Infostealers exfiltrate credentials, session cookies, and sensitive data from
infected systems. With over 29 million stealer logs reported in 2024, manual
analysis and mitigation at scale are virtually unfeasible/unpractical. While
most research focuses on proactive malware detection, a significant gap remains
in leveraging reactive analysis of stealer logs and their associated artifacts.
Specifically, infection artifacts such as screenshots, image captured at the
point of compromise, are largely overlooked by the current literature. This
paper introduces a novel approach leveraging Large Language Models (LLMs), more
specifically gpt-4o-mini, to analyze infection screenshots to extract potential
Indicators of Compromise (IoCs), map infection vectors, and track campaigns.
Focusing on the Aurora infostealer, we demonstrate how LLMs can process
screenshots to identify infection vectors, such as malicious URLs, installer
files, and exploited software themes. Our method extracted 337 actionable URLs
and 246 relevant files from 1000 screenshots, revealing key malware
distribution methods and social engineering tactics. By correlating extracted
filenames, URLs, and infection themes, we identified three distinct malware
campaigns, demonstrating the potential of LLM-driven analysis for uncovering
infection workflows and enhancing threat intelligence. By shifting malware
analysis from traditional log-based detection methods to a reactive,
artifact-driven approach that leverages infection screenshots, this research
presents a scalable method for identifying infection vectors and enabling early
intervention.