Kansas University officials said Thursday they believed the "hole" that allowed a computer hacker to download personal information about 1,450 of the school's international students has been patched.
"While no one can guarantee the absolute security of electronic data, I am confident that we have closed the temporary 'hole' in our system, which occurred while we were enhancing our computer security," said KU Chancellor Robert Hemenway.
Concern over national security makes identifying the hacker who downloaded the information a top priority, FBI agents said Thursday.
Agents are calling the incident the most serious and potentially dangerous hacking crime in the Midwest.
"Due to the sensitivity of the information, it's at the top of the list right now as far as computer crime investigations," said Special Agent Jeff Lanza.
Officals at Immigration and Naturalization Services were stunned by the crime.
"I thought I'd seen it all," said Mike Heston, director of the immigration service office in Kansas City, Mo. "I've never heard of something at this scale. We're concerned about this. It has fraudulent implications for national security."
Meanwhile, students were attempting to find ways to guard against their personal information being used for financial gain or illegal entry into the United States.
"There could be 100 different ways, all up to my imagination, for how they could use that," said Arun Agarwal, a graduate student from India.
KU officials discovered about noon Wednesday that a hacker had downloaded personal information -- including Social Security numbers and passport numbers -- of about 1,450 students, most of them from other countries.
The breach occurred Jan. 17, though the hacker had used the server to distribute copyrighted movies and pornography four other times beginning Jan. 6.
The hacker breached a "hole" in KU's security system that was caused during an upgrade in security on the server. The server that was hacked was in Academic Computing Services, which houses network equipment and offices for KU's computer workers, said Marilu Goodyear, vice provost for information services.
Lanza said two agents from the FBI, which investigates computer crimes, began an investigation Thursday. He said he didn't know how long the investigation would continue.
"I can't talk about the specifics," he said. "But KU's completely cooperating with retrieving information from its computer logs to track down the hacker. Our goal is to determine whether that database was specifically targeted. That will help determine the motivation for why this happened."
Goodyear said the Immigration and Naturalization Service on Wednesday notified all ports of entry into the United States about the computer hacker. KU students entering or leaving the country could face additional questioning.
Mike Heston, director of the Kansas City, Mo., INS office, declined to comment, citing the FBI's lead role in the case.
"We're doing things, but we can't talk about it because it's somebody else's case," he said.
The student information was contained in test files KU had gathered to comply with the Student and Exchange Visitor Information System, or SEVIS, which will allow universities to transmit information on foreign students to the INS.
Some information must be reported beginning today, though most of the system won't be online until August.
KU officials and students, who were first notified of the breach by e-mail Wednesday evening, were taking steps to minimize the possible effects of the incident.
Administrators on Thursday sent an e-mail to students recommending they contact the fraud departments of the three major credit bureaus to have a "fraud alert" placed on their files and prohibit pre-approved credit cards from being activated in their names.
The e-mail also provided phone numbers for agencies that could assist if students suspected their information was being used by someone illegally.
But officials admitted there wasn't much they could do until more was known about who downloaded the data.
"Hopefully no one will be damaged or suffer losses because of this," said Joe Potts, director of the Office of International Student and Scholar Services. "At this time, we have no way of knowing whether that will happen."
Several students said they felt helpless in the situation. Luis Parreira, a senior from Brazil, said he wasn't sure how officials at the border could prove his identity.
"I don't know how they're going to know I'm Luis and not just somebody with the same information," he said. "There isn't anything to do right now. They have my Social Security number, my passport number, my phone number and my e-mail all in that database. I'm not sure if they want to use that against me."
Agarwal said he was concerned about some international students who hadn't returned for the spring semester.
"They have no clue what has happened, how this information leaked out," he said.
Janet Murguia, executive vice chancellor for university relations, said KU was taking the incident "very seriously" because of concern over international terrorism.
"We know what environment we're in," she said. "We don't want to create a false sense of alarm here, but we want to make sure students are protected."
Associated Press and Knight Ridder Newspapers contributed to this report.