UNIX FOR DOSADDICTED WaReZ PuPPieZ AND THEIR PETS
By Fahad Naeem
Introduction
------------
One of themost common operating systems in existance is Unix. Unix
exists inmany different flavors, from Berkeley BSD to AT&T System V
to SunOs. Basicworking knowledge of Unix is almost essential to a
hacker, asit is the system a hacker is most likely to come across.
If youintend to use the internet at all, or to do any serious
explorationof Telenet, the ability to navigate through Unix is a
necessity. (Unixis also the single most interesting system in
existance: it'sjust fun to fuck with).
Unix Logins
-----------
Most Unixlogins look essentially the same. A general Unix login
prompt lookssomething like this:
connected tofive.finger.com
login:
That firstline is the system identifier. Although it's not at all
essential towhat you are doing, it's good to know what system you are
attemptingto log on to.
The secondline is what typically identifies the system you are on as
Unix. Almostall Unix systems greet a user with the same prompt:
login:.
Well,there's not much to do in Unix from the outside, and Unix
systems aretypically fairly secure at this point. You may be able to
obtain alist of users, or current users, by logging in as 'who', but
other thanthat there are few functions available here.
Unless youare on the internet, or have accounts specifically for the
specificmachine you are on, the only way on to the system is to try
the defaultpasswords. What are the default passwords?
Unix systemscome installed with certain passwords automatically. In
addition,some accounts must exist on a system. One such account is
'root'. Thisuser is the divine Kami of the Unix system... in short,
an allaccess pass. Unfortunately, few systems allow root logins
remotely,and even fewer leave 'root' unpassworded. Nevertheless, it's
always wortha shot... try this:
connected toren.stimpy.net
login: root
password: root
invalidlogin
login:
well, nicetry anyways... other possible passwords for root include
'sysadmin','sys', 'admin'... you get the idea. You may also want to
try thesepasswords with a single digit appended (added, idiot) to
them... meaningthe password 'root' could be 'root1' or 'root2'.
Aninteresting tip about passwords in general... many people that use
passwordsunder 8 characters tend to add a digit or a non-alphanumeric
character tothe password. This is done in order to hinder guessing,
and to stoppassword breakers (more on this later). In this case, you
may want totry adding a space before root... or even an ascii 255 to
the end.
Fortunately,there is more than one default password in a unix
system... aquick list:
sys sys
bin bin
daemon daemon
rje rje
setup setup
uucp uucp/nuucp/anonymous
nuucp uucp/nuucp/anonymous
mountfsys mountfsys
In theSystem
-------------
Ok, at thispoint, I'm going to assume you've gotten past the login...
as painfulas that may sound. Although Unix may be secure from the
outside,without effort from the system administrators, the inside of
the systemis not.
First off,you'll likely by asked for a terminal. vt100 serves your
purposessufficently, and it's typically the default, so hit enter.
Now,hopefully, you have a prompt. There are many different types of
unixprompts, some of which contain current directory information,
some ofwhich are just a single character. Just don't panic when my
examplesdon't look exactly like what you've got on your screen.
The firstthing you *need* to do on the system is establish your tty
paramters. Aseldritch and arcane sounding as this term may seem, it's
actuallyquite simple... you need to tell the system what keys are
going to dowhat.
The commandto set these parameters is 'stty'. Watch:
squinkyB ] sttyerase ^h
squinkyB ]
There... thatwasn't so bad, was it? Well, it's also pretty
meaninglessto you, unless you have the ascii table memorized and are
pretty goodat on-the-spot deduction.
The ttyerase parameters determines which key is to be used as a
backspace. Attimes, this may already be set when you log in, or it
may be setto a suitable alternate (such as delete). Most of the time
the systemwill tell you when you log on if this is so. In this case,
we'veentered ^h in order to make the backspace key, appropriately
enough,backspace.
Anotherextremely important parameter is 'intr'. The 'intr' paramter
tells theUnix system what you intend to use as a break character...
you shouldhave this set to ^c.
GettingAround
--------------
A good thingto remember about Unix is that it's alot like DOS. Files
are laid outin directories just as in DOS... in fact, the only
immediatedifference in the directory structures is that Unix uses a
forwardslash ("/", moron!) instead of a backwards one.
Also, thebasic Unix directory navigation command is identical to DOS.
In order tochange directories, you use the command 'chdir', or 'cd'.
A quickexample:
1 /usr1/astoria] cd ..
2 /usr ]
Wala. Thatsimple. Quick notes:
ю cd / willtake you to root.
ю cd /*pathname*will take you to *pathname*
ю cd homewill take you to your home directory.
You can makeand delete your own directories with the mkdir/rmdir
commands. Simplyput, mkdir makes a subdirectory off of the current
directory,and rmdir removes a subdirectory from the current
subdirectory.Good to know if you plan to do a lot of file transfers.
An importantnote about Unix directories, files, and concepts:
Unix is acase-sensitive operating system. Thus, the files
ю Spleen
ю spleen
ю SPLEEN
ю SpLeEn
are alldifferent. This rule applies to directories and command line
paramters,as well as most other Unix ideas.
Another nicething to know about Unix: Unix files are not subject to
the normalDOS 8 character limit. Thus, you can have vast filenames,
such as "this_file_ate_my_biscuit".
Some otherimportant commands
-----------------------------
First andforemost, you should know cp. cp is the basic Unix
equivalentof the DOS COPY command. The command line for cp is
identical tothat of COPY.
Next on thescale of cosmic import is cat. cat is the Unix equivalent
of the DOSTYPE command, and once again, for simple file displaying,
the commandline is identical.
Variationson the theme:
pg: displayesa file page by page. Type "pg x filename", where x is a
numberof lines to display before pausing and filename is the
fileyou wish to display.
more: displaysa file screen by screen.
Stupid pettrick:
You can useyour cat to copy files, simply by using the directional
operators. Tocopy a file from here to there using cat, simply type:
% cat here
this is thefile here
% cat there
this is thefile there
% cat here> there
% cat there
this is thefile here
Theoperator ">" simply takes the output from the cat command and
places isin the location specified after it.
Anothervital command to know is 'rm'. rm deletes a file from the
system, inthe same way DEL would on a DOS system. Not to much else to
say.
Critical inyour navigation of a Unix system is the ls command. ls is
DOS DIR onheroin. Simply type ls and you get a nice, neat list of
files in thedirectory.
DIR oncontrolled substances:
There are afew command line parameters that you should know...
foremost isl. ls -l gets you a list of files, and valuable
informationabout each file, including permissions (more on that
later),size, and linked files.
Anotheruseful command for long file lists is C. ls -C gets you a
list offiles in multiple columns, much the same as DIR /W would
merit adouble column report of all existing files. A quick reminder:
ls -C isNOT the same as ls -c. Unix = case sensitive.
Another goodcommand to know, mv will move a file from directory to
directory. Forthose of you without DOS 6.0 <gasp>, mv simply copies a
file toanother directory and deletes the original.
quick tipfor files on the lam:
if you wantto rename a file (to protect the innocent), you need to
mv a fileto a different file name. A quick demo:
# ls
myfile
# catmyfile
this is myfile
# mv myfilemy_other_file
# ls
my_other_file
# catmy_other_file
this is myfile
Anothervastly important command is 'man'. In fact, man is probably
one of themost important commands extant for a beginning user... it
calls up thesystem's help files. To use man, simply type in 'man
command',where command is a Unix command you seek to gain
enlightenment regarding. It's a great way to gain an understanding of
Unixcommandline parameters.
If you areinterested in seeing who's been on of late, or just want a
few names totry to hack, type 'who'. You get a quick list of users
that haveaccessed the system lately. If you <god forbid> need to know
who you areat this point, type 'whoami'.
If you wantto change your identity on the system, type 'su name'
where nameis an account on the system. It'll ask you for the account
password,then, *presto*... instant transmogrification.
A Caveatfor smart alec hackers:
Unixtypically logs usage of the su command. While su may seem like a
greatopportunity to try to hack out passwords manually without
worryingabout the system hanging up after 3 attempts, it's typically
not a goodidea to do this, as it may alert the administrators to
yourpresence.
*Numero Unoon the list of commands NEVER to use on a Unix system:
The 'passwd'command changes your password on a Unix system. Seems
innocousenough, eh? Uh-uh. If your account is active, and there's a
very strongchance that it either is or will be, there is no better
way to losethe account than to change the password, only to have the
legitimateuser alert the sysadmins when he/she can't gain access to
his/hernormal account (well, there are better ways... you could
simply mailthe sysadmin and tell him you are trying to hack his
grandmother's life support machine through your account).
I've seenthis single, quick command turn a extremely lax system
into anironclad security compound in less than a day.
DONT-FUCK-WITH-IT.
*Numero Doson that same list:
The 'mail'command reads and sends mail. So what? Well, unless your
account isstable (and it isn't unless you either paid for it or
killed theoriginal owner in such a way that his body cannot claw it's
way out ofit's grave to it's keyboard), the user is more likely than
not going toknow if you read his mail. In addition, if you send mail
out of thesystem (type 'mail', and a username/address; type in your
message andend it with a ^d on it's own line), the response from your
message willlikewise alert the user to your presence.
SystemSpelunking
-----------------
The firstplace you want to check out in the wild uncharted directory
tree of yourfriendly neighborhood Unix system is the "/etc"
directory. What'sin it? The single most intensely important file on
the system (besidesa world writable root owned SUID file... but don't
worry aboutthat)... the passwd file.
What is inthe passwd file?
ю a list of all accounts on the system
ю a list of the passwords for these accounts
ю a list of access levels for these accounts
ю a list of the home directories for theseaccounts
ю a list of information pertaining to theseaccounts.
Why the hellthe Unix designers decided this file should be world
readable isbeyond me. Be content to know that your standard everyday
run-of-the-mill-lacking-in-certified-cosmic-power'cat' command WILL
display thisfile. As will pg and more. However, because most users
don't havewrite permissions (more on that later) to the /etc
directory,'cat' is pretty much the only applicable command here.
However, ifyou need to copy the file to your own directory (for
whateverreason), just cat it there with the directional operator (>).
The catch:
Well, thereare two catches here. First off, regardless of system
security, ifthe passwords are in the file, they are encrypted. You
can't decryptthem. Although you can get a list of accounts without
passwordsthis way (just look for accounts with no entry in the
passwordfield), and a list of accounts that can't be logged onto
remotely/atall (NO LOGIN), you can't get much else. Sucks, don't it?
Notice Isaid 'if' the passwords are there.
<ominoussoundtrack please>
Somehorrible, paranoid, draconian system administrators mutilate
their passwdfiles in such a way that (*gasp*) the passwords don't
show up. Allyou get is one cold, icy X staring at you from the bowels
of UnixShell Siberia, mocking you as you pull your hair out in
frustration (sorry,but this is a sore spot with me). The kidnapped
passwordsreside in the shadow file in the /etc directory, available
with yourstandard everyday run-of-the-mill-but-distinct-in-the-fact-
that-only-root-level-accounts-can-use-it-to-this-extent'cat' command.
Well, if thepasswords are encrypted, what good are they?
Bythemselves, nothing. A account with a Unix encrypted password will
get you nofurther than an account with no listed password at all. You
can't evendeduce the amount of characters in the password if it's
encrypted. Sowhat's the use?
The Unixmethod of encrypting files is available to the public. It is
also, tomost mortals, irreversable. Essentially, this means you can
encrypt astring of characters, but not decrypt it. Even the unix
systemitself doesn't decrypt the password when you log on...
When you logon, the Unix system takes whatever you enter at the
passwordprompt, encrypts it, and matches it to the entry in the
passwd file.Thus, the Unix system never decrypts the password... it
onlycompares it to a different encrypted string.
While thismay not sound too particularly useful at first, it is.
There areprograms that have been written to do the same thing on a
personalcomputer... you supply it a list of passwords and a list of
words toattempt to use as passwords (called dictionaries), and it
spends thenight encrypting dictionaries and matching them to password
entries. Byrunning a dictionary through a passwd file, on a typical
system, youcan usually get 10-20 accounts. Good personal computer
examples ofthis program idea include Killer Cracker (the industry
standard, soto speak) and CrackerJack (faster than Killer Cracker).
Quick tipsfor CrackerJunkies with leech access at an H/P BBS:
A standarddictionary will not uncover passwords protected with an
appendeddigit or non-alphanumeric character. In order to get around
this, youneed only grab a program that processes the dictionary file
to add thatdigit to each entry in the dictionary... although this
takeslonger, and you'll need to do it multiple times, you can
typicallyget 10 more accounts just by adding a 1 to every entry.
Files anddirectories in Unix are characterized further by their
permissions.Permissions are a standard system of who gets access to a
specificfunction of that file or directory. Standard permissions
includeread, write, and execute. You can get a list of permissions by
typing 'ls -l'.The first field in the listing contains the
permissions,grouped as follows:
owner group world
--------------------
rwx rwx rwx
(Not drawnto scale... in fact, it doesn't look anything like that).
Essentially,as long as the letter is there, you have access to that
facet of thefile. If the letter is not there, you'll see a dash...
meaning youdon't have access to that function. An example:
rwxr-x--x
In thiscase, the owner of the file can Read the file, Write to the
file, andeXecute the file; members of his group (a bunch of linked
accounts) canRead the file, CANNOT Write to the file, and can eXecute
the file;and the rest of the user population CANNOT Read or Write to
the file,but CAN eXecute the file.
rwx---rwx
is a WORLD-READABLE,WORLD-WRITABLE, WORLD-EXECUTABLE file. This
simply meansthat anyone can read, write, or execute the file.
Anotherpermission sometimes set to a file is the SUID bit. An SUID
filecontains a smallcase s in the user executable section of the
permissionslist...
rws--x--x
When youexecute an SUID file, your user ID becomes that of the owner
of the file.While this may not look to important at first, by now you
should knowthat no really important super elite hacker concept does.
Take a lookat this:
rwsr-x--x
Synopsis?It's a world executable SUID file. In essence, anyone can
execute thefile, and in doing so, become the owner of the file for
the durationof the time that file is operating. However, this doesn't
get youmuch, because you typically can't do anything while the
programisrunning. More likely than not, it's calculating how many
pencils itneeds to order for school tomorrow or some other such
drivel.
The realpower of the SUID file comes into play in this situation:
rwsrwxrwx
You won'tsee a lot of these, but when you do, look out. What you have
here is aworld writable SUID file... and a world writable program can
be anyprogram on the system you have read access to. Like, say,
/bin/sh... theUnix shell...
Quickcommand line example... 'diablo' is a root owned, world writable
SUID file. I'mgoing to ignore the rest of the output of the ls
command.
#ls -l
rwsrwxrwx......diablo
#cat /bin/sh> diablo
#diablo
$
Oh, just soyou know, the $ prompt denotes root access.
Good deal,huh? In general, if you have right privs to an SUID file,
copy it toyour own directory and cat /bin/sh into it. You now have an
instantgateway to the account of the owner of that file.
If you wantto find files that you can do this with, try this out:
#find / -userroot -perm -4000 -exec /bin/ls -al {} ";"
This willgive you a list of all root owned SUID files. If you want
more info onthe 'find' command, just 'man find'.
Well, I'moverdo for an appointment on the IRC in #warez... so I'll
cut off here.I hope I've been of assistance to you.
----------------------------------------------------------------------------
A C T U AL A R T I C L E E N D S H E R E . . .
Please feelfree to save an extra 1k of file space and invoke the DOS
EDIT CUTcommand at the dotted line. Do not remove the rest of this
article onpenalty of law.
S00P3R GR00P-3SQU3GR33TZ / +HANX
Greets goout to Nowhere Man, INC, THG, UNT, SaD, SoD, PTA, SOB
Thanks to...________________________
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UNIX FOR DOSADDICTED WaReZ PuPPieZ AND THEIR PETS
Introduction
------------
One of themost common operating systems in existance is Unix. Unix
exists inmany different flavors, from Berkeley BSD to AT&T System V
to SunOs. Basicworking knowledge of Unix is almost essential to a
hacker, asit is the system a hacker is most likely to come across.
If youintend to use the internet at all, or to do any serious
explorationof Telenet, the ability to navigate through Unix is a
necessity. (Unixis also the single most interesting system in
existance: it'sjust fun to fuck with).
Unix Logins
-----------
Most Unixlogins look essentially the same. A general Unix login
prompt lookssomething like this:
connected tofive.finger.com
login:
That firstline is the system identifier. Although it's not at all
essential towhat you are doing, it's good to know what system you are
attemptingto log on to.
The secondline is what typically identifies the system you are on as
Unix. Almostall Unix systems greet a user with the same prompt:
login:.
Well,there's not much to do in Unix from the outside, and Unix
systems aretypically fairly secure at this point. You may be able to
obtain alist of users, or current users, by logging in as 'who', but
other thanthat there are few functions available here.
Unless youare on the internet, or have accounts specifically for the
specificmachine you are on, the only way on to the system is to try
the defaultpasswords. What are the default passwords?
Unix systemscome installed with certain passwords automatically. In
addition,some accounts must exist on a system. One such account is
'root'. Thisuser is the divine Kami of the Unix system... in short,
an allaccess pass. Unfortunately, few systems allow root logins
remotely,and even fewer leave 'root' unpassworded. Nevertheless, it's
always wortha shot... try this:
connected toren.stimpy.net
login: root
password: root
invalidlogin
login:
well, nicetry anyways... other possible passwords for root include
'sysadmin','sys', 'admin'... you get the idea. You may also want to
try thesepasswords with a single digit appended (added, idiot) to
them... meaningthe password 'root' could be 'root1' or 'root2'.
Aninteresting tip about passwords in general... many people that use
passwordsunder 8 characters tend to add a digit or a non-alphanumeric
character tothe password. This is done in order to hinder guessing,
and to stoppassword breakers (more on this later). In this case, you
may want totry adding a space before root... or even an ascii 255 to
the end.
Fortunately,there is more than one default password in a unix
system... aquick list:
sys sys
bin bin
daemon daemon
rje rje
setup setup
uucp uucp/nuucp/anonymous
nuucp uucp/nuucp/anonymous
mountfsys mountfsys
In theSystem
-------------
Ok, at thispoint, I'm going to assume you've gotten past the login...
as painfulas that may sound. Although Unix may be secure from the
outside,without effort from the system administrators, the inside of
the systemis not.
First off,you'll likely by asked for a terminal. vt100 serves your
purposessufficently, and it's typically the default, so hit enter.
Now,hopefully, you have a prompt. There are many different types of
unixprompts, some of which contain current directory information,
some ofwhich are just a single character. Just don't panic when my
examplesdon't look exactly like what you've got on your screen.
The firstthing you *need* to do on the system is establish your tty
paramters. Aseldritch and arcane sounding as this term may seem, it's
actuallyquite simple... you need to tell the system what keys are
going to dowhat.
The commandto set these parameters is 'stty'. Watch:
squinkyB ] sttyerase ^h
squinkyB ]
There... thatwasn't so bad, was it? Well, it's also pretty
meaninglessto you, unless you have the ascii table memorized and are
pretty goodat on-the-spot deduction.
The ttyerase parameters determines which key is to be used as a
backspace. Attimes, this may already be set when you log in, or it
may be setto a suitable alternate (such as delete). Most of the time
the systemwill tell you when you log on if this is so. In this case,
we'veentered ^h in order to make the backspace key, appropriately
enough,backspace.
Anotherextremely important parameter is 'intr'. The 'intr' paramter
tells theUnix system what you intend to use as a break character...
you shouldhave this set to ^c.
GettingAround
--------------
A good thingto remember about Unix is that it's alot like DOS. Files
are laid outin directories just as in DOS... in fact, the only
immediatedifference in the directory structures is that Unix uses a
forwardslash ("/", moron!) instead of a backwards one.
Also, thebasic Unix directory navigation command is identical to DOS.
In order tochange directories, you use the command 'chdir', or 'cd'.
A quickexample:
1 /usr1/astoria] cd ..
2 /usr ]
Wala. Thatsimple. Quick notes:
ю cd / willtake you to root.
ю cd /*pathname*will take you to *pathname*
ю cd homewill take you to your home directory.
You can makeand delete your own directories with the mkdir/rmdir
commands. Simplyput, mkdir makes a subdirectory off of the current
directory,and rmdir removes a subdirectory from the current
subdirectory.Good to know if you plan to do a lot of file transfers.
An importantnote about Unix directories, files, and concepts:
Unix is acase-sensitive operating system. Thus, the files
ю Spleen
ю spleen
ю SPLEEN
ю SpLeEn
are alldifferent. This rule applies to directories and command line
paramters,as well as most other Unix ideas.
Another nicething to know about Unix: Unix files are not subject to
the normalDOS 8 character limit. Thus, you can have vast filenames,
such as "this_file_ate_my_biscuit".
Some otherimportant commands
-----------------------------
First andforemost, you should know cp. cp is the basic Unix
equivalentof the DOS COPY command. The command line for cp is
identical tothat of COPY.
Next on thescale of cosmic import is cat. cat is the Unix equivalent
of the DOSTYPE command, and once again, for simple file displaying,
the commandline is identical.
Variationson the theme:
pg: displayesa file page by page. Type "pg x filename", where x is a
numberof lines to display before pausing and filename is the
fileyou wish to display.
more: displaysa file screen by screen.
Stupid pettrick:
You can useyour cat to copy files, simply by using the directional
operators. Tocopy a file from here to there using cat, simply type:
% cat here
this is thefile here
% cat there
this is thefile there
% cat here> there
% cat there
this is thefile here
Theoperator ">" simply takes the output from the cat command and
places isin the location specified after it.
Anothervital command to know is 'rm'. rm deletes a file from the
system, inthe same way DEL would on a DOS system. Not to much else to
say.
Critical inyour navigation of a Unix system is the ls command. ls is
DOS DIR onheroin. Simply type ls and you get a nice, neat list of
files in thedirectory.
DIR oncontrolled substances:
There are afew command line parameters that you should know...
foremost isl. ls -l gets you a list of files, and valuable
informationabout each file, including permissions (more on that
later),size, and linked files.
Anotheruseful command for long file lists is C. ls -C gets you a
list offiles in multiple columns, much the same as DIR /W would
merit adouble column report of all existing files. A quick reminder:
ls -C isNOT the same as ls -c. Unix = case sensitive.
Another goodcommand to know, mv will move a file from directory to
directory. Forthose of you without DOS 6.0 <gasp>, mv simply copies a
file toanother directory and deletes the original.
quick tipfor files on the lam:
if you wantto rename a file (to protect the innocent), you need to
mv a fileto a different file name. A quick demo:
# ls
myfile
# catmyfile
this is myfile
# mv myfilemy_other_file
# ls
my_other_file
# catmy_other_file
this is myfile
Anothervastly important command is 'man'. In fact, man is probably
one of themost important commands extant for a beginning user... it
calls up thesystem's help files. To use man, simply type in 'man
command',where command is a Unix command you seek to gain
enlightenment regarding. It's a great way to gain an understanding of
Unixcommandline parameters.
If you areinterested in seeing who's been on of late, or just want a
few names totry to hack, type 'who'. You get a quick list of users
that haveaccessed the system lately. If you <god forbid> need to know
who you areat this point, type 'whoami'.
If you wantto change your identity on the system, type 'su name'
where nameis an account on the system. It'll ask you for the account
password,then, *presto*... instant transmogrification.
A Caveatfor smart alec hackers:
Unixtypically logs usage of the su command. While su may seem like a
greatopportunity to try to hack out passwords manually without
worryingabout the system hanging up after 3 attempts, it's typically
not a goodidea to do this, as it may alert the administrators to
yourpresence.
*Numero Unoon the list of commands NEVER to use on a Unix system:
The 'passwd'command changes your password on a Unix system. Seems
innocousenough, eh? Uh-uh. If your account is active, and there's a
very strongchance that it either is or will be, there is no better
way to losethe account than to change the password, only to have the
legitimateuser alert the sysadmins when he/she can't gain access to
his/hernormal account (well, there are better ways... you could
simply mailthe sysadmin and tell him you are trying to hack his
grandmother's life support machine through your account).
I've seenthis single, quick command turn a extremely lax system
into anironclad security compound in less than a day.
DONT-FUCK-WITH-IT.
*Numero Doson that same list:
The 'mail'command reads and sends mail. So what? Well, unless your
account isstable (and it isn't unless you either paid for it or
killed theoriginal owner in such a way that his body cannot claw it's
way out ofit's grave to it's keyboard), the user is more likely than
not going toknow if you read his mail. In addition, if you send mail
out of thesystem (type 'mail', and a username/address; type in your
message andend it with a ^d on it's own line), the response from your
message willlikewise alert the user to your presence.
SystemSpelunking
-----------------
The firstplace you want to check out in the wild uncharted directory
tree of yourfriendly neighborhood Unix system is the "/etc"
directory. What'sin it? The single most intensely important file on
the system (besidesa world writable root owned SUID file... but don't
worry aboutthat)... the passwd file.
What is inthe passwd file?
ю a list of all accounts on the system
ю a list of the passwords for these accounts
ю a list of access levels for these accounts
ю a list of the home directories for theseaccounts
ю a list of information pertaining to theseaccounts.
Why the hellthe Unix designers decided this file should be world
readable isbeyond me. Be content to know that your standard everyday
run-of-the-mill-lacking-in-certified-cosmic-power'cat' command WILL
display thisfile. As will pg and more. However, because most users
don't havewrite permissions (more on that later) to the /etc
directory,'cat' is pretty much the only applicable command here.
However, ifyou need to copy the file to your own directory (for
whateverreason), just cat it there with the directional operator (>).
The catch:
Well, thereare two catches here. First off, regardless of system
security, ifthe passwords are in the file, they are encrypted. You
can't decryptthem. Although you can get a list of accounts without
passwordsthis way (just look for accounts with no entry in the
passwordfield), and a list of accounts that can't be logged onto
remotely/atall (NO LOGIN), you can't get much else. Sucks, don't it?
Notice Isaid 'if' the passwords are there.
<ominoussoundtrack please>
Somehorrible, paranoid, draconian system administrators mutilate
their passwdfiles in such a way that (*gasp*) the passwords don't
show up. Allyou get is one cold, icy X staring at you from the bowels
of UnixShell Siberia, mocking you as you pull your hair out in
frustration (sorry,but this is a sore spot with me). The kidnapped
passwordsreside in the shadow file in the /etc directory, available
with yourstandard everyday run-of-the-mill-but-distinct-in-the-fact-
that-only-root-level-accounts-can-use-it-to-this-extent'cat' command.
Well, if thepasswords are encrypted, what good are they?
Bythemselves, nothing. A account with a Unix encrypted password will
get you nofurther than an account with no listed password at all. You
can't evendeduce the amount of characters in the password if it's
encrypted. Sowhat's the use?
The Unixmethod of encrypting files is available to the public. It is
also, tomost mortals, irreversable. Essentially, this means you can
encrypt astring of characters, but not decrypt it. Even the unix
systemitself doesn't decrypt the password when you log on...
When you logon, the Unix system takes whatever you enter at the
passwordprompt, encrypts it, and matches it to the entry in the
passwd file.Thus, the Unix system never decrypts the password... it
onlycompares it to a different encrypted string.
While thismay not sound too particularly useful at first, it is.
There areprograms that have been written to do the same thing on a
personalcomputer... you supply it a list of passwords and a list of
words toattempt to use as passwords (called dictionaries), and it
spends thenight encrypting dictionaries and matching them to password
entries. Byrunning a dictionary through a passwd file, on a typical
system, youcan usually get 10-20 accounts. Good personal computer
examples ofthis program idea include Killer Cracker (the industry
standard, soto speak) and CrackerJack (faster than Killer Cracker).
Quick tipsfor CrackerJunkies with leech access at an H/P BBS:
A standarddictionary will not uncover passwords protected with an
appendeddigit or non-alphanumeric character. In order to get around
this, youneed only grab a program that processes the dictionary file
to add thatdigit to each entry in the dictionary... although this
takeslonger, and you'll need to do it multiple times, you can
typicallyget 10 more accounts just by adding a 1 to every entry.
Files anddirectories in Unix are characterized further by their
permissions.Permissions are a standard system of who gets access to a
specificfunction of that file or directory. Standard permissions
includeread, write, and execute. You can get a list of permissions by
typing 'ls -l'.The first field in the listing contains the
permissions,grouped as follows:
owner group world
--------------------
rwx rwx rwx
(Not drawnto scale... in fact, it doesn't look anything like that).
Essentially,as long as the letter is there, you have access to that
facet of thefile. If the letter is not there, you'll see a dash...
meaning youdon't have access to that function. An example:
rwxr-x--x
In thiscase, the owner of the file can Read the file, Write to the
file, andeXecute the file; members of his group (a bunch of linked
accounts) canRead the file, CANNOT Write to the file, and can eXecute
the file;and the rest of the user population CANNOT Read or Write to
the file,but CAN eXecute the file.
rwx---rwx
is a WORLD-READABLE,WORLD-WRITABLE, WORLD-EXECUTABLE file. This
simply meansthat anyone can read, write, or execute the file.
Anotherpermission sometimes set to a file is the SUID bit. An SUID
filecontains a smallcase s in the user executable section of the
permissionslist...
rws--x--x
When youexecute an SUID file, your user ID becomes that of the owner
of the file.While this may not look to important at first, by now you
should knowthat no really important super elite hacker concept does.
Take a lookat this:
rwsr-x--x
Synopsis?It's a world executable SUID file. In essence, anyone can
execute thefile, and in doing so, become the owner of the file for
the durationof the time that file is operating. However, this doesn't
get youmuch, because you typically can't do anything while the
programisrunning. More likely than not, it's calculating how many
pencils itneeds to order for school tomorrow or some other such
drivel.
The realpower of the SUID file comes into play in this situation:
rwsrwxrwx
You won'tsee a lot of these, but when you do, look out. What you have
here is aworld writable SUID file... and a world writable program can
be anyprogram on the system you have read access to. Like, say,
/bin/sh... theUnix shell...
Quickcommand line example... 'diablo' is a root owned, world writable
SUID file. I'mgoing to ignore the rest of the output of the ls
command.
#ls -l
rwsrwxrwx......diablo
#cat /bin/sh> diablo
#diablo
$
Oh, just soyou know, the $ prompt denotes root access.
Good deal,huh? In general, if you have right privs to an SUID file,
copy it toyour own directory and cat /bin/sh into it. You now have an
instantgateway to the account of the owner of that file.
If you wantto find files that you can do this with, try this out:
#find / -userroot -perm -4000 -exec /bin/ls -al {} ";"
This willgive you a list of all root owned SUID files. If you want
more info onthe 'find' command, just 'man find'.
Well, I'moverdo for an appointment on the IRC in #warez... so I'll
cut off here.I hope I've been of assistance to you.
----------------------------------------------------------------------------
A C T U AL A R T I C L E E N D S H E R E . . .
Please feelfree to save an extra 1k of file space and invoke the DOS
EDIT CUTcommand at the dotted line. Do not remove the rest of this
article onpenalty of law.
S00P3R GR00P-3SQU3GR33TZ / +HANX
Greets goout to Nowhere Man, INC, THG, UNT, SaD, SoD, PTA, SOB
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