An unidentified hacker has breached Bycyklen —Copenhagen's city bikes network— and deleted the organization's entire database, disabling the public's access to bicycles over the weekend.
The hack took place on the night between Friday, May 4, and Saturday, May 5, the organization said on its website.
Bycyklen described the hack as "rather primitive," alluding it may have been carried out "by a person with a great deal of knowledge of its IT infrastructure."
All of the organization's 1,860 bikes were down on Saturday morning as a result of the hack.
The affected bikes work together with an Android tablet that connects to the Bycyklen's database to record the details renting the bikes splayed across the city. Without the database, users weren't able to unlock bikes from their racks. Local users can also create accounts using their emails to unlock bikes faster.
Bycyklen said on Facebook that fixing the problem required a manual update of all bikes. Employees restored 200 bikes on Saturday after tracking down bicycles and rebooting the attached Android tablet.
The company said restoring all bikes to working order would "take some time."
In an update on its website published on Monday, Bycyklen said that after finishing an analysis of the attack, it did not find any signs of the hacker taking any data.
"The attack has been aimed directly at our business, not our users," the company said. "We do not store payment card information. The only information we keep is our users [sic] email addresses, phone numbers and their PIN codes for the Bycyklen bikes."
"For security purposes, we encourage all our users to change their PIN as soon as possible," the company said. Bycyklen is now holding a "treasure hunt" on its Facebook page, asking users to report non-working, so employees can update and restore them.
The hack came at a very inconvenient time, as Copenhagen is also hosting the Ice Hockey World Championship.