Backdoors are common, but rarely malicious Backdoors are a
common problem in software. About 20% of home routers have a
backdoor in them, and 50% of industrial control computers have a
backdoor. The cause of these backdoors isn't malicious, but a
byproduct of software complexity. Systems need to be debugged
before being shipped to customers. Therefore, the software
contains debuggers. Often, programmers forget to disable the
debugger backdoors before shipping. This problem is notoriously
bad for all embedded operating systems (VxWorks, QNX, WinCE,
etc.). Chips have reached the software level of complexity. It
is rare that any designer builds a chip from scratch. Instead,
designers construct a chip from building-blocks. One of the most
common building-blocks is the debugger, known as JTAG. This is a
standard way of soldering some wires to the chip and connecting
to the USB port, allowing common tools to debug your custom
chip. Whereas companies (should) disable the debug feature in
the version they send to cus