The Web Proxy Auto-Discovery (WPAD) Protocol is a method used by clients to locate the URL of a configuration file using DHCP and/or DNS discovery methods. Once detection and download of the configuration file is complete, it can be executed to determine the proxy for a specified URL.
The WPAD protocol only outlines the mechanism for discovering the location of this file, but the most commonly deployed configuration file format is the proxy auto-config format originally designed by Netscape in 1996 for Netscape Navigator 2.0.[1]The WPAD protocol was drafted by a consortium of companies including Inktomi Corporation, Microsoft Corporation, RealNetworks, Inc., and Sun Microsystems, Inc. (now Oracle Corp.). WPAD is documented in an INTERNET-DRAFT which expired in December 1999.[2] However, WPAD is still supported by all major browsers.[3][4] WPAD was first included with Internet Explorer 5.0.
Microsoft Winhttp Web Proxy Auto Discovery Service
This is a system service that handles proxy determination tasks for clients using the WinHTTP/WinINET HTTP(S) network stacks. Because the service is long-running, performance penalties are amortized (e.g. a 3 second delay once per boot is much cheaper than a 3 second delay every time your browser starts), and the service can maintain caches across different processes.
Nevertheless, a WPAD protocol is used to enable clients to auto discover the proxy settings, so manual configuration is not needed. All that needs to be done on the clients themselves is enabling the auto-detection of proxy settings.
WPAD auto-discovery is often enabled in enterprise environments, which enables us to attack the DNS auto-discovery process. We can do that by setting up a proxy on our attacking machine and instruct all the clients to forward the requests through our proxy, which enables us to save all the requests in a .pcap file. We could also change the responses which are being returned to the user to present different content.
Description: The original winhttp.dll is an important part of Windows and rarely causes problems. The winhttp.dll file is located in the C:\Windows\System32 folder.Known file sizes on Windows 10/11/7 are 351,232 bytes (33% of all occurrences), 703,056 bytes, 636,928 bytes, 589,312 bytes or 626,176 bytes. The service can be started or stopped from Services in the Control Panel or by other programs.The program is not visible. The winhttp.dll file is a trustworthy file from Microsoft.Therefore the technical security rating is 5% dangerous; but you should also compare this rating with the user reviews.
We are thinking about setting winhttp proxy to localhost:9000. but we fear that it will be unreachable when no user is logged in. so defender services and intunes services will be unavailable without reaching the MS endpoints.
Hi all,Same query here.We have many applications which use winhttp context.Today we have PAC file for internal network with GRE/IPSeC tunnela and not using transparent proxy .Same for remote users with tunel 1.0 with local proxy.We have mainly issue faced related to hybrid domain join to azure and next think agent communication and also sccm app store communication.Today we perform URL bypass for these domains in PAC file and for azure ad hybrid domain we route via ghost Zen IP internal through our internal corporate vpn to go via Internal DC GRe tunnels to zscaler tunnels which is like tromboning.
Collector should work out of the box with transparent proxies as well. Transparent proxies automatically intercept network traffic that goes from the corporate network to the Internet, so that clients are not aware that their traffic is traversing a proxy.
Because the Collector runs as a Windows service, it can read the proxy settings specified both at the application level (its own custom configuration) and at the system level, but not at the user level. Therefore, the Collector supports the methods described below to configure its proxy settings.
The WinHTTP interface is meant to be used by server applications and system services such as the Collector. It provides proxy settings at the system level and its configuration is stored in the Windows Registry:
The Web Proxy Auto-Discovery (WPAD) protocol is a method to set the proxy settings automatically by leveraging the DHCP and DNS protocols. WPAD uses discovery methods in DHCP and DNS to find out the URL of a PAC file, in much the same way as WinINet gets its LAN settings when automatic detection is enabled.
Automatic proxy: Get a PAC file from the specified URL to automatically determine the proxy settings. A proxy-auto-config (PAC) file is a JavaScript file with a single function that determines which proxy should be used for each client connection. 2ff7e9595c
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