NASA routinely beams messages into the universe in an attempt to contact extraterrestrial intelligence. In more than 50 years of listening for a response, they've heard zilch. Which might be good. For even as NASA sends messages, some of its scientists wonder what it is they should say, and whether Earth should, indeed, keep putting out the proverbial welcome mat.
In "Would Contact with Extraterrestrials Benefit or Harm Humanity?", in Acta Astronautica, researchers from NASA and the University of Pennsylvania's Departments of Geography and Meteorology systematically analyze a broad range of contact scenarios, categorizing each one as beneficial, neutral, or harmful to humanity. Although the researchers do not perform quantitative analysis on the likelihood of the various scenarios, they do note that a relatively large number fall into the "harmful" category. Because of this, they recommend that Earth's messages to extraterrestrials be written more cautiously.
For example, we should stop sending "About Us" information that includes specifics about our DNA. (It could be used to design biological weapons against us.) Initial communication should be limited to mathematical discourse, and we should take care not to suggest that we want to colonize other planets. Nor should we broadcast that we are less than admirable stewards of the natural resources of our own planet. After all, we want to seem like the sort of neighbors a more advanced civilization would want to keep around.