktop to patch several high-risk security issues which have been uncovered. Included in the patch release was a zero-day vulnerability which could be exploited by an attacker to hijack targeted computers.

Designation Threat Level Description
CVE-2020-15999 High Heap buffer overflow in FreeType
CVE-2020-16000 High Inappropriate implementation in Blink
CVE-2020-16001 High Use after free in media
CVE-2020-16002 High Use after free in PDFium
CVE-2020-16003 Medium Use after free in printing

CVE-2020-15999 relates to a type of memory corruption flaw called a heap buffer overflow. This corruption flaw was discovered in FreeType which is a commonly used open source software development library for rendering fonts that comes pre-packaged with Chrome.

Sergei Glazunov, a security researcher with Google Project Zero initially discovered and reported the flaw on the 19/10/2020. The zero-day vulnerability was also immediately reported to FreeType developers by Glazunov. FreeType developers developed an emergency patch on the 20/10/2020 to address the issue. This patch was released as FreeType 2.10.4.

While the team at Google’s Project Zero has only spotted an exploit targeting Google Chrome users, their technical lead Ben Hawkes warned on Twitter that other projects using FreeType might also be vulnerable. It is advised that anyone using FreeType in their projects should immediately deploy the fix included in FreeType version 2.10.4.


What should I do?

If you use Google Chrome or the open-source version of Chrome ‘Chromium’, you should check that your auto-updater is active and working and that you have the latest version installed. If you are not patched we highly recommend that you patch immediately.

To find out if you have the latest version installed you need to go to the ‘About Chrome’ or ‘About Chromium’ section of your browser. To get here you open Chrome or Chromium on your computer and click the(More) symbol in the top right hand corner. Just under the X (Window Close) button. This will produce a dropdown menu, from there click Help > About Google Chrome.

The current version number of your browser is the series of numbers which appear under the “Google Chrome” heading. You are looking for version number ‘86.0.4240.111’ this is the version number that was released on 21/10/2020 and available to all users.

However, there is a possibility you will see version number ‘86.0.4240.75’ or earlier when you open the About Chrome section. This means you are still on a previous version and your system hasn’t updated. Whilst on the ‘About Google’ page you will be able to check for updates or Chrome will inform you of any pending updates.

If you rarely close your browser at the end of the day before locking your device, now would be a good time to close down your browser and reopen it. This will give Chrome a chance to install the update. You should be able to spot a pending update by the presence of an upward arrow in a circle in the far right of your address bar.

For people using ‘Chromium’ (that’s the open-source version of Chrome), you should follow your usual update procedure, which will depend on the operating system you’re using and where you initially got Chromium.


Why should I install the update?

Updates are issued for a number of reasons, one of which is security. Most updates will include bug fixes which could expose your devices and infrastructure. It is good practice to ensure you all your devices and software applications are up-to-date as running old versions could increase your risk of a cyber attack.

In relation to this particular update, it is extremely important to install as it includes patches for five security bugs which were discovered.

Most crucially one of these bugs, recorded as CVE-2020-15999, is already known to attackers as the update notification states “Google is aware of reports that an exploit for CVE-2020-15999 exists in the wild”. This bug could pose an immediate threat to your devices which is why we advise installing this latest update as soon as possible.


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