Exfocus, an alleged hacker, posted a series of messages on Twitter before Monday's attack on Rutgers' computer network.
NEW BRUNSWICK -- An alleged hacker appeared to taunt Rutgers University officials Monday as a cyber attack paralyzed the school's computer network.
The university was hit with a "denial of service" attack Monday morning that crashed Rutgers' websites and cut off internet and wifi access to tens of thousands of students, faculty and employees.
An alleged hacker who uses the screen name Exfocus took credit for several similar attacks on Rutgers' computer networks during the 2014-2015 school year.
Several taunting tweets appeared on Exfocus' Twitter account Monday before and after the latest attack.
"where internet go?? 3m dollar gone?" read one tweet, posted around noon.
The tweets were later removed, but several students captured screen shots of Exfocus' Twitter page while the tweets were still visible to the public.
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The $3 million referenced in Exfocus' tweet appears to refer to the $3 million Rutgers officials recently said they plan to spend upgrading the university's cyber security system in reaction to the series of "denial of service" attacks over the last year.
The university also hired at least three consulting firms in recent months to help test its networks and upgrade its computer security.
In another tweet posted shortly before Monday's cyber attack began, Exfocus wrote "RIP rutgers cas 2k15."
The tweet appeared to refer to crashing Rutgers' Central Authentication Service, the site where Rutgers students and staff enter their identification names and passwords to access the university's networks.
It is unclear if Exfocus is responsible for the cyber attacks or an elaborate hoax. However, the taunting tweets appeared to begin shortly before the latest cyber attack began.
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A Rutgers spokesman said the university began to experience computer and internet problems early Monday.
"The Office of Information Technology is working to resolve the issue and we will inform the Rutgers community as soon as we have more information," said E.J. Miranda, a Rutgers spokesman.
The university's internet technology department identified the problem as a "denial of service event," or an attack in which a hacker uses "bots," or compromised computers, to flood a network with requests. The bots overwhelm the network, crashing websites and affecting internet access.
By Monday afternoon, Rutgers' websites and internet access appeared to be returning to normal.
The attack was at least the fifth "denial of service" attack at Rutgers since last fall.
The FBI was called in to investigate the earlier attacks. But neither FBI investigators nor Rutgers officials have commented on the case.
Exfocus appeared to taunt Rutgers on Twitter, Reddit and other social media sites during last spring's cyber attacks.
In an interview with a local tech blogger, a hacker claiming to be Exfocus said he or she was paid $500 an hour in Bitcoin by a client with a grudge against Rutgers.
"Normally I don't show myself, but the entity paying me has something against the school. They want me to 'make a splash,'" Exfocus said in the interview, according to a transcript posted by the tech blogger.
Though it remains unclear if Exfocus was responsible for Monday's internet outage and website disruptions, many Rutgers students directed their frustration at the alleged hacker's Twitter account (@ogexfocus).
"Please stop. There are graduate students, including myself, who need the Internet to do research that can't happen with this," one student wrote on Twitter.
Other students directed their anger at Rutgers officials, who said in July the university was raising tuition partly to help cover the rising cost of cyber security.
"Please tell me why my tuition was raised if @ogexfocus is still able to hack our internet," another student wrote in a tweet directed to Rutgers' Twitter account.
Rutgers hired three cyber security consultants -- FishNet Security, Level 3 Communications and Imperva - over the last year to do behind-the-scenes work to upgrade cyber security on campus.
The firms are doing a variety of work, including testing Rutgers' networks for possible areas vulnerable to hackers. Rutgers also paid Imperva $160,000 for specialized filters to help protect against denial of service attacks, according to records obtained through the state Open Public Records Act.
Kelly Heyboer may be reached at kheyboer@njadvancemedia.com. Follow her on Twitter @KellyHeyboer. Find NJ.com on Facebook.