Gigaset is a German manufacturer of telecommunications devices, including a series of smartphones running the Android operating system.
Starting on March 27, Gigaset users have reported their phones to repeatedly open browsers and displaying ads for mobile games.
After further inspection, users have found the unknown app 'easenf ', which would be reinstalled after being deleted.
According to German tech site BornCity, the easenf app was installed by the device's system update app, with the other malicious apps such as 'gem', 'smart', and 'xiaoan.'
Gigaset has confirmed that one of the company's servers has been compromised to push the malicious apps and has launched an investigation on this case.