Shard is a command-line tool that could be used by hackers to discover shared passwords between most popular web services, including Facebook, LinkedIn, Reddit, Twitter, or Instagram. The code of the Shard tool is available on GitHub, it is likely crooks will adapt it to make it works with other services, such as financial ones. Shard receives a username and password as input then it will attempt to authenticate with multiple sites. It is a powerful tool in the hackers hands.”]
Source: https://securityaffairs.co/wordpress/49353/hacking/shard-tool.html