Topinambour

Topinambour is a Trojan dropper that installs other threats onto your PC with few or no symptoms visible. Its attacks are related closely to campaigns run by the Turla APT, a threat actor that specializes in data exfiltration for targets of traditional interest to the Russian government. Windows users should keep anti-malware products on hand for removing Topinambour or identifying it.

Just a Drop of Trouble in Your Software

Like any well-funded and resourceful threat actor, the Turla APT is a group of hackers that changes strategies and software to suit the current climate. 2019 is showing them active with a host of backdoor Trojans and Trojan downloaders, such as the PowerShell-based PowerStallion or the originally JavaScript-using KopiLuwak, all of which appear with the help of other threats. The delivery mechanism for them, frequently, is Topinambour.

Topinambour – named for the sunchoke or Jerusalem artichoke – is a Trojan dropper that runs off of Microsoft's .NET Framework for Windows. Victims are downloading it unintentionally after exposing their PCs to compromised versions of virtual private network utilities, censorship-bypassing tools like Psiphon, and Microsoft Office cracks. Although malware experts have no information on how these downloads are maintaining their distribution, it's not beyond the Turla APT's resources to build dedicated misleading websites, along with seeding torrents or delivering malvertising content.

These installers, besides providing the promised programs, also, place Topinambour on the computer, which waits for shell commands from its C&C. Further attacks, including the installation of so-called 'fileless' Trojans on the system, occur through a series of instructions like Windows's 'copy.' These later stages of infection include more powerful Trojans than Topinambour, which can download and execute arbitrary files, conduct invasive system changes, and provide remote administration options for the attackers.

Staying on Top of Trojan-Spy Development

Entities more likely than others of being targets of the Turla APT's campaigns include governments, media companies, and NGOs in ex-Soviet states and the US. Current infection vectors for Topinambour imply that the criminals are attempting breaches of the network security of political dissidents, due to the emphasis on VPN and anti-censorship application. Besides the always-relevant caution around illicit software cracks, malware experts recommend double-checking the safety of any installers for Softether VPN and Psiphon3.

Many of the threats that Topinambour can install will not leave behind visible files on the user's drives, due to persisting via Registry exploits and other mechanisms. Besides that, all Trojans associated with the second and third-stages of infections emphasize stealth-related features for gaining long-term persistence and collecting information virtually. Users can, however, protect their systems with anti-malware products that, hopefully, will stop and remove Topinambour before any harm occurs.

Topinambour is a small package with big surprises for anyone who underestimates the capabilities of Windows shell commands combined with JavaScript, scheduled tasks, and compromised blogs serving as Command & Control domains. The best hopes of outwitting it – like all attacks from the Turla APT – always involves preventing infections by maintaining safe downloading behavior.