Police found that a North Korean hacking group was behind a data leak incident at Seoul National University Hospital in 2021, which led to the personal information of some 830-thousand patients and staff members to be leaked.

The National Police Agency confirmed Wednesday that North Korean hackers used seven domestic and overseas computer servers to infiltrate the hospital's intranet. 

Officials compared the incident with previous hacks known to be perpetrated by North Korea and found the same IP address was used in the attack's place of origin.

They also found North Korean vocabulary used in passwords as the hackers set up an account in the hospital's internal system.

Police say the hackers used the vulnerability of the hospital's online bulletin board where files containing malicious code could be uploaded.

Expecting similar attempts to continue, one police official asked businesses to keep up with security updates and store important computer data in encrypted form.  

Confirming the data leak in July 2021, Seoul National University Hospital reported the case to authorities including the police and the health ministry.