SMS Password Authorization Bypass via Failed Attempt Counter

The SMS control function of IE-SR-2TX-WL-4G devices can require a password for SMS commands via the 'Enable Password Authorization' setting. The device increments a retry counter on each failed SMS password attempt; after 5 consecutive failed attempts, SMS password authorization is automatically disabled. An unauthenticated remote attacker who is able to send SMS messages to the device can deliberately trigger this by submitting 5 or more invalid passwords, after which subsequent SMS commands are executed without requiring a password, resulting in potential limited configuration tampering, limited information leakage and potentially full loss of availability.