Recently, I know Unfriend Alert as an app that can notify whenever someone removes me from his Facebook friend list. This interesting feature is used by many Facebook users. However, I cannot find any resource of this app and wonder whether it is published by Facebook or any other firm? Can Bkav give me more details?
Unfriend Alert is not published by Facebook but by a third party. When using Unfriend Alert, users' Facebook credentials will be stolen. Unfriend Alert is classified as a potentially unwanted program because it often displays unknown adware and tricks users into installing other free apps and malware when visiting websites via Chrome, Firefox and Internet Explorer. Moreover, users cannot block these advertisement or apps.
Unfriend Alert requires users' login credentials to activate the monitoring service and give unfriend notification to Facebook users. After logging, Unfriend Alert will send the login credentials to yougotunfriended.com (a domain owned by hackers).
Thus, if users downloaded this app, Bkav recommends removing Unfriend Alert and changing passwords as soon as possible. Besides, users should not provide Facebook password when using service or software of a third party in any case because Facebook provided API Oauth app (a sign-in system) for third parties. Users do not need to provide any log-in credentials.
Additionally, for your reference, you can learn how to prevent the risk of losing Facebook account at: How to prevent the risk of losing Facebook account.