Apple Updates Anti-Malware Definitions to Address Fake Flash Player Trojan

flash player trojan
Fake Flash Player trojan installer

While things have been relatively quiet on the malware front for OS X since a raid on Russian payment processing firm ChronoPay appeared to have taken down MacDefender nearly two months ago, one new trojan horse did pop up earlier this month. As detailed by F-Secure, the trojan known as "OSX.QHost.WB.A" masquerades as a Flash Player installer but actually adds entries to a computer's hosts file to redirect users attempting to visit certain Google sites.

Once installed, the trojan adds entries to the hosts file to hijack users visiting various Google sites (e.g., Google.com.tw, Google.com.tl, et cetera) to the IP address 91.224.160.26, which is located in Netherlands.

The server at the IP address displays a fake webpage designed to appear similar to the legitimate Google site.

Search results on the fake Google pages actually lead to pop-up windows that load external content which was broken at the time of discovery but presumably consisted of advertisements of some sort. While the threat as implemented at the time of discovery was relatively mild, inexperienced users falling for the trojan could find themselves unaware of what had happened to their systems and how to fix the hijacked routing added by the malware.

osx qhost wb a
Consequently, Apple earlier this week made its first significant addition to its "XProtect.plist" file since the spate of MacDefender variants surfaced in June. The XProtect.plist file contains malware definitions to enable users' systems to recognize and warn users of malicious downloads, a feature that debuted with Mac OS X Snow Leopard back in 2009.

The original anti-malware system required manual updates to account for new threats, and as such was updated only rarely by Apple as part of larger software updates. But with an Apple software update issued in response to the MacDefender threat earlier this year, Mac OS X systems are now able to make daily checks for updates to that file to ensure up-to-date protection against malware.

Popular Stories

AirPods Pro Firmware Feature

Apple Releases New Firmware for AirPods Pro 2, AirPods Pro 3, and AirPods 4

Thursday November 13, 2025 11:35 am PST by
Apple today released new firmware designed for the AirPods Pro 3, the AirPods 4, and the prior-generation AirPods Pro 2. The AirPods Pro 3 firmware is 8B25, while the AirPods Pro 2 and AirPods 4 firmware is 8B21, all up from the prior 8A358 firmware released in October. There's no word on what's include in the updated firmware, but the AirPods Pro 2, AirPods 4 with ANC, and AirPods Pro 3...
Tim Cook WWDC 2018

Report: Tim Cook to Step Down as Apple CEO 'as Soon as Next Year'

Saturday November 15, 2025 2:40 pm PST by
Apple is preparing for Tim Cook to step down as CEO of the company "as soon as next year," according to the Financial Times. The company's board of directors and senior executives "recently intensified preparations for Cook to hand over the reins," the report said. While the report said that Apple is unlikely to name a new CEO before its next earnings report in late January, it went on to ...
iPhone Pocket Short

iPhone Pocket Now Available to Order, But Already Selling Out

Friday November 14, 2025 6:20 am PST by
Apple recently teamed up with Japanese fashion brand ISSEY MIYAKE to create the iPhone Pocket, a limited-edition knitted accessory designed to carry an iPhone. iPhone Pocket is available to order on Apple's online store starting today, in the United States, France, China, Italy, Japan, Singapore, South Korea, and the United Kingdom. However, it is already completely sold out in the United...
apple silicon mac lineup 2024 feature purple m5

Apple's 2026 Mac Plans

Friday November 14, 2025 3:23 pm PST by
Most of Apple's Macs are slated to get M5 chips across 2026, and there's a possibility we'll even see the first M6 chips toward the end of the year. Updates are planned for everything from the MacBook Air to the Mac Studio. MacBook Air (Early 2026) The MacBook Air will be one of the first Macs to get a 2026 refresh, with an update planned for the first few months of the year. The MacBook...
best early black friday deals

Best Black Friday Apple Deals Live Now - Save on AirPods, iPads, and Apple Watches

Saturday November 15, 2025 1:45 pm PST by
We're officially in the month of Black Friday, which will take place on Friday, November 28 in 2025. As always, this will be the best time of the year to shop for great deals, including popular Apple products like AirPods, iPad, Apple Watch, and more. In this article, the majority of the discounts will be found on Amazon. Note: MacRumors is an affiliate partner with some of these vendors. When ...
tvOS 26 Profiles

tvOS 26.2 Adds a Useful New Feature to Your Apple TV

Friday November 14, 2025 10:02 am PST by
Starting with the upcoming tvOS 26.2 update, currently in beta, additional profiles created on the Apple TV no longer require their own Apple Account. In the Settings app on the Apple TV, under Profiles and Accounts, anyone can create a new profile by simply entering a name and indicating whether the profile is for a kid. The profile will be associated with the primary user's Apple Account,...
walmart new ornametns

Walmart Black Friday Deals Begin Today With Low Prices on Headphones, TVs, and More

Friday November 14, 2025 7:55 am PST by
Walmart's Black Friday sale has officially kicked off today, with an online shopping event that's also seeing some matching deals in retail locations. There are quite a few major discounts in this sale, including savings on headphones, TVs, and more. Note: MacRumors is an affiliate partner with Walmart. When you click a link and make a purchase, we may receive a small payment, which helps us...
CarPlay Pinned Messages

iOS 26.2 Adds New CarPlay Setting

Thursday November 13, 2025 6:48 am PST by
iOS 26 extended pinned conversations in the Messages app to CarPlay, for quick access to your most frequent chats. However, some drivers may prefer the classic view with a list of individual conversations only, and Apple now lets users choose. Apple released the second beta of iOS 26.2 this week, and it introduces a new CarPlay setting for turning off pinned conversations in the Messages...
iOS 26

Everything New in iOS 26.2 Beta 3

Monday November 17, 2025 3:20 pm PST by
Apple provided developers with the third beta of an upcoming iOS 26.2 update, and there are still new features that are being added with each beta that we get. We've rounded up all of the changes that Apple made in beta 3. AirDrop Apple added new AirDrop functionality, providing a way for two people to share files temporarily without having to add one another as contacts. iOS 26.2...

Top Rated Comments

KnightWRX Avatar
186 months ago
Let's get this out of the way right now : This is not an OS X virus.
Score: 36 Votes (Like | Disagree)
Stridder44 Avatar
186 months ago
Awesome, I was not aware that it updated daily.

And yes, this is not a virus. This is malware.
Score: 11 Votes (Like | Disagree)
longofest Avatar
186 months ago
No, it's not a "virus". It's a trojan. You think it's good, but its bad. (heh... depending on if you think "flash" is "good").

A question I have though, is under what conditions should ANY software modify the hosts file? Should Apple even allow programs that have been granted administrative rights to alter the hosts file? There is only a very limited benvolent use case for such an action, and that very related to what they did here: some anti-ad or anti-spyware utilities modify a host file to redirect known ad-producing domains to a "safe" domain. I personally think any modification of the host file should be given a warning like this:

The program _____ is trying to update a core Mac OS X system file that is used to provide network connectivity. While online advertisement blocking programs may require legitimate use of this file, most others applications may represent an attempt to install malicious software onto your computer. Are you sure you want to allow program _____ to modify this file?
Score: 9 Votes (Like | Disagree)
BC2009 Avatar
186 months ago
Funny.... I updated Flash yesterday on my kids' Mac mini and I thought that writing a Trojan that masquerades as an update to Flash would be brilliant since Flash is updated so often and getting prompted that you need to update Flash to view a website is very common..... And then today, here it is.
Score: 8 Votes (Like | Disagree)
Sjhonny Avatar
186 months ago
That's why you need to disable flash. :p

This has nothing to do with Flash.
Score: 8 Votes (Like | Disagree)
devilstrider Avatar
186 months ago
Been out of the loop for 10 weeks and MacRumors is getting my up to speed fast. I love this site.
Score: 8 Votes (Like | Disagree)