Viber has slowly become more and more popular in recent times and was even
acquired by Rakuten earlier this year for almost a billion dollars. Going beyond mere mobiles, the service was also
expanded to desktops in 2013.
It appears that at some point, however, ESET's NOD32— the anti-virus software— began flagging Viber as a threat. Whenever a user would try to install Viber, NOD32 would return a pop-up saying that a "potential threat" has been found (with what NOD32 appears to suggest is a toolbar that Viber tries to install into IE) and asks the user whether or not the user would want to proceed.
This action appears to have annoyed the Viber team, prompting them to post an image of the pop-up with an overlay of "#EsetSucks" in big red text, alongside a tweet saying that the software is buggy and that users should uninstall it.