Making defensive copies of mutable method parameters mitigates against a variety of security vulnerabilities; see OBJ06-J. Defensively copy mutable inputs and mutable internal components for additional information. However, inappropriate use of the clone method can allow an attacker to exploit vulnerabilities by providing arguments that pass initial validation but subsequently return unexpected values. Such objects may consequently bypass validation and security checks. Never use the clone() method of nonfinal classes to make defensive copies. So never use the clone method for defensive copying of untrusted method parametersWhen such a class is passed as an argument to a method, treat the argument as untrusted and do not use the clone() method provided by the class.
This guideline is a specific instance of OBJ58-JG. Do not rely on overridden methods provided by untrusted code.
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