Palo Alto Networks discovered a custom RAT dubbed UBoatRAT that has been used in targeted attacks on personnel or organizations related to South Korea.

Security experts from Palo Alto Networks discovered custom remote access Trojan (RAT) dubbed UBoatRAT that has been used in targeted attacks on personnel or organizations related to South Korea and the video gaming industry.

The UBoatRAT has been distributed through Google Drive links, the malware obtains the address of the command and control (C&C) server from GitHub and uses Microsoft Windows Background Intelligent Transfer Service (BITS) to maintain persistence.

The address of the C&C and the destination port are hidden in a file hosted on GitHub, and the malware accesses the file using a specific URL. UBoatRAT communicates with the C&C served using a custom protocol.

Attackers used the GitHub account ‘elsa999’, according to the researchers the author has been frequently updating repositories since July.

UBoatRAT was first spotted on May 2017, at the time it was a simple HTTP backdoor leveraging a public blog service in Hong Kong and a compromised web server in Japan for C&C.

Across the months the authors added several new features to the RAT, the last variant was released during summer.

“Palo Alto Networks Unit 42 has identified attacks with a new custom Remote Access Trojan (RAT) called UBoatRAT.” reads the analysis published by Palo Alto Networks.

“The attacks with the latest variants we found in September have following characteristics.

Targets personnel or organizations related to South Korea or video games industry

Distributes malware through Google Drive

Obtains C2 address from GitHub

Uses Microsoft Windows Background Intelligent Transfer Service(BITS) to maintain persistence.”

The exact targets aren’t still clear at the moment, the experts speculate the hackers aimed to Korea or the video games industry, because Korean-language game titles, Korea-based game company names, and some words used in the video games business were used for delivery.

The UBoatRAT performs malicious activities on the infected machine only when joining an Active Directory Domain, this means that user systems that are not part of a domain would not be impacted.

Threat actors delivered the RAT through a ZIP archive hosted on Google Drive and containing a malicious executable file disguised as a folder or a Microsoft Excel spreadsheet. The latest variants of the UBoatRAT masquerade as Microsoft Word document files.

The RAT halts its execution when detects a virtualization software such as VMWare, VirtualBox, QEmu, when executed it attempts to obtain the Domain Name from network parameters. If it fails to get the domain name, it displays a fake error message and quits.

Otherwise, UBoatRAT copies itself as C:\programdata\svchost.exe, and creates and executes C:\programdata\init.bat, then it displays a specific message and quits.

Experts observed that the malware relies the Microsoft Windows Background Intelligent Transfer Service (BITS), a service for transferring files between machines, to maintain the persistence.

“Bitsadmin.exe is a command-line tool user can create and monitor BITS jobs. The tool provides the option, /SetNotifyCmdLine which executes a program when the job finishes transferring data or is in error. UBoatRAT takes advantage of the option to ensure it stays running on a system, even after a reboot.” continue the analysis.

Once established a covert channel with C&C, the malware waits following backdoor commands from the attacker.

Command Description alive Checks if whether the RAT is alive online Keeps the RAT online by sending the packets to C2 periodically upfile Uploads file to compromised machine downfile Downloads file from compromised machine exec Executes process with UAC Bypass using Eventvwr.exe and Registry Hijacking start Starts CMD shell curl Downloads file from specified URL pslist Lists running processes pskill Terminates specified process

The researchers have identified fourteen samples of UBoatRAT, as well as one downloader associated with the attacks.

“Though the latest version of UBoatRAT was released in September, we have seen multiple updates in elsa999 accounts on GitHub in October. The author seems to be vigorously developing or testing the threat.” concluded Palo Alto Networks.

Pierluigi Paganini

(Security Affairs – malware, UBoatRAT)

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