The investigation revealed that WhatsApp was violating certain internationally accepted privacy principles, mainly in relation to the retention, safeguard, and disclosure of personal data. For example:
- In order to facilitate contact between application users, WhatsApp relies on a user's address book to populate subscribers' WhatsApp contacts list. Once users consent to the use of their address book, all phone numbers from the mobile device are transmitted to WhatsApp to assist in the identification of other WhatsApp users. Rather than deleting the mobile numbers of non-users, WhatsApp retains those numbers (in a hash form). This practice contravenes Canadian and Dutch privacy law which holds that information may only be retained for so long as it is required for the fulfilment of an identified purpose. Only iPhone users running iOS6 on their devices have the option of adding contacts manually rather than uploading the mobile address numbers of their address books to company servers automatically.
- At the time the investigation began, messages sent using WhatsApp's messenger service were unencrypted, leaving them prone to eavesdropping or interception, especially when sent through unprotected Wi-Fi networks. In September 2012, in partial response to our investigation, WhatsApp introduced encryption to its mobile messaging service.
- Over the course of the investigation, it was found that WhatsApp was generating passwords for message exchanges using device information that can be relatively easily exposed. This created the risk that a third party may send and receive messages in the name of users without their knowledge. WhatsApp has since strengthened its authentication process in the latest version of its app, using a more secure randomly generated key instead of generating passwords from MAC (Media Acess Control) or IMEI (International Mobile Station Equipment Identity) numbers (which uniquely identify each device on a network) to generate passwords for device to application message exchanges. Anyone who has downloaded WhatsApp, whether they are active users or not, should update to the latest version to benefit from this security upgrade.