Transparent proxies allow organizations to influence and monitor the traffic from its users without their knowledge or participation. Transparent proxies act as intermediaries between a user and end destination, and aren't generally apparent to users sitting behind them. Enterprises, Hotels, and Internet Service Providers often use transparent proxy products to lower bandwidth consumption, speed up page loads for their users, and for monitoring and filtering of web surfing. When certain transparent proxy architectures are in use an attacker can achieve a partial Same Origin Policy Bypass resulting in access to any host reachable by the proxy via the use of client plug-in technologies (such as Flash, Applets, etc) with socket capabilities. This write up will describe this architecture, how it may be abused by Flash, its existence in various network layouts, and mitigations.
Based out of Silicon Valley, California, Robert currently works for a large multinational organization where he focuses on everything from SDLC program development to everything application security related. Robert is a co-founder of The Web Application Security Consortium (http://www.webappsec.org/), moderates The Web Security Mailing List (http://www.webappsec.org/lists/websecurity/), and runs the Threat Classification Project (http://www.webappsec.org/projects/threat). He has also contributed to many community efforts such as the Snort IDS, and the Open Web Application Security Project's (OWASP) Testing project.