Threat actors are leveraging known flaws in Sunlogin software to deploy the Sliver command-and-control (C2) framework for carrying out post-exploitation activities.
The findings come from AhnLab Security Emergency response Center (ASEC), which found that security vulnerabilities in Sunlogin, a remote desktop program developed in China, are being abused to deploy a wide range of payloads.
“Not only did threat actors use the Sliver backdoor, but they also used the BYOVD (Bring Your Own Vulnerable Driver) malware to incapacitate security products and install reverse shells,” the researchers said.
Attack chains commence with the exploitation of two remote code execution bugs in Sunlogin versions prior to v22.214.171.124 (CNVD-2022-03672 and CNVD-2022-10270), followed by delivering Sliver or other malware such as Gh0st RAT and XMRig crypto coin miner.
In one instance, the threat actor is said to have weaponized the Sunlogin flaws to install a PowerShell script that, in turn, employs the BYOVD technique to incapacitate security software installed in the system and drop a reverse shell using Powercat.
The BYOVD method abuses a legitimate but vulnerable Windows driver, mhyprot2.sys, that’s signed with a valid certificate to gain elevated permissions and terminate antivirus processes.
It’s worth noting here that the anti-cheat driver for the Genshin Impact video game was previously utilized as a precursor to ransomware deployment, as disclosed by Trend Micro.
“It is unconfirmed whether it was done by the same threat actor, but after a few hours, a log shows that a Sliver backdoor was installed on the same system through a Sunlogin RCE vulnerability exploitation,” the researchers said.
The findings come as threat actors are adopting Sliver, a Go-based legitimate penetration testing tool, as an alternative to Cobalt Strike and Metasploit.
“Sliver offers the required step-by-step features like account information theft, internal network movement, and overtaking the internal network of companies, just like Cobalt Strike,” the researchers concluded.