This comes as a member of the HellCat ransomware group, known as Rey, gained access to a "non-critical application" belonging to a local branch in Romania.
After gaining access, the hacker had stolen 380,000 unique email addresses, source code, invoices, contracts and both customer and employee information, amounting to around 12,000 files, BleepingComputer claimed.
Despite this not being a ransomware attack, the attacker intended to extort the telecoms giant by leaving a ransom note.
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However, Orange did not engage in negotiations, leading the attacker to publish the stolen data on the dark web.
"Orange can confirm that our operations in Romania have been the target of a cyberattack," a company spokesperson said.
"We took immediate action, and our top priority remains protecting the data and interests of our employees, customers, and partners. There has been no impact on customers’ operations, and the breach was found to occur on a non-critical back office application."
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