F22 System Wide Change: Set sshd(8) PermitRootLogin=no

[Adam Williamson]

On Mon, 2015-01-19 at 14:23 -0500, Miloslav Trmač wrote:
> > On Fri, 2015-01-16 at 15:39 +0100, Lubomir Rintel wrote:
> > > 
> > > There's a chance of a successful exploitation that would result 
> > > in obtaining my privileges. Sure, gaining access to my account 
> > > is bad enough, but if I run "su" or "sudo", they have root!
> > 
> > Along these lines, someone pointed out a rather nasty attack 
> > vector via sudo the other day:
> > 
> > http://blog.grdryn.me/blog/fedora/prank-alias-sudo-in-bash.html
> > 
> > so...you'd better remember to call it with \ every time...:)
> 
> This is a „movie plot threat“, proposing a specific attack and a 
> specific mitigation, but doing nothing about the immediately 
> available alternative attacks.  For example, I could edit ~/.profile 
> to replace the running bash with a modified copy that ignores (or 
> even specifically hijacks) the \ in \sudo.
> 
> At a first glance it seems to me there in principle can’t be a way 
> to protect against a modified shell environment from within that 
> environment because that environment can lie to you about any system 
> output, or to the system about any your input.  (So even having a 
> trusted “antivirus service” running outside of the shell and 
> protected against it wouldn’t be useful because from the shell you 
> could never be sure that you are talking to that trusted service.¹)
>    Mirek
> 

Sure, I just meant it as a handy and clear demonstration of the 
principle that if you can compromise the environment of a user with 
sudo or other admin privileges, you're about 97% of the way to root in 
any case.
-- 
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Twitter: AdamW_Fedora | XMPP: adamw AT happyassassin . net
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