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Articles by Josh Fleischer
Computer Science > Software Engineering
Teams deploying large language models in business contexts need evaluation systems, yet most treat evaluation as static model selection: run benchmarks, rank models, deploy the winner. This framing misses evaluation's primary value for production systems--diagnosing why a system underperforms and guiding what to fix. We present EvalLoop, a methodology for evaluation-driven iterative improvement.
ViewState Deserialization Zero-Day Vulnerability in Sitecore Products (CVE-2025-53690)
Written by: Rommel Joven, Josh Fleischer, Joseph Sciuto, Andi Slok, Choon Kiat Ng In a recent investigation, Mandiant Threat Defense discovered an active ViewState deserialization attack affecting Sitecore deployments leveraging sample machine keys that had been exposed in Sitecore deployment guides from 2017 and earlier. An attacker leveraged the exposed ASP.NET machine keys to perform remote code execution. Mandiant worked directly with Sitecore to address this issue.
Zero-Day Exploits in SonicWall Email Security Lead to Enterprise Compromise
Threat Research Blog April 20, 2021 | by Josh Fleischer, Chris DiGiamo, Alex Pennino In March 2021, Mandiant Managed Defense identified three zero-day vulnerabilities in SonicWall’s Email Security (ES) product that were being exploited in the wild. These vulnerabilities were executed in conjunction to obtain administrative access and code execution on a SonicWall ES device.
Obscured by Clouds: Insights into Office 365 Attacks and How Mandiant Managed Defense Investigates
Threat Research July 30, 2020 | by Joseph Hladik, Josh Fleischer With Business Email Compromises (BECs) showing no signs of slowing down, it is becoming increasingly important for security analysts to understand Office 365 (O365) breaches and how to properly investigate them. This blog post is for those who have yet to dip their toes into the waters of an O365 BEC, providing a crash course on Microsoft’s cloud productivity suite and its assortment of logs and data sources useful to investigators.
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