Telecommunications and manufacturing sectors in Central and South Asian international locations have emerged because the goal of an ongoing marketing campaign distributing a brand new variant of a recognized malware referred to as PlugX (aka Korplug or SOGU).
“The brand new variant’s options overlap with each the RainyDay and Turian backdoors, together with abuse of the identical professional functions for DLL side-loading, the XOR-RC4-RtlDecompressBuffer algorithm used to encrypt/decrypt payloads and the RC4 keys used,” Cisco Talos researchers Joey Chen and Takahiro Takeda mentioned in an evaluation revealed this week.
The cybersecurity firm famous that the configuration related to the PlugX variant diverges considerably from the standard PlugX configuration format, as an alternative adopting the identical construction utilized in RainyDay, a backdoor related to a China-linked risk actor often called Lotus Panda (aka Naikon APT). It is also probably tracked by Kaspersky as FoundCore and attributed to a Chinese language-speaking risk group it calls Cycldek.
PlugX is a modular distant entry trojan (RAT) extensively utilized by many China-aligned hacking teams, however most prominently by Mustang Panda (aka BASIN, Bronze President, Camaro Dragon, Earth Preta, HoneyMyte, RedDelta, Purple Lich, Stately Taurus, TEMP.Hex, and Twill Hurricane).
Turian (aka Quarian or Whitebird), then again, is assessed to be a backdoor solely employed in cyber assaults focusing on the Center East by one other superior persistent risk (APT) group with ties to China known as BackdoorDiplomacy (aka CloudComputating or Faking Dragon).
The victimology patterns – significantly the deal with telecommunications firms – and technical malware implementation had yielded proof suggesting probably connections between Lotus Panda and BackdoorDiplomacy, elevating the chance that both the 2 clusters are one and the identical, or that they’re acquiring their instruments from a standard vendor.
In a single incident detected by the corporate, Naikon is claimed to have focused a telecom agency in Kazakhstan, a rustic that shares its borders with Uzbekistan, which has been beforehand singled out by BackdoorDiplomacy. What’s extra, each hacking crews have been discovered to zero in on South Asian international locations.
The assault chains primarily contain abusing a professional executable related to Cellular Popup Utility to sideload a malicious DLL that is then used to decrypt and launch PlugX, RainyDay, and Turian payloads in reminiscence. Current assault waves orchestrated by the risk actor have closely leaned on PlugX, which makes use of the identical configuration construction as RainyDay and contains an embedded keylogger plugin.
“Whereas we can not conclude that there’s a clear connection between Naikon and BackdoorDiplomacy, there are important overlapping elements – comparable to the selection of targets, encryption/decryption payload strategies, encryption key reuse and use of instruments supported by the identical vendor,” Talos mentioned. “These similarities recommend a medium confidence hyperlink to a Chinese language-speaking actor on this marketing campaign.”
Mustang Panda’s Bookworm Malware Detailed
The disclosure comes as Palo Alto Networks Unit 42 sheds mild on the internal workings of the Bookworm malware utilized by the Mustang Panda actor since 2015 to achieve in depth management over compromised techniques. The superior RAT comes fitted with capabilities to execute arbitrary instructions, add/obtain recordsdata, exfiltrate information, and set up persistent entry.
Earlier this March, the cybersecurity vendor mentioned it recognized assaults focusing on international locations affiliated with the Affiliation of Southeast Asian Nations (ASEAN) to distribute the malware.
Bookworm makes use of legitimate-looking domains or compromised infrastructure for C2 functions in order to mix in with regular community site visitors. Choose variants of the malware have additionally been discovered to share overlaps with TONESHELL, a recognized backdoor related to Mustang Pana since late 2022.
Like PlugX and TONESHELL, assault chains distributing Bookworm depend on DLL side-loading for payload execution, though newer variants have embraced a method that includes packaging shellcode as universally distinctive identifier (UUID) strings, that are then decoded and executed.
“Bookworm is understood for its distinctive modular structure, permitting its core performance to be expanded by loading further modules straight from its command-and-control (C2) server,” Unit 42 researcher Kyle Wilhoit mentioned. “This modularity makes static evaluation more difficult, because the Chief module depends on different DLLs to offer particular performance.”
“This deployment and adaptation of Bookworm, operating in parallel with different Stately Taurus operations, showcases its long-term function within the actor’s arsenal. It additionally factors to a sustained, long-term dedication to its growth and use by the group.”
