ROKRAT is a remote access trojan (RAT) that leverages a malicious Hangual Word Processor (HWP) document sent in spearphishing emails to infect hosts. The HWP document contains an embedded Encapsulated PostScript (EPS) object. The object exploits an EPS buffer overflow vulnerability and downloads a binary disguised as a .JPG file. The file is then decoded and the ROKRAT executable is initiated. The trojan uses legitimate Twitter, Yandex, and Mediafire websites for its command and control communications and exfiltration platforms, making them difficult to block globally. Additionally, the platforms use HTTPS connections, making it more difficult to gather additional data on its activities. Cisco's Talos Group identified two email campaigns. In one, attackers send potential victims emails from an email server of a private university in Seoul, South Korea with a sender email address of "email@example.com," the contact email for the Korea Global Forum, adding a sense of legitimacy to the email. It is likely that the email address was compromised and used by the attackers in this campaign. The second is less sophisticated and sends emails claiming to be from a free Korean mail service with a the subject line, "Request Help" and attached malicious HWP filename, "I'm a munchon person in Gangwon-do, North Korea." The ROKRAT developer uses several techniques to hinder analysis, including identifying tools usually used by malware analysts or within sandbox environments. Once it has infected a device, this trojan can execute commands, move a file, remove a file, kill a process, download and execute a file, upload documents, capture screenshots, and log keystrokes. Researchers believe the developer is a native Korean speaker and the campaign is currently targeting Korean-speakers.
- November 2017: A new version of ROKRAT was discovered. It shares code with Freenki, a downloader used in the FreeMilk campaign. A malicious document titled "Citizens' Alliance for North Korean Human Rights and Reunification of Korean Peninsula" drops and executes the trojan. (Cisco Talos)
- Cisco's Talos Group provides technical analysis of ROKRAT, available here.