Screenshot by Dan Ackerman/CNET

Open up Microsoft's Windows Phone Store and search for Super Mario, the classic Nintendo game series notoriously absent on mobile phones, and you'll find games using Nintendo's images, Nintendo's trademarks and perhaps an entire copy of the original video game.

There's just one problem: None of those apps is made or sanctioned by Nintendo.

Microsoft has a copyright issue, and it's not a new one. Its software storefronts have long been plagued by scams in the form of misleading apps and products that blatantly steal from well-known, popular and copyrighted TV shows, movies, music and games.

In April, CNET contacted Microsoft about this issue after finding a $5.99 app in the Windows Store that will illegally stream the hit HBO show "Game of Thrones." Microsoft, which said at the time that it takes intellectual property infringement seriously, removed the problematic Game of Thrones app. Others still exist.

Microsoft reiterated its position on intellectual property infringement when we contacted it for this story.

Microsoft

The world's largest software maker has said it's increasing enforcement of its app stores to to cull scammy apps that trick users into thinking they're downloading the real Spotify streaming music player, for example; knockoffs that take free services like Facebook's Messenger and slap price tags on them; and outright copyright infringers like the "Game of Thrones" program. But its enforcement efforts seem to be lagging behind the scammers', creating an embarrassing situation for Microsoft and undermining the credibility of its stores.

The situation comes at one of the most important moments in the software giant's history.

Microsoft's app stores will be a key part of its planned rollout for a new version of Windows, expected to be released sometime this summer. Windows 10, the first major Windows release under CEO Satya Nadella, is being touted as an overhaul of the operating system that promises better ways to perform tasks across various devices, a sleeker and more secure Web browser and a back-to-basics look and feel that marries the popular Windows 7 OS with more modern design.

To woo developers who may already be devoting most of their effort on apps for Apple's iOS software or Google's Android platform, Microsoft says apps built for Windows 10 can be modified to work on a smartphone, tablet or computer with relatively minimal effort. As part of its Windows revamp, Microsoft is combining two of the app stores it runs, one for smartphones and the other for PCs and tablets. That way, developers -- and consumers -- can view the Windows Store as a one-stop-shop for software that works everywhere.

But copyright-infringing apps could undermine the stores' integrity and create a confusing and sometimes predatory experience for users. To be sure, Microsoft isn't the only company to struggle with piracy and copyright issues. Apple, in its App Store, and Google, with its Google Play store, have also let software slip by that infringes on copyrights, violates their or another company's terms of service or otherwise makes finding app more difficult.

But the problem appears worse on the Windows Phone Store and on the general Windows Store for tablets and PCs. It's easy to find programs in Microsoft's app stores that illegally display hit shows like "Game of Thrones," "Breaking Bad" and "The Simpsons."

Another app called Freeflix helps users watch thousands of movies. The ad-supported app is free and borrows shamelessly from streaming service Netflix, paraphrasing its name and copying the red accent colors of its service and the look of its logo. The app offers pirated versions of films, including "Furious 7" and "Chappie," that hit theaters just two months ago. Excited fans can preorder the movies from retailers like Amazon.com or Apple's iTunes, or they can illegally watch right now using Freeflix to stream a copy from their PCs or mobile devices.

Screenshot by Dan Ackerman/CNET

The free version of Freeflix has more than 1,000 reviews and a five-star rating on Microsoft's store. An $8.99 version of the app, called Freeflix Pro, removes ads in the software.

Microsoft receives a 30 percent cut on all proceeds generated through apps downloaded from its Windows app stores.

The creator of Freeflix, a developer by the name of Tony Bits, can't be contacted through Microsoft's storefront. But Bits has created a dedicated website advertising Freeflix, which isn't available on Apple's App Store or the Google Play store. Attempts to speak with the owner of the website were unsuccessful at the time of publication.

The quest for developers

Microsoft's universal app store is key to its ambitious efforts for the next version of Windows. By 2018, the company hopes to have 1 billion devices running its software, and will rely on that single app store for downloading Windows programs.

Microsoft's app stores collectively contain only 500,000 apps, lagging far behind the more than 1.2 million apps designed for iOS and Android.

Microsoft hopes its one-software-that-runs-on-many devices approach will also help make its software for smartphones more popular. Android and iOS are the most popular mobile operating systems in the world, thanks to top top-selling smartphones and tablets from Samsung and Apple.

Andrew Hoyle/CNET

Though Windows runs on more than 90 percent of PCs in the world, Microsoft's Windows Phone software powers less than 3 percent of smartphones.

To help boost its market standing, Microsoft launched a campaign in March of 2013 that paid developers from $100, up to $2,000, for each app made for its platform. Though the campaign has since ended, the company continues to court app makers. At its annual Build developer conference last month, Microsoft announced tools for iOS and Android developers to more easily move their apps to the Windows platform, another incentive.

But Microsoft has had trouble convincing some top-tier app makers to offer their programs on Windows. Photo-sharing app Instagram wasn't available on Windows Phone until November 2013, three years after its release on Apple's iPhone. Meanwhile, Snapchat, a popular messaging service, has yet to release its app for Windows devices.

In its place, developers have created apps that plug into Snapchat's programming to replicate portions of its software. Microsoft has removed some copies at Snapchat's request.

Meanwhile, Google continues to withhold its Google Apps for Windows-powered devices after the two companies publicly fought two years ago over the use of ads and other features in the official Windows Phone app. Google Apps apps include the official YouTube video app and Google Maps.

Where does that leave Microsoft? Struggling to keep away bad apps that are taking advantage of the lack of policing from the company and a dearth of official software from popular companies.

"I have to think they're going to attempt to right the situation," said Brian Blau, an analyst with research firm Gartner. "I suspect Microsoft would rather have high quality apps than lots of them."

A slow fix

Microsoft began the cleanup process in August 2014 following a How-To Geek article calling its stores a "cesspool of scams."

Two weeks later, the company pledged to do a better job cracking down on misleading apps, or software that piggybacks off popular search terms such as "Firefox," the name of Mozilla's Web browser, and "VLC," the popular cross-platform video and music player. When people downloaded software with those labels, sometimes for as much as $10 each, what they got was apps that either weren't made by the companies -- or apps that didn't work.

Microsoft announced rules to cut down on copycats that established restrictions on naming and categorizing apps and detailing the type of logo developers can use to advertise their software. The company also removed more than 1,500 apps that didn't comply with the changes.

"The Store review is ongoing and we recognize that we have more work to do, but we're on it," said Todd Brix, Microsoft's general manager for Windows apps and stores, at the time. "We're applying additional resources to speed up the review process and identify more problem apps faster. No approach is perfect, so we encourage people to report any issues they may encounter with Windows Store."

Nine months later, the Windows Phone Store and standard Window Store look noticeably cleaner, with popular apps like Facebook, Netflix, Evernote and King.com's Candy Crush Saga puzzle game featured first on a search result page that's no longer filled with rows of knockoffs.

The Store review is ongoing and we recognize that we have more work to do, but we're on it. Todd Brix, Windows Store general manager

But a closer examination of the two app stores reveals that, while scams and knockoffs may be in decline, copyright-infringing apps remain easy to find. CNET started noticing the influx of these apps while reviewing Windows 8.1 computers such as the Microsoft Surface 3 and Acer Revo One . These lower-power PCs can benefit from applications optimized for Windows 8.1, which gives users more incentive to download software from Microsoft's store and not simply over the Internet.

Microsoft hasn't provided thorough details regarding how it approves apps for its stores. The company has said it has a team, not simply algorithms, who test and oversee apps. Microsoft also says it enforces its trademark and copyright guidelines, and that its certification process has a so-called content compliance period. That means Microsoft will withhold an app from being published for varying lengths of time "depending on how complex your app is, how much visual content it has, and how many apps have been submitted recently."

"We also conduct spot checks of apps after they've been published so we can identify potential problems. If we find any, you'll be notified about the issue and how to fix it," Microsoft advises in its guidelines.

Gaming apps: the worst offenders

Video games are an especially thorny area when it comes to copyright. It's impossible to protect certain game ideas from being ripped off by competitors, leading to clones, or closely copied reproductions of a game wrapped up in slightly different art.

In the case of Super Mario, a search for the phrase on Apple's App Store turns up apps like World 1-1, a clear reference to the way Nintendo names the playing levels in the game. The game itself has players control a pizza delivery boy running from aliens. Google fares worse, with a sprinkling of games using the Mario trademark in their name and some inventive titles like "Super Jario," but few if any contain anything resembling stolen art or other in-game material.

Screenshot by Nick Statt/CNET

In the Windows Phone Store, however, a search for Super Mario yields results like "Temple Dead Target: Spongebob Mario Pocket Epic." The free mobile game seems to contain numerous copyrighted items.

The app's publisher is listed as "Mine-craft," but attempts to get contact information for the company proved unsuccessful through any of Microsoft's channels. (The publisher is not be confused with Minecraft, the official pixel-art building game published by Swedish developer Mojang, which Microsoft purchased last fall.)

Other games can be found using similar naming schemes from the same developer, including "Despicable Me: Super Mario Surfers Pocket Edition," which contains copies of official Mario games that can be played from within the app. Other apps either use Mario in its title, use Nintendo art or are advertised directly as if they were the originals. One example: Super Mario RPG.

Nintendo has resisted releasing official versions of its games on mobile phones, choosing instead to partner with Japanese social gaming company DeNA to release titles based on its popular franchises in the coming years.

Nintendo did not immediately respond to requests for comment.

While these apps hurt the intellectual property of large corporations, smaller game developers are also suffering from Microsoft's lack of oversight. In February, independent developer Red Hook Studios used Twitter to inform fans that its latest game, Kickstarter-funded Darkest Dungeons, had been illegally copied and uploaded to the Windows Store.

The purported creator, listed as Balaji Chowdary, didn't include Red Hook Studios' name in the app description and asked $3.99 for the game. Red Hook Studios charges $20 to access its official version through a competing online marketplace run by Valve. It's unclear if customers who purchased Chowdary's knockoff were given access to the full version of the game or were simply victims of a scam.

If anyone has a contact at Windows Game Store, please share. Somebody is scamming DD by selling it (illegally) on there. — Red Hook Tyler (@tylersigman) February 22, 2015

Redhook filed a copyright infringement ticket through Microsoft, which reportedly began addressing the knockoff app immediately. It's no longer in the app store, nor is any other piece of software from Chowdary.

Though it was resolved fast, the incident is emblematic of the hurdles Microsoft may face as it strives to convince developers -- as small as Red Hook Studios and as large as Snapchat -- to prioritize for its platform. And if copyright holders can't rely on Microsoft to protect intellectual property, the universal Windows store won't ever come close to Apple's or Google's stores in market share or reputation.

If or when Microsoft begins a more widespread crackdown, it won't have to look hard for offenders.