Re: Trojan Source Attacks

["Perry E. Metzger" <perry () piermont com>]

On 11/1/21 16:51, Jan Engelhardt wrote:
> > We have identified an issue affecting all compilers and interpreters that support Unicode.
> > [...]
> > The attached paper describes an attack paradigm -- which we believe to be novel -- discovered by security researchers 
> > at the
> > University of Cambridge.
> Not so novel. At one time, this picture made the rounds
> (https://twitter.com/acronis/status/1019152990022787072 - the pic is likely
> older than this 2018 tweet), and anyone who knew that Unicode had zero-width
> characters already made the connection.

If it was known to everyone, then why are so many language interpreters 
and compilers impacted? Surely if this was truly something that was well 
understood by the community, then it wouldn't be a problem. (Claims that 
people who write compilers are fools will be cheerfully ignored.)

There's a phenomenon in many social groupings of there being "folklore" 
that people don't seem to find worth writing down because "everyone" 
knows it, except then it turns out that most people don't actually know 
it, and people get hurt because that which "everyone" knows isn't 
actually something everyone knows. "Why should we have put the safety 
stop on the cutting machine? Everyone is aware of the needed precautions 
when using it."

In my opinion, if someone writes down the "obvious" thing that most 
people don't know and makes sure everyone is _actually_ warned about it, 
they get full credit, because the previous "discoverers" didn't bother 
to tell people in such a way that most people who might come to harm 
would be protected.


Perry