What is the ruling on receiving additional money in government work, disbursed under the name of "overtime" even though it is not performed, and is using government work resources for personal purposes considered permissible or forbidden?

An employee is not permitted to receive pay for hours not worked, unless the work system allows it and the officials are authorized by the ruler.

As for using work tools for purposes other than work-related interests, it is not permissible, unless explicit or customary permission is granted.