[TOOL] Tattle - Automatic Reporting Of SSH Brute-Force Attacks

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Date: 9 Jun 2005 11:34:13 +0200

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  Tattle - Automatic Reporting Of SSH Brute-Force Attacks
------------------------------------------------------------------------

SUMMARY

DETAILS

Tattle is a Perl script that crawls through your SSHd logs (usually
/var/log/messages) and finds hosts who've connected to your SSH server.
All hosts who connect to your box, and that are not accounted for in the
exception list, are reported to the point-of-contact for the domain the
host is registered too (where available).

Code:
#!/usr/bin/perl
# tattle by C.J. Steele, CISSP <coreyjsteele@yahoo.com>
# (C)opyright 2005, C.J. Steele, all rights reserved.
#
# NOTICE: you're on your own with whatever 'messes' reporting this sort of
# activity may create...you've been warned.
#
# This script processes log files and attempts to automatically notify
domain
# authorities of machines in their domain that are actively performing SSH
# brute-force attacks. Mangle the variables above the warning to your
liking,
# but it would be adviseable not to venture past the warning unless you
know a
# bit of perl and are comfortable doing so.
#
#
use strict;
use MIME::Lite;
use File::MkTemp;

my $logfile = "/var/log/messages"; #the place where ssh logs to
my $tmpdir = "/tmp"; #for use when we write out our logs
my @exceptions = ( "10.10.10.10", "your.net" ); #domains not to notify of
ssh attacks, i.e. your domains
my $smtp_host = "localhost"; #your mail server
my $smtp_sendas = "your\@email.com"; #a VALID e-mail address to send the
e-mails out as
my $smtp_message = "An attempt to brute-force account passwords over SSH
has been detected by a machine in your domain. Attached are logs
indicating the times and dates of the activity. Please take the necessary
action(s) to stop this activity. If you have any questions, please reply
to this email or contact me at $smtp_sendas."; #the nasty-gram

########################################################################
# DO NOT MUCK AROUND BELOW THIS POINT UNLESS YOU KNOW WHAT YOU'RE DOING
########################################################################

my @offenders = getoffenders( $logfile );

foreach my $offender ( @offenders )
{
 my $tld = gettld( $offender );
 my @addies = getemails( $tld );
 if( scalar( @addies ) )
 {
  my $logpath = writelogs( getlogs( $offender ) );
  foreach my $addie ( @addies )
  {
   #create the email...
   my $email = MIME::Lite->new(
    From => "$smtp_sendas",
    To => "$addie",
    Cc => "$smtp_sendas",
    Subject => "SSH Brute-force Attack",
    Type => "TEXT",
    Data => "$smtp_message"
    );
   #attach our log files/evidence...
   $email->attach(
    Type => 'text/plain',
    Path => $logpath,
    Filename => "$offender.txt"
    );
   $email->send( 'smtp', "$smtp_host" );
   print "I: e-mail sent to $addie ($offender)\n";
  } #end foreach
 } else {
  print "E: no e-mail addresses found for $tld\n";
 } #endif
} #end foreach

exit( 0 );

sub getlogs
# this routine parses the log file and finds entries that match the $mark,
# which is passed in as a parameter, and creates an array, each element of
# which is a matching line of the log, the single array is returned.
{
 my $mark = shift;
 my @logentries = ();
 open( LOG, $logfile ) or die( "$!" );
 while( <LOG> )
 {
  chomp();
  if( $_ =~ /$mark/ )
  {
   push( @logentries, $_ );
  } #endif
 } #end while
 close( LOG );
 return @logentries;
} #end getlogs()

sub writelogs
# this writes the array of log entries passed via args to a randomly
created
# temporary file, the name of which is returned as a single scalar value,
with
# fully-qualified path.
{
 my @logs = @_;
 my $tmpfile = mktemp( "$tmpdir/rptbdgys.XXXXXX" );
 open( OUT, ">$tmpfile" ) or die( "$!" );
 foreach( @logs )
 {
  print OUT $_, "\n";
 }
 close( OUT );
 return $tmpfile;
} #end writelogs

sub getoffenders
# this returns an array of offending hostnames from the logfile, except
those
# who are listed in the @exceptions array.
{
 my $log = shift;
 my @offs;
 open( LOG, $log ) or die( "$!" );
 while( <LOG> )
 {
  chomp( $_ );
  if( $_ =~ /sshd/ and $_ =~ /rhost/ )
  {
   my @e = split( /\s/, $_ );
   my $off = $e[12];
   $off =~ s/rhost\=//;
   $off =~ s/ruser\=//; #why do I need this?
   if( $off ne "" )
   {
    push( @offs, $off ) if( ! isin( $off, @offs ) and ! isin( $off,
@exceptions ) );
   } #endif
  } #endif
 } #endwhile
 close( LOG );
 return( @offs );
} #end getoffenders()

sub gettld
# this returns a single scalar value containing the top-level domain or
# the ip address fed in. This won't work for a site who's address is
# dom.com.co
{
 my $in = shift;
 if( $in =~ /[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ )
 {
  # its an IP address... try reverse lookup, if that fails, return IP
  return $in;
 } else {
  # its a hostname
  my @bits = split( /\./, $in );
  my $bitslen = scalar( @bits );
  if( $bitslen > 2 )
  {
   if( length( $bits[$bitslen-1] ) == 2 )
   {
    # country-level tld
    if( length( $bits[$bitslen-2] ) > 3 ){
     return "$bits[$bitslen-2].$bits[$bitslen-1]";
    } else {
     return "$bits[$bitslen-3].$bits[$bitslen-2].$bits[$bitslen-1]";
    } #endif
   } else {
    # tld
    return "$bits[$bitslen-2].$bits[$bitslen-1]";
   } #endif
  } else {
   return $in;
  } #endif
 } #endif
} #end gettld()

sub getemails
# gets a list of unique email addresses that were returned for as part
# of the domain's `whois` records. The results are returned as a
# singular array.
{
 my $tld = shift;
 my $whois = `/usr/bin/whois $tld`;
 my @emailaddies;
 foreach( split( /\n/, $whois ) )
 {
  chomp();
  if( $_ =~ /[a-zA-Z0-9]*\@[a-zA-Z0-9]*/ )
  {
   # the line had an e-mail address in it...
   my @bits = split( /\s/, $_ );
   foreach my $bit ( @bits )
   {
    if( $bit =~ /[a-zA-Z0-9]*\@[a-zA-Z0-9]*/ and $bit !~ /\@apnic\.net$/ )
    {
     push( @emailaddies, $bit ) if( ! isin( $bit, @emailaddies ) );
    } #endif
   } #end foreach
  } #endif
 }#end foreach
 return @emailaddies;
} #end getemails

sub isin
# this boolean function simply checks to see if an element ($e) is in the
# supplied array (@a) -- it returns 1 if the element is in the array and 0
# otherwise.
{
 my( $e, @a ) = @_;
 foreach( @a )
 {
  return 1 if( $e eq $_ );
 }
 return 0;
} #end isin()

#EOF

ADDITIONAL INFORMATION

The information has been provided by <mailto:coreyjsteele@yahoo.com> C.J.
Steele, CISSP.
To keep updated with the tool visit the project's homepage at:
<http://sodaphish.com/files/tattle> http://sodaphish.com/files/tattle

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