CEHv6 Module 04 Google Hacking pdf pdf

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Ethical Hacking and

Counterm easures

Version 6

M o d u le IV

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Module Objective

This m odule will fam iliarize you with:

• What is Google Hacking

• What a Hacker Can Do With Vulnerable Site

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• Google Hacking Basics

• Google Advanced Operators

• Pre-Assessm ent

• Locating Exploits and Finding Targets

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• Tracking Down Web Servers, Login Portals, and Network

Hardware

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Module Flow

Google Hacking Pre-Assessm ent

What a Hacker Can Do

With Vulnerable Site Locating Exploits and Finding Targets

Google Hacking Basics Tracking Down Web Servers,

Login Portals, and Network Hardware

Google Advanced Operators Google Hacking Tools

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What is Google Hacking

Google hacking is a term that refers to the art of creating

com plex search engine queries in order to filter through large p g q g g am ounts of search results for inform ation related to com puter security

In its m alicious form at it can be used to detect websites that In its m alicious form at, it can be used to detect websites that are vulnerable to num erous exploits and vulnerabilities as well as locate private, sensitive inform ation about others, such as credit card num bers, social security num bers, and passwords

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What a Hacker Can Do With

Vulnerable Site

Inform ation that the Google Hacking Database identifies:

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Advisories and server vulnerabilities

Error m essages that contain too m uch inform ation

Files containing passwords

Sensitive directories

Pages containing logon portals

Pages containing network or vulnerability data such as firewall

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Anonym ity with Caches

Hackers can get a copy sensitive data even if plug on that pesky Web server is pulled off and they can crawl into entire website without even sending a single packet to server

they can crawl into entire website without even sending a single packet to server

If the web server does not get so m uch as a packet, it can not write any thing to log files

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Using Google as a Proxy Server

Google som e tim es works as a proxy server which requires a Google translated URL and som e m inor URL m odification

translated URL and som e m inor URL m odification

Translation URL is generated through Google’s translation service located at www google com / translate t

service, located at www.google.com / translate_ t

If URL is entered in to “Translate a web page” field, by selecting a language pair and clicking on Translate button Google will

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Directory Listings

A directory listing is a type of Web page that lists files and directories that exist on a Web server

server

It is designed such that it is to be navigated by clicking directory links, directory listings typically have a title that describes the current directory, a list of files and directories that can be clicked

J ust like an FTP server, directory listings offer a no-frills, easy-install solution for granting access to files that can be stored in categorized folders

access to files that can be stored in categorized folders

Problem s faced by directory listings are:

• They do not prevent users from downloading certain files or accessing certain directories hence they are not secure • They can display inform ation that helps an attacker learn specific technical details about Web server

• They do not discrim inate between files that are m eant to be public and those that are m eant to rem ain behind the

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scenes

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Locating Directory Listings

Since directory listings offer parent directory links and allow y g p y browsing through files and folders, attacker can find sensitive data sim ply by locating listings and browsing through them

Locating directory listings with Google is fairly straightforward as they begin with phrase “Index of,” which shows in tittle

An obvious query to find this type of page m ight be

ntitle:index.of, which can find pages with the term “index of” in the title of the docum ent

intitle:index.of “parent directory ” or intitle:index.of “nam e size” queries indeed provide directory listings by not only f d f l b k d f f d d

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Locating Directory Listings

(cont’d)

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Finding Specific Directories

This is easily accom plished by adding the nam e of the directory to the search

query

To locate “adm in” directories that are To locate adm in directories that are

accessible from directory listings, queries such as intitle:index.of.adm in or

intitle:index.of inurl:adm in will work well, as shown in the following figure

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Finding Specific Files

As the directory listing is in tree style, it is also possible to find specific files in a

directory listing

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Server Versioning

The inform ation an attacker can use to determ ine the best m ethod for attacking a Web server is the exact software version

Web server is the exact software version

An attacker can retrieve that inform ation by connecting directly to the Web port of that server and issuing a request for the HTTP headers

Som e typical directory listings provide the nam e of the server software as well as the version num ber at the bottom portion. These inform ation are faked and attack can be done on web server

intitle:index.of “ server at” query will locate all directory listings on the Web with

index of in the title and server at any w here in the text of the page

In addition to identifying the Web server version, it is also possible to determ ine the operating system of the server as well as m odules and other software that is installed

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Going Out on a Lim b: Traversal

Techniques

Attackers use traversal techniques to expand a sm all foothold into a larger

com prom ise

co p o

se

The query intitle:index.of inurl:“/ adm in/ *” is helped to traversal as

shown in the figure:

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Directory Traversal

By clicking on the parent directory link the sub links under y g p y it will open. This is basic directory traversal

Regardless of walking through the directory tree ,

traversing outside the Google search wandering around on traversing outside the Google search wandering around on the target Web server is also be done

Th d i th URL ill b h d ith th d The word in the URL will be changed with other words

Poorly coded third-party software product installed in the

t di t t hi h ll

server accepts directory nam es as argum ents which allows users to view files above the web server directory

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Increm ental Substitution

This technique involves replacing num bers in a URL in an attem pt to

find directories or files that are hidden, or unlinked from other pages

By changing the num bers in the file nam es, the other files can be found

In som e exam ples, substitution is used to m odify the num bers in the

URL to locate other files or directories that exist on the site

• / docs/ bulletin/ 2.xls could be m odified to / docs/ bulletin/ 2.xls

• / DigLib_ thum bnail/ spm g/ hel/ 0 0 0 1/ H/ could be changed to

/ Di Lib th

b

il/

/ h l/

/ H/

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/ DigLib_ thum bnail/ spm g/ hel/ 0 0 0 2/ H/

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Extension Walking

File extensions and how filetype operator can be used to locate files with specific file i

extensions

HTM files can be easily searched with a query such as filetype:HTM HTM

Filetype searches require a search param eter and files ending in HTM always have HTM in the URL

After locating HTM files, substitution technique is used to find files with the sam e file nam e and different extension

E i d i f b k fil i l di li i

Easiest way to determ ine nam es of backup files on a server is to locate a directory listing using intitle:index.of or to search for specific files with queries such as intitle:index.of index.php.bak or inurl:index.php.bak

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Google Advanced Operators

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Site Operator

The site operator is absolutely invaluable during the p y g inform ation-gathering phase of an assessm ent

Site search can be used to gather inform ation about the servers g and hosts that a target hosts

Using sim ple reduction techniques, you can quickly get an idea Using sim ple reduction techniques, you can quickly get an idea about a target’s online presence

Consider the sim ple exam ple of site:washingtonpost.com – Consider the sim ple exam ple of site:washingtonpost.com site:www.washingtonpost.com

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Site Operator (cont’d)

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intitle:index.of

intitle:index.of is the universal search for

directory listings

In m ost cases, this search applies only

to Apache-based servers, but due to the

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Screenshot

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error | warning

Error m essages can reveal a great deal of inform ation about a target

Oft l k d id i i ht i t th li ti Often overlooked, error m essages can provide insight into the application or operating system software a target is running, the architecture of the network the target is on, inform ation about users on the system , and m uch m ore

Not only are error m essages inform ative, they are prolific

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error | warning (cont’d)

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login | logon

Login portals can reveal the software and operating system of a target, and in m any cases “self-help” docum entation is linked from the m ain and in m any cases self help docum entation is linked from the m ain page of a login portal

These docum ents are designed to assist users who run into problem s g p during the login process

Whether the user has forgotten his or her password or even usernam e, Whether the user has forgotten his or her password or even usernam e, this docum ent can provide clues that m ight help an attacker

Docum entation linked from login portals lists e-m ail addresses, phone

b f h i h h l bl d

num bers, or URLs of hum an assistants who can help a troubled user regain lost access

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login | logon (cont’d)

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usernam e | userid | em ployee.ID |

“your usernam e is”

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password | passcode | “your

password is”

p

The word password is so com m on on the Internet, there are over The word password is so com m on on the Internet, there are over 73 m illion results for this one-word query

During an assessm ent, it is very likely that results for this query com bined with a site operator will include pages that provide help to users who have forgotten their passwords

In som e cases, this query will locate pages that provide policy inform ation about the creation of a password

This type of inform ation can be used in an intelligent-guessing or

b t f i i t d fi ld

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password | passcode | “your

password is” (cont’d)

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adm in | adm inistrator

The word adm inistrator is often used to describe the person in control of a k

network or system

The word adm inistrator can also be used to locate adm inistrative login pages, or login portals

The phrase Contact your system adm inistrator is a fairly com m on phrase on p y y y p the Web, as are several basic derivations

A query such as “please contact your * adm inistrator” will return results that

f l l it d t t t t k d t b

reference local, com pany, site, departm ent, server, system , network, database, e-m ail, and even tennis adm inistrators

If a Web user is said to contact an adm inistrator, chances are that the data

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adm in login

adm in login Reveals Adm inistrative Login Pages

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– ext:htm l – ext:htm

– ext:shtm l – ext:asp – ext:php

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p p

The – ext:htm l – ext:htm – ext:shtm l – ext:asp –

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fil

ext:php

query uses ext, a synonym for the filetype

operator, and is a negative query

It returns no results when used alone and should

be com bined with a site operator to work properly

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– ext:htm l – ext:htm – ext:shtm l –

ext:asp – ext:php (cont’d)

ext:asp ext:php (cont d)

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inurl:tem p | inurl:tm p |

inurl:backup | inurl:bak

p |

The inurl:tem p | inurl:tm p | inurl:backup | inurl:bak query , com bined

ith th it

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fil

w ith the site operator, searches for tem porary or backup files or

directories on a server

Although there are m any possible nam ing conventions for tem porary or

backup files, this search focuses on the m ost com m on term s

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Pre-Assessm ent

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intranet | help.desk

The term intranet, despite m ore specific technical m eanings, has becom e a generic term that describes a network confined to a sm all group

In m ost cases, the term intranet describes a closed or private network unavailable to the general public

Many sites have configured portals that allow access to an y g p intranet from the Internet, bringing this typically closed network one step closer to the potential attackers

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Locating Exploits and

g

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Finding Targets

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Locating Public Exploit Sites

One way to locate exploit code is to focus on the file extension of the source code and then search for specific content within that code

search for specific content within that code

Since source code is the text-based representation of the difficult-to-read m achine code, Google is well suited for this task

For exam ple, a large num ber of exploits are written in C, which generally use source code ending in a .c extension

A f fil t l it t d lt t f hi h tl th A query for filety pe:c exploit returns around 5,0 0 0 results, m ost of w hich are exactly the types of program s you are looking for

These are the m ost popular sites hosting C source code containing the word exploit, the

t d li t i d t t f li t f b k k returned list is a good start for a list of bookm arks

Using page-scraping techniques, you can isolate these sites by running a UNIX com m and against the dum ped Google results page

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Locating Exploits Via Com m on

Code Strings

g

Another way to locate exploit code is to focus on com m on strings within

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the source code itself

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d fil

One way to do this is to focus on com m on inclusions or header file

references

For exam ple, m any C program s include the standard input/ output library

functions, which are referenced by an include statem ent such as # include

<stdio.h> within the source code

A query like this would locate C source code that contained the word

exploit, regardless of the file’s extension:

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Locating Source Code with

Com m on Strings

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Locating Vulnerable Targets

Attackers are increasingly using

Google to locate Web-based

In fact, it’s not uncom m on for

public vulnerability

i

Google to locate Web based

targets vulnerable to specific

exploits

announcem ents to contain

Google links to potentially

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Locating Targets Via Dem onstration

Pages

Develop a query string to locate vulnerable targets on the Web; the vendor’s Web

site is a good place to discover what exactly the product’s Web pages look like

site is a good place to discover what exactly the product s Web pages look like

For exam ple, som e adm inistrators m ight m odify the form at of a vendor-supplied

Web page to fit the them e of the site

These types of m odifications can im pact the effectiveness of a Google search that

targets a vendor-supplied page form at

You can find that m ost sites look very sim ilar and that nearly every site has a

“powered by” m essage at the bottom of the m ain page

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“

Powered by” Tags Are Com m on Query

Fodder for Finding Web Applications

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Locating Targets Via Source Code

A hacker m ight use the source code of a program to discover ways to

g

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g

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search for that software with Google

To find the best search string to locate potentially vulnerable targets, you

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p

y

g

, y

can visit the Web page of the software vendor to find the source code of

the offending software

In cases where source code is not available an attacker m ight opt to

In cases where source code is not available, an attacker m ight opt to

sim ply download the offending software and run it on a m achine he

controls to get ideas for potential searches

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Vulnerable Web Application

Exam ples (cont’d)

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Locating Targets Via CGI Scanning

One of the oldest and m ost fam iliar techniques for locating vulnerable Web servers is through the use of a CGI scanner

These program s parse a list of known “bad” or vulnerable Web files and attem pt to locate those files on a Web server

Based on various response codes, the scanner could detect the presence of these potentially l bl f l

vulnerable files

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A Single CGI Scan-Style Query

Exam ple: search for inurl:/ cgi-bin/ userreg.cgi

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Tracking Down Web

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Servers, Login Portals, and

Network Hardware

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Finding IIS 5.0 Servers

Query for

“Microsoft-IIS/ 5.0 server at”

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Web Server Software Error

Messages

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Error m essages contain a lot of useful inform ation, but in the context of locating specific servers, you can use portions of various error m essages to locate servers running specific

f i

software versions

The best way to find error m essages is to figure out what m essages the server is capable of generating

You could gather these m essages by exam ining the server source code or configuration files or by actually generating the errors on the server yourself

The best way to get this inform ation from IIS is by exam ining the source code of the error pages them selves

IIS 5 and 6, by default, display static HTTP/ 1.1 error m essages when the server encounters som e sort of problem

Th d b d f l i h %SYSTEMROOT%\ h l \ ii H l \

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Web Server Software Error Messages

(cont’d)

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A query such as intitle:”The page cannot be found” “please follow ing”

“Internet Services” can be used to search for IIS servers that present a*

p

40 0 error

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IIS HTTP/ 1.1 Error Page Titles

(cont’d)

(cont d)

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“Object Not Found” Error Message

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Apache Web Server

Apache Web servers can also be located by focusing on server-generated error

m essages

Som e generic searches such as

“Apache/ 1.3.27 Server at” -intitle:index.of

intitle:inf” or “Apache/ 1.3.27 Server at” -intitle:index.of intitle:error

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Application Software Error

Messages

Although this ASP m essage is fairly benign som e ASP

Although this ASP m essage is fairly benign , som e ASP

error m essages are m uch m ore revealing

Consider the query

“ASP.N ET_ SessionId”“data source=”,

which locates unique strings found in ASP.NET

application state dum ps

These dum ps reveal all sorts of inform ation about the

running application and the Web server that hosts that

application

Er r o r

app cat o

An advanced attacker can use encrypted password data

and variable inform ation in these stack traces to subvert

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ASP Dum ps Provide Dangerous

Details

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Many Errors Reveal Pathnam es

and Filenam es

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Default Pages

Another way to locate specific types of servers or Web ft i t h f d f lt W b

software is to search for default Web pages

Most Web software, including the Web server software itself, ships with one or m ore default or test pages

These pages can m ake it easy for a site adm inistrator to These pages can m ake it easy for a site adm inistrator to test the installation of a Web server or application

Google crawls a Web server while it is in its earliest stages Google crawls a Web server while it is in its earliest stages of installation, still displaying a set of default pages

In these cases there is generally a short window of tim e

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Locating Default Installations of IIS 4.0 on

Windows NT 4.0 / OP

/

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Default Pages Query for Web Server

Many different types of Web server can be located by querying for

default pages as well

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Outlook Web Access Default Portal

Query

allinurl:”exchange/ logon.asp”

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Searching for Passwords

Password data, one of the

“Holy Grails” during a

penetration test, should be

protected

p

Unfortunately, m any

exam ples of Google queries

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Windows Registry Entries Can Reveal

Passwords

Query like

filety pe:reg intext: “internet account m anager”

could

reveal interesting keys containing password data

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Usernam es, Cleartext Passwords, and

Hostnam es!

Search for password inform ation

intext:(passw ord |

Search for password inform ation,

intext:(passw ord |

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Google Hacking Tools

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Google Hacking Database

(GHDB)

The Google Hacking Database (GHDB) contains queries that identify

sensitive data such as portal logon pages, logs with network security

Visit http:/ / johnny.ihackstuff.com

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inform ation, and so on

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Google Hacking Database

(GHDB)

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