bug#24489: efaq: security risks

[Ted Zlatanov]

On Wed, 21 Sep 2016 17:26:20 -0400 Richard Stallman <rms@gnu.org> wrote: 

>> 2) using an Emacs mail client to view HTML mail is a security risk if remote
>> content is fetched (I think it isn't by default, but this might not
>> apply to every client)

RS> Could you explain why you think it is a security risk?

On Wed, 21 Sep 2016 00:53:13 +0200 Lars Ingebrigtsen <larsi@gnus.org> wrote: 

LI> Glenn Morris <rgm@gnu.org> writes:

>> 2) using an Emacs mail client to view HTML mail is a security risk if remote
>> content is fetched (I think it isn't by default, but this might not
>> apply to every client)
>> 
>> 3) viewing remote HTML content (eg with eww or xwidgets) is likewise a
>> potential security risk.

LI> Do you mean privacy risk?

Images and other resources can carry constructed data and be used as an
execution backdoor through browser or library bugs. The following don't
necessarily apply to Emacs, they are just examples of the variety and
severity of these attacks, which have risen in popularity as direct code
injection has become harder:

http://arstechnica.com/security/2016/05/easily-exploited-bug-exposes-huge-number-of-sites-to-code-execution-attacks/

http://www.pcworld.com/article/2950578/security/microsoft-rushes-out-emergency-security-update-to-fix-critical-windows-flaw.html

http://fortune.com/2016/07/20/apple-security-bug-password-steal-text/

That being said, privacy risks can also become security risks and I think
the FAQ could be extended to include both.

Ted