Raw payload works, but encoded version doesn't

[laxwy at yahoo.com (Whit)]

I just started using Metasploit and its worked great so far.  I'm having trouble, though with the shellcode that is 
being generated after it goes through the encoder.  I'm targeting a custom service on a VM.  I know it's vulnerable.  
I've exploited it with and without Metasploit.  I can only get it to work with Metasploit when I use a raw payload, 
though.

The program segfaults when I use the encoded version of the payload.  I've debugged using GDB and am sure that 
everything leading up to the shellcode execution is correct.  It's a simple buffer overflow that overwrites a return 
address.  It returns to the proper address and continues just fine.  It always gets through the nop sled.  It just 
doesn't ever actually execute the shellcode properly.  I've tried a bunch of different payloads and they all segfault 
as well.

Any thoughts?

Info on the target (VM):
Linux version 2.6.8-1-686 (joshk at trollwife) (gcc version 3.3.5 (Debian 1:3.3.5-2)) #1 Thu Nov 25 04:34:30 UTC 2004


Thanks!



       
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