DENVER -- The names and Social Security numbers of thousands of students at the University of Colorado Boulder have been exposed by a computer hacker, the university announced Tuesday.

A school official in Boulder say a computer worm attacked a computer server used by the College of Arts and Sciences. The hacker was then able to have access to the vital information for 45,000 students who were enrolled at CU Boulder from 2002 to the present.

IT security investigators said they do not believe the hacker who launched the worm was looking for personal data, but rather was attempting to take control of the machine to allow it to infiltrate other computers both on and off campus.

CU said a series of human and technical problems led to the security breach. All students whose information was exposed are being notified by letters sent to their homes.

The hack was discovered May 12. IT security investigators said that the worm entered the server through a vulnerability in its Symantec anti-virus software, which had not been properly patched by the IT staff at the Arts and Sciences Advising Center.

"The server's security settings were not properly configured and its sensitive data had not been fully protected," said Bobby Schnabel, CU-Boulder vice provost for technology. "Through a combination of human and technical errors, these personal data were exposed, although we have no evidence that they were extracted."

Students needing more information about protecting themselves, can visit a special Web site at click here.

The school said that it has instituted a new series of security measures, including:

Envelop the Arts and Sciences Advising Center IT operations and selected other CU Boulder IT operations under the control of the central ITS department, reducing the practice of distributing IT responsibilities among colleges, schools, academic departments and programs;

Continue to use see the latest software to identify and purge Social Security numbers from all CU Boulder computers in all departments. CU Boulder switched from Social Security numbers to a Student Identification number system in 2005.

Making available to campus IT administrators new host-intrusion detection software