New 'Yontoo' Adware Trojan Targets Major Browsers on OS X

Russian security firm Doctor Web this week highlighted a new trojan (via The Next Web) affecting OS X systems and which installs an adware plug-in capable of injecting ads into users' browsing experience.

As with other trojans, this new Yontoo malware relies on tricking users into installing the package, which in this case masquerades as a movie trailer video plug-in, download accelerator, or other software a user might believe they want or need on their system.

When launched, Trojan.Yontoo.1 displays a dialogue window that asks the user if they want to install Free Twit Tube.

However, after the user presses ‘Continue’, instead of the promised program, the Trojan downloads (from the Internet) and installs the plugin Yontoo for Safari, Chrome and Firefox. These browsers are most popular among Mac OS X users. While a user surfs the web, the plugin transmits information about the loaded pages to a remote server.

In return, it gets a file that enables the Trojan to embed third-party code into pages visited by the user.

As an example of Yontoo's capabilities, Doctor Web shows how ads can be injected into apple.com once the plug-in has been unwittingly installed by the user.

apple_com_adware
Compared to Windows, OS X has long been a relatively unpopular target for malware authors, but attacks targeting Apple customers have been on the rise. Many of the most highly publicized attacks come via trojans that rely on tricking users into granting installation privileges, while third-party platforms such as Java have also frequently been used to inject code into Mac systems.

Apple has been increasing its efforts to fight malware, introducing a rudimentary anti-malware functionality in OS X Snow Leopard and an enhanced Gatekeeper system in OS X Mountain Lion. Apple has also increasingly been blocking vulnerable versions of Java until Oracle is able to release patched versions of its plug-ins.

Popular Stories

Beyond iPhone 13 Better Triad

Apple's 20th Anniversary iPhone May Finally Go All Screen

Tuesday April 15, 2025 6:31 am PDT by
Apple is preparing a "bold" new iPhone Pro model for the iPhone's 20th anniversary in 2027, according to Bloomberg's Mark Gurman. As part of what's being described as a "major shake-up," Apple is said to be developing a design that makes more extensive use of glass – and this could point directly to the display itself. Here's the case for Apple releasing a truly all-screen iPhone with no...
maxresdefault

iPhone 17 Pro Launching Later This Year With These 12 New Features

Sunday April 13, 2025 7:52 am PDT by
While the iPhone 17 Pro and iPhone 17 Pro Max are not expected to launch until September, there are already plenty of rumors about the devices. Subscribe to the MacRumors YouTube channel for more videos. Below, we recap key changes rumored for the iPhone 17 Pro models as of April 2025: Aluminum frame: iPhone 17 Pro models are rumored to have an aluminum frame, whereas the iPhone 15 Pro and ...
iOS 19 Roundup Feature

iOS 19 Will Add These New Features to Your iPhone

Tuesday April 15, 2025 7:37 am PDT by
The first iOS 19 beta is less than two months away, and there are already a handful of new features that are expected with the update. Apple should release the first iOS 19 beta to developers immediately following the WWDC 2025 keynote, which is scheduled for Monday, June 9. Following beta testing, the update should be released to the general public in September. Below, we recap the key...
CarPlay Hero

Apple Releases Wireless CarPlay Fix

Wednesday April 16, 2025 11:28 am PDT by
If you have been experiencing issues with wireless CarPlay in your vehicle lately, it was likely due to a software bug that has now been fixed. Apple released iOS 18.4.1 today, and the update's release notes say it "addresses a rare issue that prevents wireless CarPlay connection in certain vehicles." If wireless CarPlay was acting up for you, updating your iPhone to iOS 18.4.1 should...
iphone 16 pro models 1

17 Reasons to Wait for the iPhone 17

Thursday April 17, 2025 4:12 am PDT by
Apple's iPhone development roadmap runs several years into the future and the company is continually working with suppliers on several successive iPhone models simultaneously, which is why we often get rumored features months ahead of launch. The iPhone 17 series is no different, and we already have a good idea of what to expect from Apple's 2025 smartphone lineup. If you skipped the iPhone...
Apple 2025 Thumb 1

10 Products Still Coming From Apple in 2025

Friday April 11, 2025 4:14 pm PDT by
Apple may have updated several iPads and Macs late last year and early this year, but there are still multiple new devices that we're looking forward to seeing in 2025. Most will come in September or October, but there could be a few surprises before then. We've rounded up a list of everything that we're still waiting to see from Apple in 2025. iPhone 17, 17 Air, and 17 Pro - We get...
AirPods Pro 3 Mock Feature

AirPods Pro 3 Just Months Away – Here's What We Know

Friday April 18, 2025 5:16 am PDT by
Despite being more than two years old, Apple's AirPods Pro 2 still dominate the premium wireless‑earbud space, thanks to a potent mix of top‑tier audio, class‑leading noise cancellation, and Apple's habit of delivering major new features through software updates. With AirPods Pro 3 widely expected to arrive in 2025, prospective buyers now face a familiar dilemma: snap up the proven...
iOS 18

Apple Releases iOS 18.4.1 With Bug Fixes

Wednesday April 16, 2025 10:11 am PDT by
Apple today released iOS 18.4.1 and iPadOS 18.4.1, minor updates to the iOS 18 and iPadOS 18 operating systems that came out last September. iOS 18.4.1 and iPadOS 18.4.1 come two weeks after the launch of iOS 18.4 and iPadOS 18.4. The new software can be downloaded on eligible iPhones and iPads over-the-air by going to Settings > General > Software Update. There have been complaints about ...
iPhone 6s MacRumors YouTube

Apple Says These Products Are Now Vintage

Tuesday April 15, 2025 9:53 am PDT by
Apple today updated its vintage products list to add the 2018 Mac mini and the iPhone 6s, devices that will get more limited service and repairs now that they are considered vintage. The iPhone 6s initially launched in 2015, but Apple kept it around as a low-cost device until 2018, which is why it is only now being added to the vintage list. The iPhone 6s had Apple's A9 chip, and it was...

Top Rated Comments

Slix Avatar
158 months ago
Want to install Free Twit Tube?

Seems legit. :rolleyes:
Score: 20 Votes (Like | Disagree)
litmag01 Avatar
158 months ago
Say YES to everything unless it asks to continue.

In that case, press CONTINUE and enter bank account number, routing number and any pertinant passwords.
Score: 18 Votes (Like | Disagree)
anzio Avatar
158 months ago
It's times like this that I'm glad that OS X has XProtect.

Oh yeah. And I'm happy I also wield common sense. :)
Score: 14 Votes (Like | Disagree)
Pechente Avatar
158 months ago
Wow, a user can be tricked to actively install harmful software - a serious flaw in OS X!
Score: 11 Votes (Like | Disagree)
Apple_Robert Avatar
158 months ago
Macs were never as secure as PCs but they were unpopular enough that nobody bothered to attempt to exploit them. Now it seems that every other day there's another massive security flaw found in Mac OS X.

What security flaw are you referring to with this story?
Score: 9 Votes (Like | Disagree)
vmistery Avatar
158 months ago
Macs were never as secure as PCs but they were unpopular enough that nobody bothered to attempt to exploit them. Now it seems that every other day there's another massive security flaw found in Mac OS X.

You missed patch Tuesday then?
Score: 9 Votes (Like | Disagree)