Adobe has released an emergency update to address a critical security hole in its Flash Player browser plugin that is being actively exploited to deploy malicious software. If you’ve got Flash installed — and if you’re using Google Chrome or a recent version of Microsoft Windows you do — it’s time once again to make sure your copy of Flash is either patched, hobbled or removed.

In an advisory published today, Adobe said it is aware of a report that an exploit for the previously unknown Flash flaw — CVE-2018-5002 — exists in the wild, and “is being used in limited, targeted attacks against Windows users. These attacks leverage Microsoft Office documents with embedded malicious Flash Player content distributed via email.”

The vulnerable versions of Flash include v. 29.0.0.171 and earlier. The version of Flash released today brings the program to v. 30.0.0.113 for Windows, Mac, Linux and Chrome OS. Check out this link to detect the presence of Flash in your browser and the version number installed.

Both Internet Explorer/Edge on Windows 10 and Chrome should automatically prompt users to update Flash when newer versions are available. At the moment, however, I can’t see any signs yet that either Microsoft or Google has pushed out new updates to address the Flash flaw. I’ll update this post if that changes. (Update: June 8, 11:01 a.m. ET: Looks like the browser makers are starting to push this out. You may still need to restart your browser for the update to take effect.)

Adobe credits Chinese security firm Qihoo 360 with reporting the zero-day Flash flaw. Qihoo said in a blog post that the exploit was seen being used to target individuals and companies in Doha, Qatar, and is believed to be related to a nation-state backed cyber-espionage campaign that uses booby-trapped Office documents to deploy malware.

In February 2018, Adobe patched another zero-day Flash flaw that was tied to cyber espionage attacks launched by North Korean hackers.

Hopefully, most readers here have taken my longstanding advice to disable or at least hobble Flash, a buggy and insecure component that nonetheless ships by default with Google Chrome and Internet Explorer. More on that approach (as well as slightly less radical solutions) can be found in A Month Without Adobe Flash Player. The short version is that you can probably get by without Flash installed and not miss it at all.

For readers still unwilling to cut the Flash cord, there are half-measures that work almost as well. Fortunately, disabling Flash in Chrome is simple enough. Paste “chrome://settings/content” into a Chrome browser bar and then select “Flash” from the list of items. By default it should be set to “Ask first” before running Flash, although users also can disable Flash entirely here or whitelist/blacklist specific sites.

By default, Mozilla Firefox on Windows computers with Flash installed runs Flash in a “protected mode,” which prompts the user to decide if they want to enable the plugin before Flash content runs on a Web site.

Another, perhaps less elegant, alternative to wholesale kicking Flash to the curb is to keeping it installed in a browser that you don’t normally use, and then only using that browser on sites that require Flash.

Administrators have the ability to change Flash Player’s behavior when running on Internet Explorer on Windows 7 and below by prompting the user before playing Flash content. A guide on how to do that is here (PDF). Administrators may also consider implementing Protected View for Office. Protected View opens a file marked as potentially unsafe in Read-only mode.

Tags: Adobe Flash Player zero-day, CVE-2018-5002, Flash 30.0.0.113, Flash Player 29.0.0.171, Qihoo 360