Defacing Websites A Step By Step Process By Ankit Fadia Hacking T ruths. FTP Exp

 
 
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Defacing Websites Part I : A Step By Step Process By Ankit Fadia
ankit@xxxxxxxxxx <mailto:ankit@xxxxxxxxxx> 
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Date Released: 29th June 2001
 
In the past I have received a number of queries like: How do I deface
websites? How do I replace someone else's web page with my own? Questions
like these had become very common. After procrastinating this manual for
some weeks, I finally have got down to bringing it out.
 
Before we move on with this manual, it is important to note that this manual
explores only one method of defacing websites and the described process will
not necessarily work on all target systems. Also note that we take an
imaginary target system X for the below steps.
 
Identifying a Vulnerable host
 
A number of system administrators have a tendency to keep even those ports
on their system open, which have no useful daemon running on them. One tip
given to all system administrators is to close all those ports or disable
all those daemons/services, which have no great use. However, many system
administrators around the world are both too carefree and ignorant or lack
the knowledge required to be able to get a list of running services and
disabling the not useful ones. In effect they keep their system vulnerable
to outside attacks by keeping even those ports open, which could have been
done without.
 
The first step to be able to deface a website successfully is to identify a
vulnerable host, against which you can carry out attacks. The defacing
process described in this manual requires for the Port 21 or the FTP port of
the target system to be open and allowing anonymous logins. In effect, you
first step would be to port scan the target system X and find out whether or
not the FTP port is open, and if the FTP port is open, then whether it
allows for anonymous logins or not.
 
When I port scanned X, I find that Port 21 is open and it indeed has the FTP
daemon running. I then use the FTP MS-DOS utility to ftp to port 21 of X.
 
C:\WINDOWS>ftp X
Connected to X
220 X FTP server (Digital UNIX Version 5.60) ready.
User (X:(none)):
 
FTP'ing to the port 21 of the target system brings up a prompt which asks
for a Username. Now, let us try to login anonymously:
 
User (X:(none)): anonymous
331 Guest login ok, send ident as password.
 
The daemon did not get an error message, thus it does allow anonymous
logins. Now, I just enter any fake email address as my password and login:
 
Password: fake_email@xxxxxxxxxxxxxxx
230 Guest login ok, access restrictions apply.
ftp>
 
Actually, one does not need to login anonymously for this method to work.
Even if you have a normal account with the target system, using which you
can login to the FTP daemon and if the system is vulnerable, then this
method will still work. If your target system does not allow anonymous
logins and if you do not even have an account with them, then another thing
that you could try is: Trying to login using the default password of the FTP
daemon running on the target system. (For more information regarding default
passwords, read: http://hackingtruths.box.sk/defaultpasswd.htm
<http://hackingtruths.box.sk/defaultpasswd.htm> ) However, the fact remains
that the method described in this manual works the best with servers, which
have anonymous logins, enabled.
 
The Vulnerability Itself
 
In the above paragraphs, I have mentioned the term: 'the method', several
times. So what exactly is this method and what vulnerability does it
exploit?
 
Ideally, the FTP port should be disabled unless it is really of some use. If
one does have to necessarily keep the FTP daemon running, then typically
each user's file access should be limited to a particular directory. For
example, like my ISP gives an FTP account to each subscriber, with each
subscriber having file access to the following directory:
 
/bin/users/username
 
However, sometimes both anonymous logins and normal logins give the user
access to the entire directory structure. This means that each and every
user can login to the Port 21 of the vulnerable system and browse through
all directories and access all files on that particular system. In such
cases, the attacker tries to lay his hands on the /etc/passwd file. But that
is not we lay the stress on, in this manual.
 
On top of all this, many servers have world write-able directories, to which
all users have access to, due to the above problem. The directories being
world write-able, means that all users can login and upload any files of
their choice onto the target system. Or in other words, anyone can write to
the target system. Thus, you not only have access to all directories on the
target system, but you can save and delete or even replace all files on that
system, just as if it were your local hard disk.
 
********************
HACKING TRUTH: How do I know whether my target system's FTP port gives me
access to world write-able directories? If you are able to upload any file
to the target system, then it probably means that the directory into which
logged in is at least write-able by you.
*******************
 
This vulnerability can be used by an attacker to access the directory where
the pages of the website hosted by the target system are stored. Once the
attacker knows which directory stores the web pages of the target system
then he can easily edit their pages or even replace their entire site with
his own, with the help of a simple command:
 
ftp> mput filename
 
Please note that if you FTP to a system and find that you are able to upload
files, then it could also mean that your particular directory is write-able
by you, while you do not have privileges to write to other directories. Such
a scenario is quite common in the case of Webspace providers, in which each
subscriber is given a particular space to store files or in other words each
other member is given a write-able directory to which he can upload files.
The gist being, having write privileges in one directory does not give you
write privileges in all directories.
 
With this we come to the end of the first in the series of guides to
Defacing websites. Thanks for reading and till the next update, take care. J
 
Ankit Fadia
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