Offensive operations have been promoted by the aggressors using computer as a tool or target, resulting, a cyber attack in web-applications of an organization or the infrastructure of entire nation. Depending upon the attacker's target, one can classify some of the mostly occurred cyber attacks into five broad categories. It reports some of the common methods adopted in conducting these attacks and their defending techniques. This paper mainly address the possibility of cyber attacks due to the execution of malicious or unintended nature of scripts. It formulates a verification method of web document and perform experiment in the client-side using its benign script structure. This method is capable of detecting any malicious script which inserts in the web-document during transportation from server to the client or due to the previously stored content in the client or server operation. Satisfactory results have been found with the own-generated and publicly available data-set.