Description

A threat actor known as Cavalry Werewolf, with overlaps in sharing with the hacking group YoroTrooper, has been seen attacking the Russian public sector using malware families like FoalShell and StallionRAT. BI.ZONE is tracking this cluster, which also demonstrates overlaps with SturgeonPhisher, Silent Lynx, Comrade Saiga, ShadowSilk, and Tomiris. The attacks, monitored between May and August 2025, employed spear-phishing emails that portrayed themselves as messages from Kyrgyz government officials, mainly targeting Russian state institutions and businesses operating in energy, mining, and manufacturing industries. The attackers used forged and sometimes hijacked email addresses, including one attributed to the regulatory body of the Kyrgyz Republic, to deliver malicious RAR files. These repositories provided FoalShell, which is an ultralightweight reverse shell used in Go, C++, and C#, and StallionRAT, a multi-language, Go-written, PowerShell-written, and Python-written RAT. StallionRAT has features for executing commands, uploading files, and exfiltrating data through a Telegram bot using commands such as `/list`, `/go`, and `/upload`. ReverseSocks5Agent and ReverseSocks5, among other tools, were also delivered, as well as commands to collect device information. Cavalry Werewolf's affiliation with Tomiris earlier associated with a Kazakhstan-resident actor (Storm-0473) by Microsoft indicates regional connections. Usage of English and Arabic filenames indicates a wider targeting horizon than Russia. BI.ZONE states that the group is dynamically enriching its toolkit, highlighting the importance of real-time intelligence for proper detection and response measures. The report also identifies a wider cyber threat landscape, with at least 500 Russian companies in the field of commerce, finance, education, and entertainment that have been breached. In 86% of instances, attackers launched attacks against public-facing web applications, used gs-netcat for persistence, and employed tools such as Adminer and mysqldump to steal data.