Executive search company Korn/Ferry International Inc said its computer network had been hacked, making it the latest in a list of firms that have been the target of sophisticated cyber attacks in recent months.
Korn/Ferry said it had taken steps to contain the impact of the breach and was investigating the source of the attack.
The company, which has offices in 40 countries, said the intrusion falls in the category of an "advanced persistent threat", a term used to describe cyber attacks that employ sophisticated techniques and tools to access databases.
Cybersecurity has become a major focus area for policy makers with intelligence agencies and internet security firms warning of the likelihood of more damaging attacks on banks, utilities and stock exchanges.
Reuters reported last month that Iranian hackers had repeatedly attacked Bank of America Corp, JPMorgan Chase & Co and Citigroup Inc over the past year as part of a broad cyber campaign.
Professional networking site LinkedIn and online dating service eHarmony said in June that some user passwords had been breached.
Korn/Ferry said the affected databases are not designed to collect credit card, bank account, social security numbers, government identification numbers or health information.
The company said it was working closely with law enforcement on the breach but had no knowledge of any misuse of any information that may have been compromised.
Korn/Ferry shares were little changed at $14.09 in early trading on the New York Stock Exchange.
(Reporting by Bijoy Koyitty in Bangalore; Editing by Saumyadeb Chakrabarty)