If the employee are destroying property owned by the employer, for which is not part of the employee role or assignment, then they could be charged with hacking and property destruction just as if it was done by someone outside the company. The way around this that some people can attempt is work-to-rule strike. That would be a legal way to sabotage a contract without actually going beyond that of the employee contract.
>>belorn+(OP)
Again I was thinking of things like submitting non-functional application or data, not obvious property crimes like destruction of property.