The Russia-linked threat actor known as Turla has been observed using a new backdoor called TinyTurla-NG as part of a three-month-long campaign targeting Polish non-governmental organizations in December 2023.
"TinyTurla-NG, just like TinyTurla, is a small 'last chance' backdoor that is left behind to be used when all other unauthorized access/backdoor mechanisms have failed or been detected on the infected systems," Cisco Talos said in a technical report published today.
TinyTurla-NG is so named for exhibiting similarities with TinyTurla, another implant used by the adversarial collective in intrusions aimed at the U.S., Germany, and Afghanistan since at least 2020. TinyTurla was first documented by the cybersecurity company in September 2021.
Turla, also known by the names Iron Hunter, Pensive Ursa, Secret Blizzard (formerly Krypton), Snake, Uroburos, and Venomous Bear, is a Russian state-affiliated threat actor linked to the Federal Security Service (FSB).
In recent months, the threat actor has singled out the defense sector in Ukraine and Eastern Europe with a novel .NET-based backdoor called DeliveryCheck, while also upgrading its staple second-stage implant referred to as Kazuar, which it has put to use as early as 2017.
The latest campaign involving TinyTurla-NG dates back to December 18, 2023, and is said to have been ongoing up until January 27, 2024. However, it's suspected that the activity may have actually commenced in November 2023 based on the malware compilation dates.
It's currently not known how the backdoor is distributed to victim environments, but it has been found to employ compromised WordPress-based websites as command-and-control (C2) endpoints to fetch and execute instructions, enabling it to run commands via PowerShell or Command Prompt (cmd.exe) as well as download/upload files.
TinyTurla-NG also acts as a conduit to deliver PowerShell scripts dubbed TurlaPower-NG that are designed to exfiltrate key material used to secure the password databases of popular password management software in the form of a ZIP archive.
"This campaign appears to be highly targeted and focused on a small number of organizations, of which until now we can only confirm Poland based ones," a Cisco Talos researcher told The Hacker News, noting that the assessment is based on the current visibility.
"This campaign is highly compartmentalized, a few compromised websites acting as C2s contact a few samples, meaning that it's not easy to pivot from one sample/C2 to others using the same infrastructure that would give us confidence they are related."
The disclosure comes as Microsoft and OpenAI revealed that nation-state actors from Russia are exploring generative artificial intelligence (AI) tools, including large language models (LLMs) like ChatGPT, to understand satellite communication protocols, radar imaging technologies, and seek support with scripting tasks.
Additional Details About TinyTurla-NG Emerge
Cisco Talos, in a follow-up report published on February 22, 2023, said it has observed the TinyTurla-NG backdoor being used to deliver a modified version of the Chisel tunneling software alongside credential harvesting scripts and tools for elevated process execution.
"The adversaries use TinyTurla-NG to perform additional reconnaissance to enumerate files of interest on the infected endpoints and then exfiltrate these files [using TurlaPower-NG]," the company said.
