By spending just $50, you get a smartphone with fast data service, high-definition display, and to your astonishment, a secret feature: a preinstalled system that sends all your texts to China every 72 hours, reported The Daily Mail.

A Chinese manufacturer of a particular brand of smartphones has installed "backdoor" software on approximately 700 million Android phones, according to security contractors. The software monitors every activity of the user like where he goes, whom he talks to, and what he composes in his text messages. American authorities are not clear on whether this is a secret data gathering practice for advertising purposes or an effort by the Chinese government to compile intelligence.

The people who are most affected by this "backdoor" software are users of prepaid or disposable phones, including international customers. The software was written by Shanghai Adups Technology Company, a Chinese firm, which claims that its codes run on over 700 million phones, smart devices, and cars. BLU Products, a Miami-based manufacturer of phones, states that its phones numbering about 120,000 have been affected and that it had made some quick updates to discard the "backdoor" feature.

According to Kryptowire, the security company that revealed the vulnerability of the phone, the Adups software sent the entire contents of the text messages, call logs, location information, contact lists, and other important information to a Chinese server. Tom Karygiannis, vice president of Kryptowire, said the code is preinstalled on the phones and the users are not aware of the surveillance. The devices could be found at major online retailers in the U.S, like BestBuy, Amazon, etc. Adups has its presence all across the world with a market share of over 70 percent spread across 150 countries and has its offices in Shenzhen, Shanghai, Tokyo, Beijing, Miami, and New Delhi. Matt Apuzzo, who first reported the discovery, told the New York Times that the software was luckily not used on American phones.