Comments on: Code Cleanup Gone Wrong http://blogs.mcafee.com/mcafee-labs/code-cleanup-gone-wrong Tue, 29 Nov 2011 07:51:20 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Craig Hughes http://blogs.mcafee.com/mcafee-labs/code-cleanup-gone-wrong/comment-page-1#comment-17038 Craig Hughes Fri, 16 May 2008 16:33:11 +0000 http://www.labs.com/research/blog/?p=652#comment-17038 This problem is of course not limited to debian servers, since any SSH server which has a compromised key (possibly generated elsewhere) in a user's authorized_keys file will be vulnerable. All SSH server operators should scan their systems' users immediately for vulnerable keys. I have used the pre-generated vulnerable key lists to run some attempted auths automatedly (and somewhat naïvely) against my own machine, and can run about 50 keys per second with a simple one-line perl script (using ssh-agent to try 7 keys per connection attempt). The openssh daemon only logs the connection attempts, but *not* the failures when you pass a non-valid key. 50 keys/second means the entire 32k RSA-2048 keyspace can be attempted in about 10 minutes against a single server. This could trivially be parallelized in a botnet. If I were to pick a username to try all the keys against, I'd probably suggest something like "root". How long before we start seeing tens of thousands of compromised unix systems out there being added to the botnets? This problem is of course not limited to debian servers, since any SSH server which has a compromised key (possibly generated elsewhere) in a user’s authorized_keys file will be vulnerable. All SSH server operators should scan their systems’ users immediately for vulnerable keys. I have used the pre-generated vulnerable key lists to run some attempted auths automatedly (and somewhat naïvely) against my own machine, and can run about 50 keys per second with a simple one-line perl script (using ssh-agent to try 7 keys per connection attempt). The openssh daemon only logs the connection attempts, but *not* the failures when you pass a non-valid key. 50 keys/second means the entire 32k RSA-2048 keyspace can be attempted in about 10 minutes against a single server. This could trivially be parallelized in a botnet. If I were to pick a username to try all the keys against, I’d probably suggest something like “root”.

How long before we start seeing tens of thousands of compromised unix systems out there being added to the botnets?

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