(Sharing this from <https://www.fsf.org/blogs/community/replicant-developers-find-and-close-samsung-galaxy-backdoor>.)
# Replicant developers find and close Samsung Galaxy backdoor *This is a guest post by [Replicant](http://replicant.us) developer Paul Kocialkowski. The Free Software Foundation supports Replicant through its Working Together for Free Software fund. [Your donations](https://crm.fsf.org/civicrm/contribute/transact?reset=1&id=19) to Replicant support this important work.* Today's phones come with two separate processors: one is a general-purpose applications processor that runs e.g. Android; the other, known as the modem, baseband or radio, is in charge of communications with the mobile telephony network. This processor always runs a proprietary operating system, and these systems are known to have back-doors that make it possible to remotely convert the modem into a remote spying device. The spying can be operated using the device's microphone, but it could also use the precise GPS location of the device and access the camera, as well as the user data stored on the phone. Moreover, modems are connected most of the time to the operator's network, making the back-doors nearly always accessible. It is possible to build a device that isolates the modem from the rest of the phone, so it can't mess with the main processor or access other components such as the camera or the GPS. Very few devices offer such guarantees. In most devices, for all we know, the modem may have total control over the applications processor and the system, but that's nothing new. While working on [Replicant](http://replicant.us), a fully free/libre version of Android, we discovered that the proprietary program running on the applications processor in charge of handling the communication protocol with the modem actually implements a back-door that lets the modem perform remote file I/O operations on the file system. This program is shipped with the Samsung Galaxy devices and makes it possible for the modem to read, write and delete files on the phone's storage. On several phone models, this program runs with sufficient rights to access and modify the user's personal data. A technical description of the issue, as well as the list of known affected devices is available at the Replicant wiki: <http://redmine.replicant.us/projects/replicant/wiki/SamsungGalaxyBackdoor>. Provided that the modem runs proprietary software and can be remotely controlled, that back-door provides remote access to the phone's data, even in the case where the modem is isolated and cannot access the storage directly. This is yet another example of what unacceptable behavior proprietary software permits! Our free replacement for that non-free program does not implement this back-door. If the modem asks to read or write files, Replicant does not cooperate with it. Replicant does not cooperate with back-doors, but if the modem can take control of the main processor and rewrite the software in the latter, there is no way for a main processor system such as Replicant to stop it. But at least we know we have closed one back-door. -- John Sullivan | Executive Director, Free Software Foundation GPG Key: 61A0963B | http://status.fsf.org/johns | http://fsf.org/blogs/RSS Do you use free software? Donate to join the FSF and support freedom at <http://www.fsf.org/register_form?referrer=8096>. -- Liberationtech is public & archives are searchable on Google. Violations of list guidelines will get you moderated: https://mailman.stanford.edu/mailman/listinfo/liberationtech. Unsubscribe, change to digest, or change password by emailing moderator at [email protected].
