C considered harmful: was Debian attacker may have used new exploit

[Peter Hiscocks]

Dynamic code generation (program writes code then jumps to it) sounds like a
really useful facility for virus writers, trojan horses and worms. In what
circumstance is it necessary to have that capability?

Isn't it much safer to have a rigid demarcation between code generation and
code execution? Then the operating system can do run-time checks on the
thing it's about to execute.

Peter

On Thu, Dec 04, 2003 at 06:46:40PM -0500, Henry Spencer wrote:
> But it's not clear to me that this really improves things much.  If you
> can overwrite control information, e.g. a function return address -- which
> is generally needed to *exploit* an executable stack or heap -- then you
> can always look around for places where you could branch to existing code
> that happens to do what you want.  (For example, functions which do
> dynamic code generation will have a strong tendency to end with the
> sequence "tell the system to make the heap region pointed to by register X
> executable; return".)
> 
>                                                           Henry Spencer
>                                                        henry-lqW1N6Cllo0sV2N9l4h3zg at public.gmane.org
> 
> 
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-- 
Peter D. Hiscocks                         	   
Department of Electrical and Computer Engineering    
Ryerson University,                    
350 Victoria Street,
Toronto, Ontario, M5B 2K3, Canada

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