A new ransomware is being distributed by the Magnitude exploit kit: Magniber (detected by Trend Micro as RANSOM_MAGNIBER.A), which we found targeting South Korea via malvertisements on attacker-owned domains/sites. The development in Magnitude’s activity is notable not only because it eschewed Cerber—its usual ransomware payload—in favor of Magniber. Magnitude now also appears to have become an exploit kit expressly targeting South Korean end users.

The Magnitude exploit kit, which previously had a global reach, was offered as a service in the cybercriminal underground as early as 2013. It then left the market and became a private exploit kit that mainly distributed ransomware such as CryptoWall. At the start of the second half of 2016, Magnitude shifted focus to Asian countries, delivering various ransomware such as Locky and Cerber. More recently though, we noticed that Magnitude underwent a hiatus that began on September 23, 2017, and it then returned on October 15. With help from Kafeine and malc0de, we were able to uncover Magnitude’s new payload, Magniber.