#+SETUPFILE: ../../../template/level-2.org
#+TITLE: Signal DoS
#+DATE: <2018-05-30 Wed 00:00>
#+AUTHOR: vaeringjar
#+EMAIL: vaeringjar@land
#+DESCRIPTION: Under some conditions, Signal can silently discontinue sending messages.
#+KEYWORDS: security


* Post

It seems that as of the time of this writing, for Signal users set to
use Signal as default for all SMS/MMS, a person A using Signal can
block themselves from others using Signal if they, person A,
discontinues using Signal. The process for removing them seems tedious
and unreliable in my tests. The issue link below seems to understand
part of the problem.

I also suggest that, in an extreme case, a person C non-user of Signal
could find themselves in a particular pickle if person D used SS7 to
hijack their tele-traffic. Easiest problem to reproduce, Person D
could then add Signal, message all other recent contacts, and then
remove C's temporary Signal account. After this, any contacts of
person C would continue to send Signal-based messages to C instead of
reverting to standard SMS/MMS.

Including the base, I tried these two:

- https://github.com/signalapp/Signal-Android/issues/4678
- https://github.com/signalapp/Signal-Android/issues/4678#issuecomment-265078478
- https://github.com/signalapp/Signal-Android/issues/4678#issuecomment-376108289
