Disclosed are exemplary aspects of systems and methods for blocking execution of scripts. An exemplary method comprises: intercepting a request for a script from a client to a server; generating a bytecode of the intercepted script; computing a hash sum of the generated bytecode; determining a degree of similarity between the hash sum of the bytecode and a plurality of hash sums of malicious and clean scripts stored in a database; identifying a similar hash sum from the database whose degree of similarity with the hash sum of the bytecode is within a threshold of similarity; determining a coefficient of trust of the similar hash sum; determining whether the requested script is malicious based on the degree of similarity and the coefficient of trust of the similar hash sum; and blocking the execution of the malicious script on the client.