Rule Definition
The attacks and consequences of improperly exporting a component may depend on the exported component: If access to an exported Service is not restricted, any application may start and bind to the Service. Depending on the exposed functionality, this may allow a malicious application to perform unauthorized actions, gain access to sensitive information, or corrupt the internal state of the application.

Remediation
A permission is required for securing Services

Violation Code Sample

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
 package="com.example.testapps.test1"> 
 ... 
    <service android:name=".MailListenerService" 
              android:enabled="true" 
              android:exported="true"> 
              <intent-filter></intent-filter> 
    </service> 
  ... 
</manifest>

Fixed Code Sample

1- Define permission in the top of the manifest file as following one 

<permission android:name="com.example.testapps.permission.BIND_TO_MAIL_LISTENER" android:protectionLevel="signature" /> 


2- Add the android:permission into service 

<manifest xmlns:android="http://schemas.android.com/apk/res/android" 
 package="com.example.testapps.test1"> 
 ... 
    <service android:name=".MailListenerService" 
              android:permission= 
                 "com.example.testapps.permission.BIND_TO_MAIL_LISTENER" 
              android:enabled="true" 
              android:exported="true"> 
              <intent-filter></intent-filter> 
    </service> 
  ... 
</manifest>

https://developer.android.com/topic/security/best-practices https://developer.android.com/guide/topics/manifest/receiver-element.html#prmsn https://cwe.mitre.org/data/definitions/926.html