In a DefCamp Security Conference, held in Romania, the system administrator of a Dutch IT company, Bogdan Alecu, revealed that Google Nexus phones — including Nexus 5 — are at risk of of DDoS via Flash SMS messages.

He discovered that the Smartphone would automatically reboot itself, or lose network connection, when it receives bulk Class 0 “Flash” SMS messages, which remained unnoticed.

He observed that if the phone received as many as 30 Flash SMS messages, which were neither saved nor declined, the phone would reboot without notifying the user.

A major disadvantage for the Nexus users is the fact that the smartphone doesn’t give an audio notification to its owners when such a Flash message is received. Therefore, it’s up to the users to keep a constant check on their phones and immediately decline or save these Flash messages before their Nexus phone gets infected.


However, a company that designs and creates software solutions for mobile devices Silent Services has recently developed an app that will protect all the Nexus users from Flash SMS attacks. Receiving blessings from all the Nexus phone owners, Silent Services quotes Lao Tzu as its tag line “The quieter you become, the more you are able to hear”.

Class0Firewall is the new firewall app on Google Play that isn’t just being downloaded by almost all the Nexus phone users but also, the app is providing its safety services to other mobile phone users.

Designed specifically to guard the smartphones from SMS attacks discovered by Bogdan Alecu, the app provides for defense which was primarily an idea suggested and demonstrated at the DefCamp Security Conference.

The firewall app defends smartphones by limiting the number of Flash SMS which is received by the mobile device. A certain value needs to be set by the user for threshold and block duration.

In case if the incoming Flash messages exceed the predetermined number, the messages are dropped by the firewall. For each dropped message, a toast message makes its appearance.

Class0Firewall is truly an amazing app that is compatible with all devices. However, a notice in the description of the app reads, “Due to the SMS API change in Android 4.4 KitKat the Firewall has no effect and your device is still vulnerable. I will try to find a way around.”

Undoubtedly, on the Cyber Monday, Class0Firewall has come with a new hope for those who owns the Nexus smartphones. As for the rest of the smartphone owners, it’s time to stop worrying about being attacked by Flash SMS messages and move on with some real work on hands.


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