Users of the 4chan online message board managed to get access to the online student information system used by a New Jersey school district after the school's administrative password was posted to 4chan last week.

The problem started last Tuesday, according to the Plainfield Board of Education, which serves a small school district just west of Newark. That's when somebody posted a link to the login page and the administrative username ("admin") and password ("poopnugget") of the district's Genesis Student Information System to 4chan, a popular but anarchic message board best known as the place where David Kernell posted details of his break-in of former Alaska Governor Sarah Palin's Yahoo e-mail account.

The Web-based Genesis software is used by about 160 New Jersey schools to manage their student records and communicate with students and parents.

It's not clear how much damage was caused, but 4chan members soon started posting screenshots showing how they were able to mess with the school's system. One screenshot shows school lunch prices reset to US$9,000 per meal. Another post claims that "every class is now an elective, and requires only 1 credit to graduate."

In another screenshot, it appears as though the 4chan intruder could have sent a message to students and parents using the school's emergency notification system, designed to send text messages and e-mails to parents in the event of a major disaster.

It's not clear whether the message went out, but if it did, parents in Plainfield would have received a technically accurate but tedious lecture on the difference between the Linux kernel and the GNU/Linux operating system.

The district's interim superintendent, Anna Belin-Pyles, confirmed the breach in a statement posted to the district's website on Saturday. There were "unauthorized breaches of one of the District's computer systems in an attempt to vandalize electronic data and to disrupt school district operations," she said.

Although some residents are worried that student records may have been tampered with, Belin-Pyles said that any damage to the system's data was, at worst, only temporary. "There has been no permanent damage to the electronic files and steps are being taken to remedy the situation and further secure the system," she wrote. The school district didn't return calls seeking comment for this story.

Genesis fixed the problem on Wednesday after discovering the stolen password, the company said. On Friday, Genesis posted a brief note offering customers some basic password protection tips.

A criminal investigation into the incident has been opened, Belin-Pyles said.

Robert McMillan covers computer security and general technology breaking news for The IDG News Service. Follow Robert on Twitter at @bobmcmillan. Robert's e-mail address is robert_mcmillan@idg.com