Re: NASL 'Split' function Buffer overflow Vulnerability

[Renaud Deraison <deraison@xxxxxxxxxx>]

On Apr 25, 2006, at 3:51 AM, OS2A BTO wrote:
> We have discovered a vulnerability in libnasl of Nessus which can
> cause Denial of
> Service. We have attached the advisory which details the  
> vulnerability and
> also has the fix. A patch for libnasl 2.2.4 is included.


At the opposite of what the full advisory hints, this issue is NOT  
exploitable.

On Nessus 2, the program is killed via abort(), on Nessus 3, a  
segfault occurs due to an attempt to read an invalid location of the  
memory (this location is not user-controlled).


There is a denial of service, though. However, the only way to  
exploit it would be to load a rogue plugin in nessusd, which is  
difficult since the plugins downloads are cryptographically signed.


The out-of-memory / bad pointer dereferencement condition will  
nevertheless be addressed in Nessus 2.2.8 / 3.0.3.


                                -- Renaud


ps: OS2A did not contact us prior to releasing this misleading  
advisory. So much for 'responsible disclosure'.