Nmap Development mailing list archives
Re: Ncrack 0.2 Alpha - SSH behaviour
From: Robin Wood <robin () digininja org>
Date: Tue, 31 Aug 2010 12:58:20 +0100
On 31 August 2010 12:49, Mike Westmacott <mike.westmacott () irmplc com> wrote:
Hi, I've been testing ncrack 0.2 and have found some behavior where for some wordlists it will report that a password failed even though it is the correct one yet on others it will be ok. This may be related to the overall size of the wordlist and also to the parallelicty in effect. I was testing against DeICE 1.100 with a username/password that is found as part of the testing against that VM (I will avoid divulging this info on the list!). I was using a 3.3mb wordlist which also contains some symbolic and alphanumeric passwords. If I extract all words that begin with the same letter as the password then I get a match. If I concat that file together to make it >3.3mb it still works. If I put the password at various intervals throughout the original password file it doesn't match (indeed it writes the login failed) - even when it's the first password. By removing parallelism the problem went away. I was only ever testing against 1 explicit user. I can put together a tar of options, results, debug output and the dictionary files - please let me know if you would like to see the results. Overall though I was hugely impressed by the speed although found tweaking the retry delay was essential to getting it working ok (or maybe I was being confused by the problem I have just described - not sure :)
I've not tried ncrack but I am working on an ssh bruteforcer of my own and I've found a problem when testing against openssh, there is a MaxStartups value that governs the "maximum number of concurrent unauthenticated connections" check man sshd_config for more info. I don't know if it was designed to protect against brute force attacks but it does it because if you fire loads of passwords at once then you trigger this limit and all new connections are rejected. The default is 10 connections so when I go parallel I hit this limit fairly quickly, if I go single threaded and put a slight pause in between attempts then I can go through large lists. This may be completely down the wrong track but it worth looking at if it hasn't already been. Robin _______________________________________________ Sent through the nmap-dev mailing list http://cgi.insecure.org/mailman/listinfo/nmap-dev Archived at http://seclists.org/nmap-dev/
Current thread:
- Ncrack 0.2 Alpha - SSH behaviour Mike Westmacott (Aug 31)
- Re: Ncrack 0.2 Alpha - SSH behaviour Robin Wood (Aug 31)
- RE: Ncrack 0.2 Alpha - SSH behaviour Mike Westmacott (Aug 31)
- Re: Ncrack 0.2 Alpha - SSH behaviour Robin Wood (Aug 31)
- Re: Ncrack 0.2 Alpha - SSH behaviour ithilgore (Aug 31)
- RE: Ncrack 0.2 Alpha - SSH behaviour Mike Westmacott (Aug 31)
- Re: Ncrack 0.2 Alpha - SSH behaviour Robin Wood (Aug 31)