Threat Actor Targets Gambling and Betting in Southeast Asia
Gambling and betting operations in Southeast Asia have been targeted in a campaign active since May 2019, Trend Micro reports.
Dubbed DRBControl, the adversary behind the attacks is using a broad range of tools for cyber-espionage purposes, including publicly available and custom utilities that allow it to elevate privileges, move laterally in the compromised environments, and exfiltrate data.
The intrusion begins with spear-phishing Microsoft Word files, with three different document versions identified: they embed an executable, a BAT file, and PowerShell code, respectively. Two very similar variations of the employed phishing content were observed.
The first two document versions execute the same payload onto the target system, and the third one is believed to be leading to the same piece of malware too.
DRBControl employed two previously unknown backdoors in this campaign, but also used known malware families, such as the PlugX RAT, the Trochilus RAT, and the HyperBro backdoor, along with various custom post-exploitation tools, Trend Micro explains in a detailed report (PDF).
Both of the backdoors use DLL side-loading through the Microsoft-signed MSMpEng.exe, with the malicious code then injected into the svchost.exe.
Written in C++, the first of the threat actor’s backdoors can bypass user account control (UAC), achieve persistence via a registry key, sends out information such as hostname, computer name, user privileges, Windows version, current time, and a campaign identifier.
A recent version of the malware was observed using Dropbox for command and control (C&C), with multiple repositories employed to store the infected machine’s information, store commands and post-exploitation tools, and store files exfiltrated from the machine.
The Dropbox-downloaded backdoor has keylogging functions and can receive commands to enumerate drives and files, execute files, move/copy/delete/rename files, upload to Dropbox, execute commands, and run binaries via process hollowing.
Also written in C++, the second backdoor too has UAC bypass and keylogging capabilities. The security researchers discovered an old version of this backdoor being delivered by a Word document from July 2017, suggesting that DRBControl has been active for a long time.
Post exploitation tools employed by the threat actor include a clipboard stealer, a network traffic tunnel EarthWorm, public IP address retriever, NBTScan tool for enumerating NetBIOS shares, brute-force tool, and an elevation of privilege tool for exploiting CVE-2017-0213. Multiple password dumpers, tools for bypassing UAC, and code loaders were also identified.
The use of the same domain in one of the backdoors, a PlugX sample, and Cobalt Strike allowed the researchers to link DRBControl to all three malware families. Additionally, the researchers identified connections with Winnti (via mutexes, domain names, and issued commands) and Emissary Panda (the HyperBro backdoor appears to be exclusive to Emissary Panda).
This cyber-espionage campaign was targeted at gambling and betting companies in Southeast Asia, with no attacks in other parts of the world being confirmed to date.
“The threat actor described here shows solid and quick development capabilities regarding the custom malware used, which appears to be exclusive to them. The campaign exhibits that once an attacker gains a foothold in the targeted entity, the use of public tools can be enough to elevate privileges, perform lateral movements in the network, and exfiltrate data,” Trend Micro concludes.