Information Technology Services warned students via email to change their passwords in light of the Heartbleed bug, one of the Internet’s most damaging vulnerabilities.

The bug allows outside parties to access website users’ personal information — including passwords, usernames and emails — though it is not yet clear if criminals were aware of and used the bug prior to public knowledge of it.

James Fatz, NIU Information Security and Operations director, said 66 percent of the Internet could be affected by the bug, but it’s difficult to determine who has been infected. The bug has been around for about two years.

“Here at NIU, however, a scan has been done to 18 to 20 of the major systems, and the rest have not been checked for vulnerability,” Fatz said.

Fatz said people should create multiple, strong passwords instead of having a single password across their accounts.

“[Having multiple passwords] can enhance protection against the Heartbleed bug and prevent it from accessing many sources of personal information, whether it be e-mail, social media or online accounts,” Fatz said.

Freshman nutrition major Holly Smith said she doesn’t feel safe knowing there’s a bug.

“[Even though I don’t feel safe] I have different passwords for everything, so I don’t feel the need to change any,” Smith said.

Freshman psychology major John Sanchez said he didn’t know Heartbleed existed.

“Since I have the same password for relatively every Web service I use, I am going to change passwords …,” Sanchez said.

Information Technology Services encouraged the NIU community to change passwords to prevent personal information from being accessed by the bug.