چکیده (انگلیسی):

The world has shrunk in this internet era. The applications in the internet use XML and Web Services which
are simple, but powerful standards that enable applications to more efficiently communicate with each
other. Unfortunately this advantage is coupled with concerns of Web services security. All the services
provided by the internet face security problem. The hackers find a loophole to attack the web service to
eliminate the availability of service. One of the most severe threats is Denial of Service attacks which are
intended to annihilate the availability of a service. In this study we propose a schema to detect a special type
of Denial of Service attack where the hacker modifies the SOAP messages by expanding it. The message
expanded thus, takes a huge amount of memory while parsing and thereby denies service to a legitimate
request. To overcome this problem, in this study, we propose a new security scheme which adds a digital
signature to the message and also limits the upper bound of the length of the SOAP message.