Seoul is investigating an email-based cyber attack in which the sender impersonated the South Korean Ministry of Unification (MOU), the ministry announced on Friday, while declining to confirm reports that Pyongyang is linked to the phishing email.

The unification ministry took the measures after identifying the problem on Thursday, spokesperson Baik Tae-hyun told a press briefing.

The infected email containing a file originally written by the unification ministry and was distributed by a hacker group to targets earlier in the week.

Baik said the attached file is “identical” to a three-page HWP file of analysis of a New Year’s Speech delivered by