CVE-2019-3984

Step 1: Target Identification: The attacker identifies a vulnerable Blink XT2 Sync Module (firmware prior to 2.13.11). Step 2: Payload Delivery: The attacker crafts a malicious firmware update script containing arbitrary commands. This script is hosted on a server controlled by the attacker. Step 3: Update Trigger: The attacker either waits for the device to automatically check for updates or attempts to manually trigger an update check (if possible). Step 4: Script Download: The vulnerable Sync Module downloads the malicious update script from the attacker's server. Step 5: Command Execution: The Sync Module executes the downloaded script, which contains the attacker's injected commands. These commands are executed with elevated privileges. Step 6: System Compromise: The attacker gains remote control of the Sync Module, potentially gaining access to the local network and video footage.

The vulnerability stems from a lack of proper input validation and sanitization within the Blink XT2 Sync Module's firmware update process. Specifically, the device downloads update scripts from the internet without adequately verifying the integrity or content of these scripts. Attackers can craft malicious scripts containing arbitrary commands and inject them into the update process. When the device executes the compromised script, these commands are executed with the privileges of the system, granting the attacker remote control. The root cause is likely a failure to implement secure coding practices, such as input validation and output encoding, when handling external data sources. This allows for command injection attacks.