Second, the system itself is flawed. Some computer network systems did not take effective security measures when they were established, such as allowing interconnection with other networks at will, unprotected files, untimely backup, etc., which are easy for "people" to break into the system or users to modify or delete files easily, and are not easy to recover.
Third, the system permission level is set too little, and the user password is short. For convenience, some users' passwords and passwords are too simple to be changed for a long time, and there is no special management authority and user password in the system. Some passwords were leaked and not updated in time.
Fourth, the audit system is not strict. Some computer systems have not carried out necessary and rigorous tests on these software before adding new application software or upgrading existing software, and have not put into trial operation afterwards, so it is easy to bring unsafe factors into the system.