I recently had to install the Viber app on my smartphone to get something from someone who did not have one of my conversation apps.
For those who know the application, the process is "simple". You enter your mobile number, a verification is done with a message, and immediately after the Viber application requests access to your contacts.
Here all good.
However, unlike other apps that only scan your contacts, Viber continues to scan and store the phone numbers of your contacts on its servers.
This may not all concern them, but I personally worried when I noticed the specific behavior of the company.
Perhaps it is no coincidence that the EFF Foundation does not mention the implementation at all Surveillance Self-Defense Guide.
Let us also mention that in its first edition Secure Messaging Scorecard (it has expired, but there is still for the file) the Viber application is one of the worst in security. EFF's new updated Surveillance Self-Defense Guide does not mention it at all.
How can you see that Viber stores your contacts on the servers it uses?
Very simple: Uninstall the application from your mobile device. Removing the application will also not remove your phone number from the contacts of other application users. Your friends will continue to see you in Viber's contacts, and they will be able to send you messages, although the app reports that the message was not delivered.
This practically means that your number continues to exist on the company's servers even after removing the app from your mobile device.
We can share the information we collect about you with the Viber family, including our parent company, Rakuten Inc., and its affiliates and affiliates (To learn more about Rakuten Inc. follow this link: http://global.rakuten.com/corp/about/).
Update: As you'll see in the comments below, the app has a setting to disable the account before removing it from the mobile device.
I add the "Update" because during my experimentation with the application I did not notice the above function.