An independent probe has found that KT was remiss in alerting authorities that its server was infected last year by stealthy malware, BPFDoor.

A joint public-private team investigating the KT hacking incident delivered the assessment when it announced its interim findings Thursday. 

BPFDoor is a stealthy backdoor, or a method of bypassing authentication to gain unauthorized access, that exploits the Berkeley Packet Filter mechanism in the Linux and Solaris operating systems.

This same malware was behind serious hacking attacks at SK Telecom earlier this year. 

Investigators found via server forensic analysis that KT discovered that 43 of its servers were infected with BPFDoor between March and July of last year but did not report its findings to authorities and instead took internal steps. 

The team said it regards KT’s move as a serious matter and will ask concerned agencies to take measures against KT.