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Hands-On Ethical Hacking and Network Defense

Hands-On Ethical Hacking and Network Defense. Chapter 10 Hacking Web Servers. Objectives. Describe Web applications Explain Web application vulnerabilities Describe the tools used to attack Web servers. Understanding Web Applications. It is nearly impossible to write a program without bugs

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Hands-On Ethical Hacking and Network Defense

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  1. Hands-On Ethical Hacking and Network Defense Chapter 10 Hacking Web Servers

  2. Objectives • Describe Web applications • Explain Web application vulnerabilities • Describe the tools used to attack Web servers Hands-On Ethical Hacking and Network Defense

  3. Understanding Web Applications • It is nearly impossible to write a program without bugs • Some bugs create security vulnerabilities • Web applications also have bugs • Web applications have a larger user base than standalone applications • Bugs are a bigger problem for Web applications Hands-On Ethical Hacking and Network Defense

  4. Web Application Components • Static Web pages • Created using HTML • Dynamic Web pages • Need special components • <form> tags • Common Gateway Interface (CGI) • Active Server Pages (ASP) • PHP • ColdFusion • Scripting languages • Database connectors Hands-On Ethical Hacking and Network Defense

  5. Web Forms • Use the <form> element or tag in an HTML document • Allows customer to submit information to the Web server • Web servers process information from a Web form by using a Web application • Easy way for attackers to intercept data that users submit to a Web server Hands-On Ethical Hacking and Network Defense

  6. Web Forms (continued) • Web form example <html> <body> <form> Enter your username: <input type="text" name="username"> <br> Enter your password: <input type="text" name="password"> </form></body></html> Hands-On Ethical Hacking and Network Defense

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  8. Common Gateway Interface (CGI) • Handles moving data from a Web server to a Web browser • The majority of dynamic Web pages are created with CGI and scripting languages • Describes how a Web server passes data to a Web browser • Relies on Perl or another scripting language to create dynamic Web pages • CGI programs can be written in different programming and scripting languages Hands-On Ethical Hacking and Network Defense

  9. Common Gateway Interface (CGI) (continued) • CGI example • Written in Perl • Hello.pl • Should be placed in the cgi-bin directory on the Web server #!/usr/bin/perl print "Content-type: text/html\n\n"; print "Hello Security Testers!"; Hands-On Ethical Hacking and Network Defense

  10. Active Server Pages (ASP) • With ASP, developers can display HTML documents to users on the fly • Main difference from pure HTML pages • When a user requests a Web page, one is created at that time • ASP uses scripting languages such as JScript or VBScript • Not all Web servers support ASP Hands-On Ethical Hacking and Network Defense

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  12. Active Server Pages (ASP) (continued) • ASP example <HTML> <HEAD><TITLE> My First ASP Web Page </TITLE></HEAD> <BODY> <H1>Hello, security professionals</H1> The time is <% = Time %>. </BODY> </HTML> • Microsoft does not want users to be able to view an ASP Web page’s source code • This can create serious security problems Hands-On Ethical Hacking and Network Defense

  13. Apache Web Server • Tomcat Apache is another Web Server program • Tomcat Apache hosts anywhere from 50% to 60% of all Web sites • Advantages • Works on just about any *NIX and Windows platform • It is free • Requires Java 2 Standard Runtime Environment (J2SE, version 5.0) Hands-On Ethical Hacking and Network Defense

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  16. Using Scripting Languages • Dynamic Web pages can be developed using scripting languages • VBScript • JavaScript • PHP Hands-On Ethical Hacking and Network Defense

  17. PHP: Hypertext Processor (PHP) • Enables Web developers to create dynamic Web pages • Similar to ASP • Open-source server-side scripting language • Can be embedded in an HTML Web page using PHP tags <?php and ?> • Users cannot see PHP code on their Web browser • Used primarily on UNIX systems • Also supported on Macintosh and Microsoft platforms Hands-On Ethical Hacking and Network Defense

  18. PHP: Hypertext Processor (PHP) (continued) • PHP example <html> <head> <title>My First PHP Program </title> </head> <body> <?php echo '<h1>Hello, Security Testers!</h1>'; ?> </body> </html> • As a security tester you should look for PHP vulnerabilities Hands-On Ethical Hacking and Network Defense

  19. ColdFusion • Server-side scripting language used to develop dynamic Web pages • Created by the Allaire Corporation • Uses its own proprietary tags written in ColdFusion Markup Language (CFML) • CFML Web applications can contain other technologies, such as HTML or JavaScript Hands-On Ethical Hacking and Network Defense

  20. ColdFusion (continued) • CFML example <html> <head> <title>Using CFML</title> </head> <body> <CFLOCATION URL="www.isecom.org/cf/index.htm" ADDTOKEN="NO"> </body> </html> • CFML is not exempt of vulnerabilities Hands-On Ethical Hacking and Network Defense

  21. VBScript • Visual Basic Script is a scripting language developed by Microsoft • Converts static Web pages into dynamic Web pages • Takes advantage of the power of a full programming language • VBScript is also prone to security vulnerabilities • Check the Microsoft Security Bulletin for information about VBScript vulnerabilities Hands-On Ethical Hacking and Network Defense

  22. VBScript (continued) • VBScript example <html> <body> <script type="text/vbscript"> document.write("<h1>Hello Security Testers!</h1>") document.write("Date Activated: " & date()) </script> </body> </html> Hands-On Ethical Hacking and Network Defense

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  24. JavaScript • Popular scripting language • JavaScript also has the power of a programming language • Branching • Looping • Testing • Variety of vulnerabilities exist for JavaScript that have been exploited in older Web browsers Hands-On Ethical Hacking and Network Defense

  25. JavaScript (continued) • JavaScript example <html> <head> <script type="text/javascript"> function chastise_user() { alert("So, you like breaking rules?") document.getElementByld("cmdButton").focus() } </script> </head> <body> <h3>"If you are a Security Tester, please do not click the command button below!"</h3> <form> <input type="button" value="Don't Click!" name="cmdButton" onClick="chastise_user()" /> </form> </body> </html> Hands-On Ethical Hacking and Network Defense

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  28. Connecting to Databases • Web pages can display information stored on databases • There are several technologies used to connect databases with Web applications • Technology depends on the OS used • ODBC • OLE DB • ADO • Theory is the same Hands-On Ethical Hacking and Network Defense

  29. Open Database Connectivity (ODBC) • Standard database access method developed by the SQL Access Group • ODBC interface allows an application to access • Data stored in a database management system • Any system that understands and can issue ODBC commands • Interoperability among back-end DBMS is a key feature of the ODBC interface Hands-On Ethical Hacking and Network Defense

  30. Open Database Connectivity (ODBC) (continued) • ODBC defines • Standardized representation of data types • A library of ODBC functions • Standard methods of connecting to and logging on to a DBMS Hands-On Ethical Hacking and Network Defense

  31. Object Linking and Embedding Database (OLE DB) • OLE DB is a set of interfaces • Enables applications to access data stored in a DBMS • Developed by Microsoft • Designed to be faster, more efficient, and more stable than ODBC • OLE DB relies on connection strings • Different providers can be used with OLE DB depending on the DBMS to which you want to connect Hands-On Ethical Hacking and Network Defense

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  33. ActiveX Data Objects (ADO) • ActiveX defines a set of technologies that allow desktop applications to interact with the Web • ADO is a programming interface that allows Web applications to access databases • Steps for accessing a database from a Web page • Create an ADO connection • Open the database connection you just created • Create an ADO recordset • Open the recordset • Select the data you need • Close the recordset and the connection Hands-On Ethical Hacking and Network Defense

  34. Understanding Web Application Vulnerabilities • Many platforms and programming languages can be used to design a Web site • Application security is as important as network security • Attackers controlling a Web server can • Deface the Web site • Destroy or steal company’s data • Gain control of user accounts • Perform secondary attacks from the Web site • Gain root access to other applications or servers Hands-On Ethical Hacking and Network Defense

  35. Application Vulnerabilities Countermeasures • Open Web Application Security Project (OWASP) • Open, not-for-profit organization dedicated to finding and fighting vulnerabilities in Web applications • Publishes the Ten Most Critical Web Application Security Vulnerabilities • Top-10 Web application vulnerabilities • Unvalidated parameters • HTTP requests are not validated by the Web server • Broken access control • Developers implement access controls but fail to test them properly Hands-On Ethical Hacking and Network Defense

  36. Application Vulnerabilities Countermeasures (continued) • Top-10 Web application vulnerabilities (continued) • Broken account and session management • Enables attackers to compromise passwords or session cookies to gain access to accounts • Cross-site scripting (XSS) flaws • Attacker can use a Web application to run a script on the Web browser of the system he or she is attacking • Buffer overflows • It is possible for an attacker to use C or C++ code that includes a buffer overflow Hands-On Ethical Hacking and Network Defense

  37. Application Vulnerabilities Countermeasures (continued) • Top-10 Web application vulnerabilities (continued) • Command injection flaws • An attacker can embed malicious code and run a program on the database server • Error-handling problems • Error information sent to the user might reveal information that an attacker can use • Insecure use of cryptography • Storing keys, certificates, and passwords on a Web server can be dangerous Hands-On Ethical Hacking and Network Defense

  38. Application Vulnerabilities Countermeasures (continued) • Top-10 Web application vulnerabilities (continued) • Remote administration flaws • Attacker can gain access to the Web server through the remote administration interface • Web and application server misconfiguration • Any Web server software out of the box is usually vulnerable to attack • Default accounts and passwords • Overly informative error messages Hands-On Ethical Hacking and Network Defense

  39. Application Vulnerabilities Countermeasures (continued) • WebGoat project • Helps security testers learn how to perform vulnerabilities testing on Web applications • Developed by OWASP • WebGoat can be used to • Reveal HTML or Java code and any cookies or parameters used • Hack a logon name and password Hands-On Ethical Hacking and Network Defense

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  42. Application Vulnerabilities Countermeasures (continued) • WebGoat can be used to • Traverse a file system on a Windows XP computer running Apache • WebGoat’s big challenge • Defeat an authentication mechanism • Steal credit cards from a database • Deface a Web site Hands-On Ethical Hacking and Network Defense

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  46. Assessing Web Applications • Security testers should look for answers to some important questions • Does the Web application use dynamic Web pages? • Does the Web application connect to a backend database server? • Does the Web application require authentication of the user? • On what platform was the Web application developed? Hands-On Ethical Hacking and Network Defense

  47. Does the Web Application Use Dynamic Web Pages? • Static Web pages do not create a security environment • IIS attack example • Submitting a specially formatted URL to the attacked Web server • IIS does not correctly parse the URL information • Attackers could launch a Unicode exploit http://www.nopatchiss.com/scripts/..%255c..%255cwinnt/system32/cmd.exe?/c+dir+c • Attacker can even install a Trojan program Hands-On Ethical Hacking and Network Defense

  48. Does the Web Application Connect to a Backend Database Server? • Security testers should check for the possibility of SQL injection being used to attack the system • SQL injection involves the attacker supplying SQL commands on a Web application field • SQL injection examples SELECT * FROM customer WHERE tblusername = ' ' OR 1=1 -- ' AND tblpassword = ' ' or SELECT * FROM customer WHERE tblusername = ' OR "=" AND tblpassword = ' OR "=" Hands-On Ethical Hacking and Network Defense

  49. Does the Web Application Connect to a Backend Database Server? (continued) • Basic testing should look for • Whether you can enter text with punctuation marks • Whether you can enter a single quotation mark followed by any SQL keywords • Whether you can get any sort of database error when attempting to inject SQL Hands-On Ethical Hacking and Network Defense

  50. Does the Web Application Require Authentication of the User? • Many Web applications require another server authenticate users • Examine how information is passed between the two servers • Encrypted channels • Verify that logon and password information is stored on secure places • Authentication servers introduce a second target Hands-On Ethical Hacking and Network Defense

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