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Feb. 1, 1999
_______________________________________________________________________
Happy Hacker web site http://www.happyhacker.org
Svenska: http://w1.340.telia.com/~u34002171/hhd/gtmhh/svenska/hhdsvensk.html
URL of the day: http://dailynews.yahoo.com/headlines/ap/technology/story.html?s=v/ap/19990121/tc/hapless_hacker_
_______________________________________________________________________

Reader Submissions
A Cup of Java
Firewalls...Again
Perl Corner
Editor's Comments

******************************************************************
Reader Submissions

From:  "Fam. Engelen" <fam.engelen@worldonline.nl>
Hi,

In the last issue of the HHD/Win (Jan. 25) you cover ftp-ing 'by hand'.
A good thing for newbies to get to know the language a bit better is to
take a look at the FTP program 'FTP Explorer'. It has a graphical explorer-like
interface, but you can directly see how you pressing the buttons is
convertred to FTP code. Check it out. (www.ftpx.com)

Arnout

[Editor's Note:  For all of you who are trying to access friend's
Win95/98 shares, and you're getting all sorts of errors, such as
3787, try:

http://www.patriot.net/users/carvdawg/win95.txt      ]

From:  "Rod Johnson" <rjohns@otenet.gr>
**Note:  Rod sent this email encrypted via PGP.  Great job, Rod,
and thanks for reading the Digests.  Now, would you mind sending
along _your_ key?

I tried out the HH info on netstat a couple of weeks ago.  It worked
just the way it was supposed to but since I did not know that much
about IP etc, I quit playing.  After much reading, I went back to try
netstat, ping etc agian.  Imagine my surprise when Win98 kept telling
me the programs were performing illegal operations and were being shut
down.  Since I had installed MS mail and faxing, I thought that was
the problem.  When I removed the faxing and mail, no dice.  I then
appealed to the newsgroups for advice, only silence.  I removed all
networking, adapters etc and reinstalled them.  Nothing.  Then I
explored the CAB#8 and extracted ping.exe to a temp directory.
SURPRISE! the ping I extracted was 8 KB smaller than the ping on my
system.  The ping I extracted manually worked just fine. Then I
checked netstat and found the same thing.  I then manually checked
each executable in the CAB and found that the files on my disk were
all exactly 8 kb larger.

ARP.exe
FTP.exe
IPCONFIG.exe
NETSTAT.exe
PING.exe
TRACERT.exe

Unfortunately, I didn't think to keep the larger files, I just
overwrote them with the files from the cab.

Any thoughts?

Rod

[Editor:  Hhhhmmm...I don't know.  You said you installed
fax and mail...did you install anything else?  I don't know if
you were infected with anything, but you may have gotten bad
copies of files or something...]

From:  Jonah <jonah.braun@schoolofhope.org>

Hello.  I have been reading the HH digest for quite some time now and
decided to ask a question.  If this isn't the right address to do
that...
my apologies!

Anyway, my question that I would like you to cover in the digest
is a bit of info about being a server.  That's pretty general and
probably naive, but anyway.  Specificly, I want to have port 80
open on my computer and be able to have people type in my ip
address and serf there!  Is this possible at all on a win95 box?

Thanks for your time,

Joe E. B.

[Editor:  Joe, yes, it is possible...if you have a web server
installed.  Keep your eye on future Perl Corners...we'll be dealing
with servers!!]

From:  Mullder85@aol.com

thank you for taking the time to read this. i have a few questions.
1 where can i get info on programing and free software? I am
intrested in learning.
2 how do i use eudora pro with aol how do i find out smtp and
the hole aol name??
3 how do i get free easy to understand info on hacking like the
happy hacker witch is (my bible)? thank you!

[Editor:  1.  Well, we have been covering programming and giving
away free software here in the HHD.  2.  I don't know if you can use
Eudora with AOL.  Maybe one of our other readers can help.  3.  Uhm...
stay tuned!!  Oh, and please be more careful with the spelling...I
don't know that Carolyn will appreciate the reference in the last
line...  ;-)  ]

From:  nickord <nickord@netcologne.de>

Dear Carolyn,

I sent you a question recently concerning Netbus and BO and whether
sommething like McAffe virus scan would defend against them. However !
That bit in the new windows digest on Perl and how you can see if they
are there is brilliant ! Maybe I still don´t understand the difference
between a straight virus and BO, but putting two and two together, it
looks like a virus scanner won´t deal with BO and Netbus, but you can
check them out yourself with what you showed today . Thanks,

Nick

[Editor:  Thanks, Nick!  Glad you found something to be of use.
Some virus detection firms have jumped right on top of the BO issue
and can 'detect' it...though how they do so, I have no idea.  But if
you read up on BO and NetBus, you'll find out what the 'fingerprints'
are for each.  Any readers want to contribute about any of the other
'trojans' besides NetBus and BO?  Signatures, files, default ports,
anything?]
 

From: "Marc S. Hernandez" <sushix2@gate.net>

hello, im subscribed to the Happyhacker comlumn

I have a question.....is it possible to open another pc's CD-ROM
remotely with a script or command....It has to be because a friend
of mine downloadied a canned hacking tool and it worked...the only
problem with canned programs id that i dont trust them....

I was wondering if you knew if this was possible to do it manualy
....if you do.  how - so?

Thanks
Marc S. Hernandez

[Editor:  yes, Marc, there is a way.  Of course, I think we all
know how to do this manually...push the button.  But ever since Coca
Cola came out with a nifty little .exe that offered the user a
free cup holder as a promotion...and neatly opened their CD-ROM
drive...other little gems from the Net have been offering the same
functionality.  Namely...BO, NetBus, etc. ]

From:  "Bob" <ulysses@twcny.rr.com>
Subj:  FTP Hacking

I read a short file on getting root access to an FTP using three easy
commands, after hitting enter at both the login and password prompts:

quote user ftp
quote cwd ~root
quote pass ftp

I've tried this several times, and it has only worked twice; once on an
already completely public FTP, and the second, well, it still said I
didn't have enough credits to download. Obviously that isn't right,
'cause it's suppose to be root access. Most of the time I either just
get disconnected, or a "bad sequence of commands" type error. Is there
a better way to get access to an FTP, if not, just a different way?
Sorry to bother you
~Bob

[You can got to jail warning!  Get permission to try to break into a
computer before you try this ftp server trick.  Use koan.happyhacker.org,
fishbone.happyhacker.org, or smurfette.happyhacker.org, they are all legal
targets.  Or get a friend to give you permission to break into his computer.
-- Carolyn Meinel]

[Editor:  I ran across this file a while ago, and tried it out
on a couple of ftp servers.  Like you, I found that it didn't
work on everyone, and I also found it to be more successful when
I took out the middle command.  I suspect that what happened here
is that the person who wrote the file found that it worked once
on a very, very badly misconfigured server...and then posted it
as a guaranteed method of getting root.  If any of our readers
would care to write up an explanation of what the commands do,
and maybe do some legal testing of the sequences, I'd be more than
happy to post it here...]

******************************************************************
A Cup of Java

I've received a few emails about Java, mostly from people asking
how to start programming in Java.  Okay, I thought I would just
present a little taste here (without a biscotti...  ;-)  )  and
see what the reactions of our readers are...eh...is...whatever.

The best place to get started with Java is from the people who
brought you JAVA!!

http://www.javasoft.com

If you're interested in tutorials, links, games (there's even
a version of Tron in Java!!) then drop by the Yahoo site, and
follow the links...Computers -> Programming Languages -> Java.

******************************************************************
Firewalls...Again

After the last HHD for Windows, I received several emails asking
about how to get around firewalls and proxy servers.   So I
thought I would revisit the subject briefly to clarify a point or
two...

First, a proxy server is a sort-of firewall, in that it can be
used to perform some of the functions of a firewall.  Now, this is
not to say that MS-Proxy 2 is as good a firewall as, say,
WatchGuard's FireBox or NAI's Gauntlet.  No, I am not here to
rate firewalls and similar products.

Usually when a company installs a firewall, it puts the firewall
on the connection out onto the Internet, so that all traffic
going either to or from the Internet must pass through it:

   Internet  <--> [ Firewall ] <-->  LAN

Now, this isn't always the case...but this is generally how it
happens and how it should be.

Many readers ask me if they are on the LAN, and they want to
surf hacker sites on the web, and the firewall blocks them from
doing that...how can they surf the hacker sites?

Well, as I pointed out in the last HHD...if the firewall is
configured properly, you can't.  Not *through* the firewall.
Your options include:  wait to do your surfing when you get
home, or install a modem (**NOT RECOMMENDED AT ALL...but it is
a solution).

******************************************************************
Perl Corner

NOTE:  To best experience this edition of the Perl Corner, I
strongly suggest that you read through the article first,
then copy the files that are listed here over to a directory.
I am using "c:\perl\md5" here...but whatever you wish to use
is up to you.  Then, go back through the article again, this
time looking at the files and scripts, and making any changes
as you go...

In this edition of the Perl Corner, we're going to build a non-
real-time intrusion detection system!!  But before we do that,
we need to go over a few concepts, and get a couple of things set
up.  At this point, I am going to assume (I know, it's a dangerous
thing to do!!) that everyone has ActiveState's ActivePerl build
509 installed...well, you don't need exactly build 509, as an
earlier build will do.  If you don't, then go to:

http://www.activestate.com

and follow the links for the latest build.  Download and install
ActivePerl, and for Win95/98 users, make sure that you PATH is
correct.  To do this, start by typing "set" at a command prompt,
and look for the "PATH" environment variable.  If you don't see
"c:\perl\bin" in that statement (you should see "c:\windows" and
"c:\windows\command"...), then go to the command prompt and type:

c:\>notepad autoexec.bat

Now, add the line:

PATH=%PATH%;.;c:\perl\bin

...and save the file.  The "." tells the environment to look in
the current working directory (whichever one you're in) and the
"c:\perl\bin" tells the environment to look in...well, that
directory...when searching for commands.  Your Perl interpreter,
"perl.exe" is in "c:\perl\bin".

Now, reboot.  Of course, you could just type "autoexec.bat" at
the prompt, but that would only update the environment for that
session.

For NT users...all you should need to do is update your
environment via the System icon in the Control Panel.

Okay, by now I hope we're just about ready to get started.  Now,
we need to talk a little bit about what we're going to be doing.
As we all know, one thing that intruders like to do to systems is
alter files.  For example, add something like "deltree /y c:\"
to the autoexec.bat file...which is bad, VERY BAD!!  On Unix
systems, there are rootkits that trojan many of the commands,
such as ls, ps, etc, so that they perform some additional function.
So, one thing we can do to detect that someone has been
intruding in our system is by detecting changes in specific
files.  There is a system for Unix called "Tripwire" that does
just that.  So what we are going to do is use ActivePerl to build
a rudimentary intrusion detection system for Win95/98/NT.

So how do we detect changes in files?  Well, let's look at what
we have available.  Part of the error checking used by TCP/IP is
something called a checksum.  A checksum is generated for header
or data information, using a mathematical function, so that
when the receiving end gets the data, it also generates a checksum.
If the checksums match, the data is considered to be free of
errors.  One such function that can be used to generate checksums
in general is the MD5 checksum.  I won't go into any detail about
the MD5 checksum...that's something for the reader to investigate!

The first thing we need to do is get the MD5 module for Perl.  I
haven't found that it comes as part of the default install...but
not to worry!  It's really easy to get...just follow these simple
instructions:

1.  Go to:  http://www.activestate.com/packages/zips
2.  Locate and download the file "MD5.zip".
3.  On your local system, create a directory called
    "c:\perl\mods".
4.  Using Winzip, extract the contents of MD5.zip into the new
    mods directory...make sure that you tell Winzip to use the
    directory structure in the archive.  Now, you should have,
    at least, a ".ppd" file and a readme file in the mods dir,
    and another directory called "x86".  This directory will
    contain another zipped archive.
5.  Go to a command prompt, change to the c:\perl\bin dir, and
    type "ppm".  This will put you in the Perl Package Manager,
    in interactive mode...your prompt will now look like "ppm>".
6.  At this prompt, type:  "set repository LOCAL c:\perl\mods".

NOTE:  For all the skript kiddies and newbies...in the Perl Corner,
spelling is VERY important!!

7.  Again at the ppm prompt, type "install MD5".  Choose "y" when
    prompted...and wait.

If you don't get an error message at this point...you might have to
wait a couple of seconds, the package should be installed.  To see
if this is the case, type: "query MD5" at the prompt, and you should
see "MD5" as the response.  NOTE:  Type "help" to see what the
various commands are...

Okay...we should be just about ready to get started.  Now, for
this project, we're going to use a couple of different parts.
This is how the project will be set up:

1.  We're going to have a list of files that we're going to
    check.  This is going to be our configuration file.
2.  We're going to have a Perl script that will go through the
    config file and for each file, will generate an MD5 checksum
    and save that, with other info, to a log file.
3.  We're going to have a second Perl script that will go through
    the log file and verify that each checksum is correct.  If
    not, a message will be printed to both the screen and to
    a separate log file.  If everything checks out fine, then
    a message to that effect will be printed to the screen.

Note:  The important thing to remember here is that the config
file should consist of files that are not expected to change.
This includes autoexec.bat and config.sys for Win95/98 systems,
web pages (if you're running a web server), system files, etc.
If any of these files do change, then you need to re-run the
script to generate the checksums, so that the log file is updated.

**NOTE:  A couple of things I want to point out here...first,
if we were writing these files for NT only, we could very easily
send all messages to the Event Log, rather than to a separate file.
But as we're writing it for 95 and 98 as well, we have to use
the files.  Also, there is nothing in this project that is specific
to Windows...so these files can be run on any system that has
Perl (and the MD5 module, of course) installed...including Linux,
Amiga, Mac, etc!!

Our first file is called "filesentry.pl".  I've provided comments
in the code to explain what's going on:

-----  begin filesentry.pl  -----
#! c:\perl\bin\perl.exe

# Make absolutely sure that the preceeding line is
# the FIRST line in the file...all the way at the
# top, with NO blank lines prior to it!!

# Okay, these are the modules we want to use
# We installed MD5 previously, and the stat module
# is part of Perl
use Digest::MD5;
use File::stat;

# This is a subroutine call that prints some info
# to the screen
usage();

# These are our files that we'll be using.  I've hard-
# coded them for ease of use.  Feel free to change them
# if you like.
$config = "md5_conf.txt";
$log = "md5_log";

# Try to open the files...if we can't we want to quit.
open (CONF, "$config") || die "Could not open config file: $!\n";
open (LOG,"> $log") || die "Could not open log file: $!\n";

# Now that we have the configuration file opened, we'll read
# the lines of the file...which are just filenames with
# complete paths.
while (<CONF>) {
  $file = $_;
  chomp $file;

# The '-d' operator checks to see if the filename is
# really a directory.  If it is, we skip it.
  if (-d $file) {
    print "$file is a directory.  Skipping...\n";
  }
  else {

# The '-e' operator checks to see if the file
# exists...if it doesn't, we can't generate a
# checksum, now, can we?
    if (-e $file) {

# Use the baseline subroutine to generate the
# the checksum.  Also get other information about
# the file, such as size, modification and creation
# date, last access time.  Check the HTML docs in
# Perl for the File::stat function
      $base = baseline($file);
      $size = stat($file)->size;
      $atime = stat($file)->atime;
      $mtime = stat($file)->mtime;
      $ctime = stat($file)->ctime;

# Generate comma-delimited output to the screen and
# to the log file...this makes it easy to separate
# the information in the log file for verification
      print "$file,$base,$size,$atime,$mtime,$ctime\n";
      print LOG "$file,$base,$size,$atime,$mtime,$ctime\n";
    }
    else {
      print "$file does not exist.\n";
    }
  }
}

# Tidy up by closing the files...this is good
# programming practice.
close(CONF);
close(LOG);

# This is our baseline subroutine.  This code was
# taken directly from the HTML docs that were
# generated when we installed the module.
sub baseline {
  my ($file) = @_;
  open (FILE, $file) or die "Can't open $file: $!\n";
  binmode(FILE);
  $digest = Digest::MD5->new->addfile(*FILE)->b64digest;
  return $digest;
}

# My usage subroutine.  This shouldn't change if you plan to
# use and distribute this code.
sub usage {
  print "FileSeNTry, by Keydet89\ncopyright 1998-1999 Keydet89\n\n"
}

-----  end filesentry.pl  -----

Okay, to run this all we need is the config file.  Here's an
example that I used...please notice a couple of very important
things about this file...first, all files are accompanied by
their complete path.  Second, there are NO comments...the only
lines in this file are the paths and filenames themselves.  For
this project to work as is, this must be the case.  However,
you should feel free to modify these files and scripts to meet
your own needs.

Now, here's my config file:

-----  begin md5-conf.txt  -----
c:\tadau.txt
c:\jam.bat
c:\perl.txt
c:\cam
-----  end md5-conf.txt  -----

Notice, I'm keeping things very simple.  I'm using files that I
have on my system for this example.  Feel free to use any files
of your own.

To run this, go to the directory that the files and scripts are
in and type:

c:\perl\md5>filesentry.pl

You'll see the results printed to the screen, but I'll include the
results from my logfile here:

-----  begin md5_log  -----
c:\tadau.txt,Pckmx+Mso6xW/gEd+aDk5Q,6291,917617488,916953603,916953602
c:\jam.bat,/fIJSjyhFTTxJD7kG+gvBQ,53,917617608,907588950,907588950
c:\perl.txt,uF4oQ+6iL4C1KOGO1eaOmQ,596,917617520,908370748,908370748
c:\cam,tmXzIgJ+0agg0WGdmpnEOw,265,917617540,916087470,916087088
-----  end md5_log  -----

Okay, now we've got a comma-delimited log file.  Now let's look
at what we need to do to verify that the checksums are correct.

-----  begin md5ver.pl  -----
#! c:\perl\bin\perl.exe

# We need to use the MD5 module again
use Digest::MD5;

# Print out some text to the screen
usage();
print "This file verifies MD5 checksums.\n";

# Open the files we need to use.
$log = "md5_log";
$warn = "warn.log";
open(LOG,"$log") || die "Could not open log file.\n";

# Notice how we've opened the warning file...we
# are using the redirection operator to open it for
# for writing.  Using ">", the file is overwritten
# each time...to save warnings cumulatively, use ">>"
open(WARN,">$warn") || die "Could not open warning file.\n";

# Loop through the log file, reading in the info
# from each comma-delimited line.
while (<LOG>) {

# Notice how easy it is for us to separate
# the items in the comma-delimited file
# using the split() command.
  ($f,$md,$size,$atime,$mtime,$ctime) = split(/\,/);
  if (verify($f,$md)) {
    print "$f verified.\n";
  }
  else {

# If a file is found to not have a correct
# checksum, we want it printed to the warning
# file!!
    print "Warning:  $f checksum has changed!.\n";
    print WARN "Warning:  $f checksum has changed!.\n";
  }
}

# Tidy up a bit by closing the files
# Again...good programming practice.
close(LOG);
close(WARN);

# Here's our subroutines.  Notice that
# we re-used the baseline() subroutine
# from filesentry.pl...and why not?  It
# works just fine, and does what we want
# it to do!
sub verify {
  my ($file,$md5) = @_;
  if (baseline($file) eq $md5) { return 1;}
  else { return 0;}
}

sub baseline {
  my ($file) = @_;
  open (FILE, $file) or die "Can't open $file: $!\n";
  binmode(FILE);
  $digest = Digest::MD5->new->addfile(*FILE)->b64digest;
  return $digest;
}

sub usage {
  print "FileSeNTry verify, by Keydet89";
  print "copyright 1998-1999 Keydet89\n\n"
}
-----  begin md5ver.pl  -----

Again, notice that I've commented the file with explanations
of the hows and whys along the way.  Now, when you run this
file:

c:\perl\md5>md5ver.pl

you should see the names of each of the files followed by
"verified".  Ah, but let's test this little script and see
if we can detect file changes.  To do this, open one or two
of the files in your md5_conf.txt file in Notepad, and make
some changes...anything will do.  Now, don't run filesentry.pl
...instead, run md5ver.pl again.  I altered two of the files
in my test config file, and my warning file contains:

Warning:  c:\tadau.txt checksum has changed!.
Warning:  c:\cam checksum has changed!.

Well, those are the files I changed!!  So we've verified that
these scripts do, in fact, detect changes to files.  As an
exercise for the reader, I'll leave it up to you to make
comparisons of file sizes, access and modification times as
part of the check, as well.  That way, you can display the
old settings, as well as the new, in your warning log.

Now, some of the things we've covered here include opening
and closing files, reading to and from files, and some general
Perl things.  As I stated earlier, if you're using NT, it might
be a good idea to send all your warnings to the Event Log.

If anyone is a sysadmin, and uses this example, even as a
starting point, please let me know.  I would like to know the
feasibility of using this example in a networked environment,
with files on mapped shares, etc.

Stay tuned for upcoming editions of the HHD...in the Perl Corner
I plan to cover two subjects.  Next time, we're going to write
some scripts using sockets...for example, we'll write a script to
implement a finger client (this is something the Win95/98 users
will be interested, as those os's don't ship with their own
implementation of a finger client).  After that, we'll create
a server...maybe a finger server, or maybe a server to trick the
skript kiddies into thinking that you've got NetBus running!!  So
read up on TCP/IP sockets!!

_________________________________________________________________


   
 

This is a list devoted to *legal* hacking! If you plan to use any
information in this Digest or at our Web site to commit crime, go away!
Foo on you! Don't email us bragging about any crimes you may have committed.
We mean it. 

For Windows questions, email keydet89@yahoo.com or editor@cmeinel.com
For Unix questions, contact unixeditor@cmeinel.com.
For Macs, email Strider <s.corinth@iname.com> 

Happy Hacker staff: Unix editor, <unixeditor@cmeinel.com>;
Windows editor, Keydet89 <editor@cmeinel.com>; postmasters Jonathan D.
Zerulik and William Lewis <>; Hacker Wargame Director,
Mark Schmitz <wizard@rt66.com>; Wargame Sysadmin, Satori <Satori@rt66.com>;
Grand Pooh-bah: Carolyn Meinel <>

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