The Massachusetts Bay Transit Authority sent out an e-mail to all of its employees, requesting that everyone should remain vigilent when it comes to security issues.

The confidential e-mail was obtained by the Globe and the agency’s concerns are closely linked to the recent incident with the three MIT students who released, during last week’s Defcon hacker convention, the details needed to hack into the agency’s system.

The MBTA requested all computer users inside the agency to "be aware of the possibility of malicious activity aimed at MBTA Information Technology (IT) assets and resources."

Yesterday, a federal judge demanded Zack Anderson, Alessandro Chiesa, and R.J. Ryan, the three Massachusetts Institute of Technology students to prepare a paper with more details about the flaws found in the MBTA’s system.

During the convention, the students announced an 87 slide presentation that would have included their research on several security flaws in MBTA’s system, flaws which allowed them to hack into the company’s CharlieCard and Charlie Ticket and offer people free subway rides.

Even though, in an effort to keep the information secured, the authorities stopped the event from happening, according to the students, their presentation was available on MIT’s Web site for several months and it was also included on the conference’s presentation CD.

The Electronic Frontier Foundation (EFF) is representing the students, claiming that the data was already out in the open and that the court’s restraint is unconstitutional and extremely unnecessary.

"The students have done everything they need to do and more, and still they don't have their free-speech rights," said EFF spokeswoman Rebecca Jeschke, as quoted by the Associated Press. She also added that the group will surely appeal the decision.