[foofus-tools] Medusa SSH Module Issue

jmk jmk at foofus.net
Wed Aug 20 09:13:24 PDT 2008


On Wed, 2008-08-20 at 10:38 -0400, Nathan Grandbois wrote:
> Synopsis:
> Medusa SSH scanning module fails after 3 login attempts with the 
> following error:
> ERROR: Failed to retrieve supported authentication modes. Aborting...
> ERROR: No supported authentication methods located.

<snip>

> Conclusions:
> IMHO I think that the thread responsible for reconnecting is failing. 
> Coincidentally, the number of failed attempts tried by medusa, is equal 
> to the number of failed attempts if done manually. I have googled and 
> googled for hints on this, but the only one I get is from some guy in 
> spanish who said it was a stupid problem that he fixed, without actually 
> giving the fix.
> 
> Please, any help would be greatly appreciated.

I've attached a patch with the changes since v1.4 was released. The
module should now restart the connection when the server tells it to go
away after a few failed attempts. Please let me know if this fixes the
problem for you.

> PS> In addition, if I put a successful password in the first three 
> passwords attempted, medusa takes a dump with the following error:
> *** glibc detected *** medusa: double free or corruption (!prev): 
> 0x0805aff0 ***
> Followed by a backtrace and memory map.

It seems that starting with libssh2 0.18, we're occasionally getting a
double free. As a quick fix/hack, I had just commented out the free() in
LIBSSH2_FREE_FUNC. The attached patch contains this hack. If that
doesn't fix the issue, send me a backtrace and I'll take a look at it.

Joe




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