“As soon as we learned of the attack, we patched the vulnerability and closed the access the hacker had,” Zendesk announced. The attackers were able to download customer email addresses and subject lines of emails.
Earlier Friday, the Department of Homeland Security posted a warning about “ongoing malicious cyber activity” against the U.S. government, as well as many private enterprises. “The apparent objective of this activity has been the theft of intellectual property,” the warning said. Other data sought includes intellectual property, trade secrets and sensitive business information.
The department urged network administrators to contact it for more information. The posting came after computer security specialist Mandiant, a contractor to New York Times Co. (NYSE:NYT), published a report linking a unit of China's People's Liberation Army to cyberattacks on U.S. sites.
The website also said it was “working with authorities to bring anyone involved to justice.”
Separately, Twitter, Tumblr and Pinterest notified customers of the attacks. The sites said they didn’t believe other confidential data like passwords had been compromised, although some phone numbers may have been accessed.
Zendesk’s announcement comes in a week when major consumer sites including Facebook (NASDAQ:FB) have acknowledged cyberattacks. Others, including Apple Inc. (NASDAQ:AAPL) and Google Inc. (NASDAQ:GOOG) have reported being cyber targets as well.
Apple released a patch late Thursday for its Java OS X Lion and other software. Google released a patch to Google Chrome that it said could handle vulnerabilities.
Zendesk was established in Denmark in 2007 by programmers headed by CEO Mikkel Svane seeking to offer one of the first cloud-based services.
Last year it raised $60 million in new venture capital from Redpoint Ventures, Index Ventures, Matrix Partners, Charles River Ventures and Benchmark Capital and GGV Capital as well as from Goldman Sachs (NYSE:GS). It took in $6 million in initial funding in 2009 from Benchmark and Charles River.



![Miss USA 2013: Meet The 51 Contestants Competing In The Beauty Pageant [PHOTOS] Miss USA 2013: Meet The 51 Contestants Competing In The Beauty Pageant [PHOTOS]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_multimedia/public/2013/06/13/miss-usa-contestants_14.jpg)


![Stephen Hester Ousted As Royal Bank Of Scotland (RBS) CEO Following Bank's Talks With UK Treasury [VIDEO] Stephen Hester Ousted As Royal Bank Of Scotland (RBS) CEO Following Bank's Talks With UK Treasury [VIDEO]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_medium/public/2013/06/12/rtr3dngo.jpg)
![Hong Kong House Prices Shoot Up, Greek House Prices Plummet [MAP] Hong Kong House Prices Shoot Up, Greek House Prices Plummet [MAP]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_medium/public/2013/06/11/knight-rank-house-prices.png)


![Turkish Riot Police Enter Taksim Square: Riot Police Clash With Protesters In Attempt To Break Up Protests [PHOTOS] Turkish Riot Police Enter Taksim Square: Riot Police Clash With Protesters In Attempt To Break Up Protests [PHOTOS]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_medium/public/2013/06/11/protester-taking-cover.jpg)
![Flooding In Europe: Floods In Germany, Austria, The Czech Republic, Hungary And Slovakia In Pictures [PHOTOS] Flooding In Europe: Floods In Germany, Austria, The Czech Republic, Hungary And Slovakia In Pictures [PHOTOS]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_medium/public/2013/06/11/flooding-europe-billboard.jpg)
![Robin Thicke Credits Justin Timberlake For Success Of Chart Topping Single 'Blurred Lines' [VIDEO] Robin Thicke Credits Justin Timberlake For Success Of Chart Topping Single 'Blurred Lines' [VIDEO]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_multimedia/public/2011/11/21/193689-singer-robin-thicke-poses-backstage-at-the-2011-american-music-awards-.jpg)











![Apple iOS 7: New Features Dazzle At WWDC 2013, Designed To 'Bring Order To Complexity' [PHOTOS] Apple iOS 7: New Features Dazzle At WWDC 2013, Designed To 'Bring Order To Complexity' [PHOTOS]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_small/public/2013/06/10/iphone5-ios-7.jpg)

![Unpaid Intern Lawsuit Against Atlantic Records And Warner Music Group Tests Legality Of Music Industry Internships [EXCLUSIVE] Unpaid Intern Lawsuit Against Atlantic Records And Warner Music Group Tests Legality Of Music Industry Internships [EXCLUSIVE]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_small/public/2013/06/17/wmg.jpg)


![VIDEO USA 1 - 0 Honduras: Highlights Of The Americans Win Over Honduras Behind Altidore's Goal [World Cup Qualifying - Brazil 2014] VIDEO USA 1 - 0 Honduras: Highlights Of The Americans Win Over Honduras Behind Altidore's Goal [World Cup Qualifying - Brazil 2014]](http://s1.ibtimes.com/sites/www.ibtimes.com/files/styles/v2_small/public/2013/06/19/jozy.jpg)


Like or Follow us for updates on the biggest stories!