OWASP Top 10 And Insecure Software Root Causes

Web Application Vulnerabilities and Insecure Software Root Causes: The OWASP Top 10 Cincinnati Chapter Meeting February 26 th , 2008 Marco Morana

Agenda Application Security and The Medical Metaphor Software Security From a Process Perspective Software Security Strategy Essential Elements For Secure Coding Standards/Guidelines OWASP Top Ten 2007 Security Issues, Threats, Software Root Causes, Validations and Recommendations Appendix

Application Security and The Medical Metaphor Three dimensions of the application security problem Symptoms Risk factors Root causes The symptoms are the clues that lead to the diagnosis: potential vulnerabilities and exploits The root causes: security design flaws, security bugs (coding errors), insecure-configuration The risk factors: how much damage can be done, how easy is to reproduce the exploits, how many users are exposed and how easy is to discover the vulnerabilities

Focus on the root cause: Insecure software.. … and still keep a 360 degree perspective: People, Process and Tools

Process perspective: Build Security in the SDLC

Software Security Strategy “ If your software security practices are not yet mature be pragmatic and start making secure coding a responsibility for who builds software in your organization

Essential Elements For Secure Coding Standards/Guidelines Describe secure coding requirement in terms of: The common security issues (e.g. OWASP T10) The issue type (e.g. Application Security Frame) The security threat or how can be exploited The in-secure code root cause of the vulnerability The “How to” find the vulnerability with black box and white box testing The secure coding requirement/recommendation The risk rating (e.g. STRIDE/DREAD, OWASP)

Common Security Issues: The OWASP Top 10 The Ten Most Critical Aimed to educate developers, architects and security practitioners about the consequences of the most common web application security vulnerabilities Living document: 2007 T10 different from 2004 T10 Not a silver bullet for software security A great start, but not a standard

Common Security Issues: OWASP Top 10 2007 Cross Site Scripting (XSS) Injection Flaws Insecure Remote File Include Insecure Direct Object Reference Cross Site Request Forgery (CSRF) Information Leakage and Improper Error Handling Broken Authentication and Session Management Insecure Cryptographic Storage Insecure Communications Failure to Restrict URL Access http://www.owasp.org/index.php/Top_10

Common Security Issues: Top 10 Methodology Take the MITRE Vulnerability Trends for 2006 , and distill the Top 10 web application security issues

Common Security Issues: 2007 T10 vs. 2004 T10 29 10. Insecure Configuration Management 17 9. Denial of Service 4, 8, and 10 5. Buffer Overflows 7 1. Unvalidated Input 14 2. Broken Access Control (split in 2007 T10) 10. Failure to Restrict URL Access 8 Discussed under 10 9. Insecure Communications (NEW) 8 8. Insecure Storage 8. Insecure Cryptographic Storage 14 3. Broken Authentication and Session Management 7. Broken Auth. and Session Management 6 7. Improper Error Handling 6. Info Leakage and Improper Error Handling 36 5. Cross Site Request Forgery (CSRF) (NEW) 5 2. Broken Access Control (split in 2007 T10) 4. Insecure Direct Object Reference 3 3. Insecure Remote File Include (NEW) 2 6. Injection Flaws 2. Injection Flaws 1 4. Cross Site Scripting (XSS) 1. Cross Site Scripting (XSS) MITRE 2006 Raw Ranking OWASP Top 10 2004 OWASP Top 10 2007

Security Threats and OWASP T10 Vulnerabilities Phishing Exploit weak authorization, authorization, session management and input validation (XSS, XFS) vulnerabilities Privacy violations Exploit poor input validation, business rule and weak authorization, injection flaws, information leakage vulnerabilities Identity theft Exploit poor or non-existent cryptographic controls, malicious file execution, authentication, business rule and auth checks vulnerabilities

Security Threats and OWASP T10 Vulnerabilities (Cont) System compromise, data alteration or data destruction Exploit injection flaws, remote file inclusion-upload vulnerabilities Financial loss Exploit unauthorized transactions and CSRF attacks, broken authentication and session management, insecure object reference, weak authorization-forceful browsing vulnerabilities Reputation loss Depend on any evidence (not neccessarly exploitation) of a web application vulnerability

A1: Cross Site Scripting Issue A web site that gathers user input and reflects input back to the browser without filtering is vulnerable to cross-site scripting. Threats Attacker crafts a malicious URL providing user input that is really a script (Javascript, VBScript, etc.) sent via phishing or posted as a link on a malicious site. Script is sent to server as user input (query string, POST parameter, cookie, HTTP header, etc)

A1: Cross Site Scripting - Insecure Software Root Cause import java.io.*; import javax.servlet.http.*; import javax.servlet.*; public class HelloServlet extends HttpServlet { public void doGet (HttpServletRequest req, HttpServletResponse res) throws ServletException, IOException { String input = req.getHeader(“USERINPUT”); PrintWriter out = res.getWriter(); out.println(input); // echo User input. out.close(); } }

A1: Cross Site Scripting -How to find the potential vulnerability V erify whether an application or web server will respond to requests containing simple scripts with an HTTP response that are executed by the user’s browser. The attack vector can be a script to show sensitive information (e.g. cookie stored on the browser) in an alert http://server/cgi-bin/testcgi.exe?<SCRIPT>alert(“Cookie”+document.cookie)</SCRIPT>

A1: Cross Site Scripting -How to find the potential vulnerability

A1: Cross Site Scripting - Secure coding requirement Perform input data validation using white lists (e,g, default deny) of unsafe characters and output encoding. When using .NET make sure that request validation is enabled as well as HTML encoding for the content to be displayed. <pages validateRequest="true" ... /> Server.HtmlEncode(string) Enforce encoding in output to assure that the browser interprets any special characters as data and markup. HTML encoding usually means < becomes < , > becomes > , & becomes & , and " becomes &quot So for example the text <script> would be displayed as <script> but on viewing the markup it would be represented by <script>

A2: Injection Flaws Injection occurs when user-supplied data is sent to an interpreter as part of a command or query. Attackers trick the interpreter into executing unintended commands via supplying specially crafted data. Examples: SQL Injection, LDAP, XPath, XSLT, HTML, OS Command (e.g. CRLF) Injection and many more

A2: Injection Flaws –SQL Injection Issue Unfiltered input parameters alter the SQL query since the query is not parameterized (e.g. use of concatenated string instead of prepared statements, store procedures) Threat Malicious user construct an input containing malicious SQL query and supplies it in the input variable. The application passes the variable without filtering directly to the dynamically constructed SQL query or stored procedure. SQL malicious query executes on the sever.

A2: Injection Flaws –SQL Injection Attack Illustrated 3 Attacker sends data containing SQL fragments Attacker enters SQL fragments into a web page that uses input in a query 1 Attacker views unauthorized data Custom Code Accounts Finance Administration Transactions Communication Knowledge Mgmt E-Commerce Bus. Functions Database 2 Application sends modified query to database, which executes it

A2: Injection Flaws-SQL Injection - Insecure Software Root Cause public List getProductsByTitleKeyWords(String[] keywords) { JdbcTemplate jt = new JdbcTemplate(getDataSource()); String query = "select * from products where "+ createCriteria(keywords); List list = jt.query(query, new ProductRowMapper()); Iterator iter = list.iterator(); while (iter.hasNext()) { Product prod = (Product) iter.next(); prod.setFeedback(getFeedBacks(prod)); } return list; }

A2: Injection Flaws-SQL SQL Injection– How To Find The Potential Vulnerability Via Penetration Testing Using Attack Vectors ‘’ (double apostrophe), (single quote) , (comma) --‘ (comment) OR ‘1’=’1—‘ (always true statement) aaa’; DROP TABLE Docs;-- (use semicolon to break out the query) Via Source Code Analysis Looks for instances of dynamic queries constructions that use statement instead of Prepared statements

A2: Injection Flaws-SQL Injection - Secure coding requirements Use SQL Parameterized Queries instead of dynamic SQL generation: SELECT * FROM users WHERE username=? JAVA EE use strongly typed “PreparedStatement” in .NET use “SqlCommand” with “SqlParameters” Use stored procedures to reduce the risk of SQL injection (no SPs with dynamically build queries! you need to pass parameters) Filter user input to remove special characters: ' " ` ; * % _ =&\|*?~<>^()[]{}$\n\r Limit write database privileges for application’s Functional ID (no DROP privileges!) Avoid detailed error messages (e.g. SQL Exception Information) that are useful to an attacker

A3: Malicious File Execution Issues Parameter manipulations leading to command execution Upload function can be used to upload malicious scripts. Threat Arbitrary commands can be run in the application context by the operating system Malicious files (e.g. script) can be executed on the application server

A3: Malicious File Execution - Insecure Software Root Cause String[] cmdArray = new String[2]; // String array to store command Runtime runtime = Runtime.getRuntime(); try { cmdArray[0] = "cmd.exe /C" ; String fromRequest = request.getParameter("cmd"); cmdArray[1] = "dir \""+ fromRequest +"\""; Process process = runtime.exec(cmdArray); } …

A3: Malicious File Execution – How To Find the Vulnerability If a user passes the following information in the cmd parameter: cmd= %3B+mkdir+hackerDirectory At the code level: cmdArray[0] = "cmd.exe /C" ; String fromRequest = “ %3B+mkdir+hackerDirectory ” cmd[1] = "dir \""+fromRequest+"\""; Process process = runtime.exec(cmd); Final command executed is : cmd.exe /C “dir; mkdir hackerDirectory”

A3: Malicious File Execution – Secure Coding Requirement User controllable input should not be used when executing commands on the operating system Outline all acceptable values for the user input (white list) and reject all other values (default deny) before executing the command For certain transactions, a query or hash table lookup may be necessary to verify if the specified value is appropriate Make sure that encoded commands are escaped before execution

A4: Insecure Direct Object Reference Issue Occurs when a developer exposes an invalidated reference to an internal implementation object, such as a file, directory, database record, or key, as a URL or form parameter Threat An attacker can manipulate direct object references to access other objects without authorization, unless an access control check is in place.

A4: Insecure Direct Object Reference: Insecure Root Causes This code can be attacked to access the file system since allow user input to specify filenames and path: <select name="language"><option value="fr">Français</option></select> ……require_once ($_REQUEST['language’]."lang.php"); An attacker can change the cartID parameter to whatever cart they want: int cartID = Integer.parseInt( request.getParameter( " cartID " ) ); String query = "SELECT * FROM table WHERE cartID=" + cartID;

A4: Insecure Direct Object Reference: How You Can Find If You Are Vulnerable Black Box Testing Check if user parameters can be manipulated to access other pages without authorization. Example access to object via parameter manipulation http:// www.payroll.com?PayStub =Bob becomes http:// www.payroll.com?PayStub = BobBoss White Box Testing Check that object references to users are validated Check user entitlements to object Check for any trusted user controlled input when specify filenames, paths etc

A4: Insecure Direct Object Reference - How You Can Find If You Are Vulnerable

A4: Insecure Direct Object Reference - Secure Coding Requirement Avoid exposing direct object references to users by using an index , indirect reference map, or other indirect method that is easy to validate. If a direct object reference must be used, ensure that the user is authorized before using it. Avoid exposing your private object references to users whenever possible, such as primary keys or filenames Validate any private object references extensively with an "accept known good" approach Verify authorization to all referenced objects Use an index value or a reference map to prevent parameter manipulation attacks.

A5:Cross Site Request Forgery Issue: A CSRF attack forces a logged-on victim’s browser to send a request to a vulnerable web application, which then performs the chosen action on behalf of the victim. Any web application without a build in CSRF control is vulnerable Threats: May direct the user to invoke logouts and steal user credentials. In bank application might invoke processing requests such as transfer of funds. It can also be used to make changes in the DSL router (Jeremiah Grossman in BlackHat 2006: Hacking Intranet Sites From the Outside)

A5:Cross Site Request Forgery- in-secure software root causes Non re-authenticated high risk transactions <img src="http://www.bank.com/transfer.do?frmAcct=document.form.frmAcct& toAcct=4345754&toSWIFTid=434343&amt=3434.43"> Auto-POST of confidential data <form> <input type="test" name="name" value="John"/> <input type="test" name="lastname" value="Dawson"/> <input type="submit"/> </form>

A5: CSRF : How You Can Find If You Are Vulnerable Check source code for forms that authorize requests on automatic credentials (session cookies, remember me functionality, SSO tokens) Auto-Posting forms <img>, <iFrame> and <script> tags that submit confidential data, perform non re-authenticated transactions XMLHTTPRequests Some automated scanners can detect CSRF today Record and replay transactions, manually check for attack vectors <img src="http://www.example.com/logout.php">

A5: CSRF : Secure Coding Requirements Insert custom random tokens into every form and URL <form action="/transfer.do" method="post"> <input type="hidden" name="8438927730" value="43847384383"> … </form> Make sure there a no XSS vulnerabilities Re-authenticate and perform out of band verification when performing high risk transactions Do not use GET requests for sensitive data or to perform high risk transactions For ASP.NET set ViewStateUserKey (similar check as random token)

A6: Information Leakage and Improper Error Handling Issue Coding errors in exception handling and error reporting can leak information about the application or the user Threats Detailed error handling, stack traces in default error messages can disclose application information that can be useful for a potential attacker Non generic error messages can be used for enumeration of valid user credentials Error codes in URL parameters can give insight to validation of user credentials

A6: Information Leakage and Improper Error Handling

A6:Information Leakage and Improper Error Handling- insecure software root cause Declarative setting in web.config file customErrors set to Off and no custom re-direct <customErrors mode=“Off”/> Error message and stack trace is displayed to the user uisng Server.GetLastError().ToString() <script language="C#" runat="server"> Sub Page_Error(Source As Object, E As EventArgs) Dim message As String = "<font face=verdana color=red><h1>" & Request.Url.ToString()& "</h1>" & "<pre><font color='red'>" & Server.GetLastError().ToString()& "</pre></font>" Response.Write(message) // display message End Sub </script>

A6:Information Leakage and Improper Error Handling- How You Can Find If You Are Vulnerable: Black Box Testing Force errors to verify account harvesting vulnerabilities “ The password you entered was not recognized. Please enter it again Force errors to verify information disclosure via exception handling: [ SqlException (0x80131904): An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections..

A6:Information Leakage and Improper Error Handling- How You Can Find If You Are Vulnerable: White Box Testing JAVA Information leakage can occur when developers use printStackTrace() and getStackTrace() exception methods .NET Information leakage can occur when developers use objects such as System.Exception with ApplicationException and SystemException and Exception object StackTrace

A6:Information Leakage and Improper Error Handling -Secure Coding Requirement Made exception information only be used as debugging information that is not part of production release code. Use Log4jLogger to log exception error messages securely Use declarative programming setting in “web.config” file and set “customErrors” to On and “mode=RemoteOnly”. Use centrailized exception handling (e.g. structs ActionMessages & ActionErrors) Do not display specific errors that allow for account harvesting

Broken Authentication Issues Flaws in this area most frequently involve using weak or no authentication as well in-secure password management, weak passwords, remember me features and “autocomplete” set OFF in web forms, weak secret answer combination for password reset Broken Authentication Threats Flaws can lead to the spoofing of the credentials in transit, man in the middle attacks, brute forcing of password and guessing of passwords A7: Broken Authentication and Session Management

Session Management Issues Flaws in this area most frequently involve the failure to protect credentials and session tokens through their lifecycle. Common issues include: session tokens not re-issued after authentication, not marked secure passed in clear passed via GET requests with guessable values remaining active after logout and idle logout. Session Management Threats These flaws can lead to the hijacking of user or administrative accounts, undermine authorization and accountability controls, and cause privacy violations. A7:Broken Authentication and Session Management

A7: Broken Authentication - insecure software root cause Http Cookie MyCookie; MyCookie = Request.Cookies [“CookiesLoginAttempts”]; MyCookie.Expires=now.AddHours(10); //decrement int logInAtt=Convert.ToInt32(MyCookie.Value.ToString()); CookieVal=int.Parse (MyCookie.Value.ToString()); If (CookieVal >0) CookieVal-=1; //store in response cookie HttpCookie AttemptCntCookie = new HttpCookie (“CookieLoginAttempts”); AttemptCntCookie.Value =CookieVal.ToString();

A7: Session Management - insecure software root cause Cookies with confidential information Set-Cookie: userid=jdoe; expires=Thu, 01-Jun-2006 19:16:08 GMT; path=/ Set-Cookie: password=xxxxxxx; expires=Thu, 01-Jun-2006 19:16:08 GMT; path=/ Cookies not marked Secure Set-Cookie: name=newvalue; expires=date; path=/; domain=.example.org.

A7: Broken Authentication - How You Can Find If You Are Vulnerable Automated Tools Most of automated scanning tool can only identify use of weak authentication such as basic authentication, autocomplete OFF in web forms and remember me functionality Manual Test Best way to identify weak passwords (complexity), flaws in password reset and password change, timeouts and logoff functionality, use of SSL Source Code Analysis For checking authentication setting in configuration files (e.g. authentication mode="Forms“)

A7: Session Management - How You Can Find If You Are Vulnerable Automated Tools Most of automated scanning tool can only identify session cookies not set with secure flag, passed via GET instead of POST and unpredictability (e.g. CookieDigger) Manual Ethical Hacking with Web Proxy Best way to find weak session management, session invalidation at logout and re-issuance after authentication Source Code Analysis For flaws in user and session management

A7: Session Management -Secure Coding Requirements Session Management Consider using sessionID and manage session on the server. Session IDs Invalidate the existing Session ID before authentication Issue a new Session ID after authentication Invalidate this Session ID on logout Set secure flag defaults to TRUE Pass session IDs in secure cookies instead of in URL parameters Use POST instead of GET when passing sensitive parameters Should be random (128 bit)

A7: Broken Authentication -Secure Coding Requirement Authentication Do not use weak form authentication such as BASIC or NTLM Ensure that SSL is used to protect credentials in transit Ensure that logins start with an encrypted web page Ensure that logouts are available in every page Use only shared secrets in challenge/responses Use trusted authentication (e.g. SSO) not impersonation Implement idle time-out Passwords Enforce password complexity, require old passwords for setting new, use challenge/response and out of band for re-setting passwords, store them with irreversible encryption

Issues Failing to protecting sensitive data with cryptography Failing to encrypt sensitive data because of either using weak encryption algorithms or short encryption keys. Home-grown encryption Failure to protect secrets such as private keys via hard-coding and unprotected access Threats Disclosure of customer sensitive information, Exposure of authentication data to unauthorized users Exposure of secrets such as keys and challenge response answers A8:Insecure Cryptographic Storage

A8: insecure Cryptographic Storage - insecure software root cause Hard-coding of passwords int VerifyPwd(String password) { if (passwd.Equals("68af404b513073584c4b6f22b6c63e6b")) { } return(0) return(1); } Errors coding cryptography public static String digest(String password) { MessageDigest md5 =MessageDigest.getInstance(“MD5"); byte[] hash = md5.update(password.getBytes()); return makeStringFromBytes(hash);}

A8: Insecure Cryptographic Storage - How You Can Find If You Are Vulnerable Automated Source Code Analysis Can verify instances of use of unsafe algorithms (MD5, DES, SHA1) as well as hard-coded keys and credentials Manual Source Code Analysis Home grown cryptography such as missing to use salt and seed when using digests key sizes Failing to use encryption for sensitive data and authentication data Weak keys and shared secrets management.

A8: Insecure Cryptographic Storage -Secure Coding Requirements Use approved algorithms (e.g. AES, RSA, SHA-256 instead of Blowfish, RC4, SHA1, MD5) and recommended key strength (128 bit for symmetric and 1048 for public) Encrypt authentication credentials in storage and transit Protect PII and customer sensitive data in storage and transit as appropriate Do not store credit card data (CVV2, magnetic strip information) see PCI compliance Store keys in secure repositories Use HSM and secure key storage such as CryptoAPI or Java Key Store

Issues Failure to encrypt network traffic to protect sensitive communications. Not using SSL for communication with end users as well as the back-end. Threats Identity theft, financial fraud Non-compliance with privacy regulations and standards Loss of sensitive data such as credit card information, bank account information and health care information A9: Insecure Communication

A9 Insecure Communication - insecure software root cause Lack of configuration of SSL on the web server secure connection properties are not set to true or left commented out. Tomcat 3.3. Example <Http10Connector port="8443" secure="true" keystore="/var/tomcat/conf/keystore" keypass="mynewpass" clientauth="false" />

A9 Insecure Communication - How You Can Find If You Are Vulnerable Vulnerability scanning tools Can verify that SSL is used Can only verify front end not back end Foundstone SSL digger can verify encryption strength (strong chipers enabled) Manual Test Old browsers such as Netscape 7.2 have custom setting for SSL that can be used to verify SSL configuration Code Review Can verify use of API that enable SSL connection in the back end (e.g. middle-tier and database, directories)

A9 Insecure Communication - How You Can Find If You Are Vulnerable

A9: Insecure Communication -Secure Coding Requirement Use SSL For all connections that are authenticated When transmitting credentials, credit card details, health and other private information Use transport layer and link layer security Between web servers and application servers and back end systems and repositories For PCI compliance You much protect credit card holder data in transit (mandatory by 2008 for merchants and anyone dealing with CC)

Issues URL web page access is enforced via security by obscurity Failure to enforce users role base access controls to limit access to web pages Threats A motivated, skilled, or just plain lucky attacker may be able to predict the location of web pages and access these pages, invoke functions, and view data. A10: Failure to restrict URL access

A10 Failure to restrict URL access - insecure software root cause Typically this is a security flaw, server side RBAC to set which web pages a user should be given access to: if (sess.getCurrentUser(). NormalUser ()) { URLList.add(“View Customer Details", "/jsp/Customer.do?action=view&id=“ + custId)); } Else {//must be a super user URLList.add(“View Customer Details", "/jsp/Customer.do?action=view&id=“ + custId)); URLList.add(“Edit Customer Details", "/jsp/Customer.do? action=edit&id=“ + custId)); URLList.add(“Delete Customer", "/jsp/Customer.do?action=delete&id=“ + custId)); }

A10 Failure to restrict URL access - How You Can Find If You Are Vulnerable Automated approaches A scanning tool, like Nikto has the ability to search for existent files and directories based on a database of well-know resources Static analysis tools are not contextual based and cannot find access controls in the code and link the presentation layer with the business logic. Manual approaches Verify the access control mechanism via source code analysis and penetration test. By logging on as user and super user/admin and by forcing access to different web pages can verify that RBAC is enforced.

A10: Failure to restrict URL access -Secure Coding Requirement RBAC Ensure that RBAC is enforced on the server side to enforce which user has access to which web page Do not use security by obscurity No HIDDEN parameters to enforce which web pages are accessible Enforce white list filtering to which web pages should be accessible only allow file types that you intend to serve, e.g., .html, .pdf, .php. block any attempts to access log files, xml files, etc. that you never intend to serve directly.

OWASP Top 10 And Insecure Software Root Causes

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