Permission escalation caused by improper permission setting of startup scripts on some Android phones of Huawei

Some Huawei mobile phones are improperly configured with/data/drm permissions, so that malicious apps can escalate their permissions through a few steps.
Drwxrwxr-x system sdcard_rw 2013-04-15 drm installs a malicious app (android is allowed. permission. WRITE_EXTERNAL_STORAGE ), after modifying the permission, encrypt-x drm system 2013-03-26 IDM drwx ------ drm system 2013-03-26 fwdlock unlock app_60 app_60 2013-04-15 rights->/sys/kernel-x system sdcard_rw 2013-03-26 widevine after the phone is restarted-rwxrwxr-x system sdcard_rw 4096 2013-04-15 05:01 uevent_help Then, the malicious app can write arbitrary malicious program paths to uevent_helper, and the kernel will run as root.