Amazon has pulled all Blu phones from its global stores because the budget handsets come with preloaded spyware that sends private user data to China.
Kryptowire, a Virginia-based security firm, found that some of the devices are loaded with spying software from Chinese company Shanghai Adups Technology.
The software leaves users' phones vulnerable to remote hackers and having their text messages and call logs recorded, the experts found.
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Amazon has pulled all Blu phones from its global stores because the budget handsets come with preloaded spyware that sends private user data to China. Kryptowire first discovered the software because one of its researchers noticed unusual activity in his Blu R1 HD (pictured)
Security firm Kryptowire first discovered the software issue in November 2016.
One of its researchers bought the Blu R1 HD for a trip overseas when he noticed unusual network activity.
After analysts studied the phone for a week they saw it transmitting text messages to a server in Shanghai.
When the spyware feature was first discovered, Miami-based manufacturer Blu said 120,000 of its phones had been affected.
The firm announced it had updated the software to eliminate the feature.
The devices actively transmitted user and device information including 'the full-body of text messages, contact lists, call history with full telephone numbers' and identifiers, the company said.
Now Kryptowire has announced that some Blu phones still come with the spyware preloaded.
Amazon has since pulled all Blu phones from its global stores.
The software forces the phones to send all the device's text messages to a server in China every 72 hours.
It also allows other forms of discrete data collection, Kryptowire said.
The comments were made last week during the BlackHat security conference in Las Vegas.
Despite the security firm first warning of the issue in November 2016, Kryptowire said some handsets - including those sold on Amazon.com - are still preloaded with Chinese spyware.
'Because security and privacy of our customers is of the utmost