Steem Blockchain have several types of Bot, all of them have something in common, they are software that interact with Blockchain data. Some are Bid-Bot's, some scan the Blockchain for scam, plagiarism or copy content from internet, some comment posts with specific tag, etc., etc.

@noblebot

developed by @reazuliqbal have an interesting and noble job, scan the Blockchain data for passwords and private keys mistakenly typed by users in posts, comments or transfer memos, as happened to @tmarisco and others who were victims of @sami100 bot, @tmarisco for example made a mistake and typed active key on a transfer memo and @sami100 stole all the Steem and SBD she had at the time.

What does @noblebot

Scaning and finding passwords or private keys it analyzes the type of key and sends a warning to the owner or in case of being a key that could compromise the account when being used by a thief bot changes it and warns the key owner that the key was changed with instructions to the new key, the goal is change the key before @sami100 or other theif bot "smelling" the Blockchain data.

@noblebot was created 2 months ago and already found about 28 private keys and has succeeded in more than 50% of the occurrences, it saved about 175 SBD and 8,5 Steem to users.