the-web-application-hackers-handbook

Chapter 3 n Web Application Technologies 57
Web services use Simple Object Access Protocol (SOAP) to exchange data.
SOAP typically uses the HTTP protocol to transmit messages and represents
data using the XML format.
A typical SOAP request is as follows:
POST /doTransfer.asp HTTP/1.0
Host: mdsec-mgr.int.mdsec.net
Content-Type: application/soap+xml; charset=utf-8
Content-Length: 891
18281008
1430
False
08447656
In the context of web applications accessed using a browser, you are most
likely to encounter SOAP being used by the server-side application to communicate
with various back-end systems. If user-supplied data is incorporated
directly into back-end SOAP messages, similar vulnerabilities can arise as for
SQL. These issues are described in detail in Chapter 10.
If a web application also exposes web services directly, these are also worthy
of examination. Even if the front-end application is simply written on top of the
web service, differences may exist in input handling and in the functionality
exposed by the services themselves. The server normally publishes the available
services and parameters using the Web Services Description Language (WSDL)
format. Tools such as soapUI can be used to create sample requests based on a
published WSDL file to call the authentication web service, gain an authentication
token, and make any subsequent web service requests.
Client-Side Functionality
For the server-side application to receive user input and actions and present
the results to the user, it needs to provide a client-side user interface. Because
all web applications are accessed via a web browser, these interfaces all share a