According to CISA, FBI, NSA, Polish Military Counterintelligence, CERT Polska, and UK’s National Cyber Security Centre, Russian actors known by names including APT 29 are and have been exploiting servers hosting JetBrains TeamCity software since at least September, 2023. This software is used for software compilations, including building, testing and releasing software. The potential impact is pretty large, including supply chain operations (think Solarwinds). The article details IOCs
https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-347a