Comment 0 for bug 2047699

see https://github.com/openstack/tripleo-heat-templates/blob/1393d39be367db3acb02508e0e858395a4e4fefa/scripts/undercloud-upgrade-ephemeral-heat.py#L89

 we frist write a file, then chmod the mode of the file as 644.

  with open(db_path, 'w') as out:
        subprocess.run([
            'sudo', 'podman', 'exec', '-u', 'root',
            'mysql', 'mysqldump', 'heat'], stdout=out,
            check=True)
    os.chmod(db_path, 0o600)

When a file is first created and then its permissions are later changed using chmod, there exists a potential security risk known as a time-of-check to time-of-use (TOCTOU) attack. In this type of attack, an attacker exploits the time window between when the file is initially written and when its permissions are modified.

During this time window, the attacker may gain access to the file and manipulate its contents or execute malicious code, especially if the file is located in a directory that is writable by the attacker. By the time the permissions are changed using chmod, the attacker may have already exploited the file for their malicious purposes.

This type of attack is a result of the temporal gap between the creation of the file and the subsequent permission modification, allowing for potential unauthorized access and manipulation. This highlights the importance of properly securing sensitive files from the moment of creation and throughout their lifecycle to mitigate the risk of such attacks.