Win32 Detour of WinINet InternetOpen

If you use Microsoft Internet Explorer with an intercepting proxy like burp proxy, you need to set your system-wide proxy to point to the relevant local port. This can be a hassle, and also results in all WinINet traffic being redirected through the local proxy.

The program below allows specific proxy settings to be configured per application instance, so that you can launch an individual instance of Internet Explorer which uses a local proxy, and have all other programs use the default system-wide proxy setting. It also allows you to launch other applications like thick web clients using a local proxy, provided they use WinINet internally for their web access.

The program uses Microsoft's Detours framework for instrumenting Win32 functions. When a WinINet application first accesses the Internet, it calls InternetOpen to initialise data structures and specify some configuration, including any proxy to be used. The Detour hooks this call, and replaces the proxy configuration with "127.0.0.1:8080". It can also be used to set an arbitrary User-Agent string and specify domains which won't use the proxy.

To use the Detour, download withdll.exe and wininetdetour.dll, and use the following command to launch Internet Explorer:

withdll.exe /d:c:\path\to\wininetdetour.dll "c:\Program Files\Internet Explorer\iexplore.exe"

source code: wininetdetour.cpp

compiled dll: wininetdetour.dll

Microsoft Detours program to launch a target application and inject a dll: withdll.exe

Please view and accept Microsoft's terms and conditions for using Detours before using this program.

IBurpExtender interface for extending Burp Suite

Download the IBurpExtender documentation.