Some app makers are cashing in on the end of Flappy Bird, but unfortunately without the knowledge of the users who download the game's replica.

According to the Los Angeles Times, Android market customers are especially vulnerable to the malware and should be cautious when downloading a Flappy Bird replica. Some install malware on the device that will incur charges on a user's phone bill without the customer knowing.

Trend Micro and Sophos, two security firms, said they have found multiple Flappy Bird alternatives to contain malware. They infect a user's phone by asking for more permission than the original Flappy Bird game did. For example, the original only asked for network access to run ads, but the clones asked for more and users who wanted to just play the game likely did not read what they agreed to.

The additional permissions eager users have granted include sending text messages, "drawing over other apps," making Internet bookmarks and more. Trend Micro said the clone can also distribute a user's phone number and email address, as well as sending texts to premium numbers, incurring charges.

The best ways to not risk getting malware on your device is to read what you grant permission to and only download from the Google Play app market.

Unfortunately for users who miss Flappy Bird, smartphones with app already installed have been removed from eBay, CNET reported.

"After reviewing your eBay account, it appears that you have not followed eBay's guidelines to list a device that can hold media or software," the company said in a statement.

"As a result... Listings have been removed," said the auction website. "Smartphones and tablets must be restored to factory settings before they are allowed to be sold on eBay. Please remove all content from your device, including the game Flappy Bird, before you attempt to list your item again. Please be sure your current and future listings follow these guidelines, keeping in mind that additional listing violations could result in the suspension of your account."

The game's creator Dong Nguyen told the Wall Street Journal earlier this week he decided to remove Flappy Bird due to intense attention to himself and the game. He also said he was being harassed for his decision to take down the game and said he was not comfortable with many people's apparent addiction to the game.