The US Postal Service (USPS) has been the victim of a cyber-intrusion in which hackers managed to steal staff and customer data.
The source of the attacks is believed to be China, which is often accused of launching assaults on US utilities, industries and the government.
USPS said in a document entitled USPS Cyber Intrusion and Employee Data Compromise (PDF) that the attack was limited and that the authorities have been informed. It has also advised employees and consumers about the potential risks.
The hackers have taken a range of information, USPS said in a statement, and the company's workers may have taken the brunt of the losses.
"The intrusion is limited in scope and all operations of the Postal Service are functioning normally," USPS said.
"Information potentially compromised in the incident may include personally identifiable information about employees, including names, dates of birth, Social Security numbers, addresses, beginning and end dates of employment, emergency contact information and other information."
Customers who called USPS phone lines during the summer are expected to be affected, but will not need to take any action following the breach, according to the company.
The compromised customer data includes "names, addresses, telephone numbers, email addresses and other information".
Similar breaches have hit Home Depot and Target in recent months. According to reports the USPS losses were small in comparison, and affect 750,000 former and current employees and 2.9 million customers.
"The recent breach at USPS reinforces that data is the new currency and attackers are going after rich veins of private information, whether it's employee or customer data," said Eric Chiu, president and co-founder of cloud security firm HyTrust.
"In many ways, employee data is even more valuable because companies store very sensitive information like Social Security, contact, healthcare and financial data on employees which can be used to hijack a person's financial identity."
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