How Infostealer Logs Became the Fuel Behind Massive Cloud Data Breaches

Infostealer malware has quietly become the single most important initial-access commodity in the cybercrime economy, replacing traditional phishing and exploit-driven intrusions as the leading precursor to enterprise breaches and ransomware. Rather than breaking into networks, modern threat actors buy their way in by purchasing “stealer logs” containing valid usernames, passwords, session cookies, and SSO tokens harvested from infected endpoints, then replaying those sessions directly against cloud consoles, SaaS platforms, and VPN gateways. Cisco Talos’ Q1 2026 incident-response data confirms phishing and credential-based access have overtaken exploit-driven intrusions as the top initial-access vector, and the credentials in question are overwhelmingly stealer-log-derived. This report unpacks the full kill chain from infection to cloud compromise and provides a defender-ready reference of known infection vectors, malware tooling, targeted sectors, exploited weaknesses, and indicators of compromise (IOCs). The 2024 Snowflake breach remains the canonical case study of this pipeline in action. Threat actor UNC5537 (aka Scattered Spider/ShinyHunters) did not exploit a Snowflake vulnerability it used credentials harvested by infostealer malware from Snowflake customer employees, with some infections dating back to…