1. SEC835
OWASP Top Ten Project

2. Top Ten Web App Vulnerabilities
OWASP top ten web application vulnerabilities – 2007 report
Vulnerabilities
A1 - Cross Site Scripting (XSS)
A2 - Injection Flaws
A3 - Malicious File Execution
A4 - Insecure Direct Object Reference
A5 - Cross Site Request Forgery (CSRF)
A6 - Information Leakage and Improper Error Handling
A7 - Broken Authentication and Session Management
A8 - Insecure Cryptographic Storage
A9 - Insecure Communications
A10 - Failure to Restrict URL Access

3. Top Ten Web App Vulnerabilities
OWASP top ten web application vulnerabilities – 2010 report
Vulnerabilities
A1 - Injection Flaws
A2 - Cross Site Scripting (XSS)
A3 – Broken Authentication and Session Management
A4 - Insecure Direct Object Reference
A5 - Cross Site Request Forgery (CSRF)
A6 – Security misconfiguration
A7 - Insecure Cryptographic Storage
A8 - Failure to Restrict URL Access
A9 – Insufficient transport layer protection
A10 – Unvalidated redirect and forwards

4. Cross-Site Scripting and Injection Flows
See Week 10 materials

5. Insecure Direct Object Reference
A direct object reference occurs when a developer exposes a reference to an internal implementation object, such as a file, directory, database record, or key, as a URL or form parameter. Attackers can manipulate those references to access other objects without authorization.

6. IDOR Protection
Avoid exposing direct object references to users by using either of
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.
Validate any private object references extensively with a white list approach

7. Cross-Site Request Forgery
CSRF forces a victim browser to send a request to a vulnerable application, after a user is logged-on. A user can be tricked by an image link for example.
A vulnerable application (or html page) starts acting on behalf of a user, using the opened session. It can perform actions designed by the attacker, e.g. transfer money from the victim account
Affected page performs the action that appears to come from a legitimate user
The malicious code often resides on other site, not on the victim site, that’s why named as cross-site

8. Cross-Site Request Forgery
XSS exploits the trust a user has for a particular site, when CSRF exploits the trust a site has for a particular user
CSRF occurs when the application rely solely on automatically submitted credentials such as session cookies, basic authentication credentials, source IP addresses, SSL certificates, or Windows domain credentials.

9. CSRF Protection
A user must be re-authenticated by generating and then requiring some type of authorization token that is not automatically submitted by the browser.
Insert custom random tokens into every form and URL that will not be automatically submitted by the browser
For sensitive data or value transactions, re-authenticate or use transaction signing
Do not use GET requests (URLs) for sensitive data or to perform value transactions. Use only POST methods when processing sensitive data from the user
POST alone is not sufficient. It must be combined with random tokens and re-authentication
Limit the lifetime of authentication cookies
Ensure that there are no XSS vulnerabilities in your application. XSS vulnerabilities are not required for CSRF success but may aggravate the CSRF result

10. Security misconfiguration
Security holes that occur due to wrong, weak, or contradicted configuration parameters
Mostly relate to network and servers configuration

11. Security misconfiguration protection
Standard hardening procedures must apply to all infrastructure sw/hw
Updates and patching
Application code version control

12. Insecure cryptographic store
The most common problems are:
Not encrypting sensitive data
Using home grown algorithms
Insecure use of strong algorithms
Continued use of proven weak algorithms (MD5, SHA-1, RC3, RC4, etc…)
Hard coding keys, and storing keys in unprotected stores

13. Strong crypto mechanism
Do not create cryptographic algorithms. Only use approved public algorithms such as AES, RSA public key cryptography, and SHA-256 or better for hashing.
Do not use weak algorithms, such as MD5 / SHA1. Favor safer alternatives, such as SHA-256 or better.
Generate keys offline and store private keys with extreme care. Never transmit private keys over insecure channels
Ensure that infrastructure credentials such as database credentials or MQ queue access details are properly secured (via tight file system permissions and controls), or securely encrypted and not easily decrypted by local or remote users
Ensure that encrypted data stored on disk is not easy to decrypt. For example, database encryption is worthless if the database connection pool provides unencrypted access.

14. Strong crypto mechanism (cont)
Data in rest must be encrypted with the highest possible granularity, relevant to the data’s sensitivity classification.
Field encryption will be implemented for highly sensitive data.
Data files, folders, or whole-disk encryption can be used to protect data as a batch function. However, if the data contains sensitive items, then field encryption must be implemented prior to using bulk encryption
Encryption keys must be protected at the same level or higher as the data.

15. Strong crypto mechanism (cont)
All keying materials must be destroyed immediately after use.
Encryption keys must not be hardcoded
Encryption keys must not be stored in audit logs.
An encryption key can be used for one purpose only.
Memory protection
Allocate two different buffers used for:
Plaintext data
Encrypted data
Erase data traces from the buffers immediately after use.

16. Failure to restrict URL access
Access to web pages thru “hidden" or "special" URLs, rendered only to administrators or privileged users in the presentation layer, but accessible to all users if they know it exists
Access to “hidden” files, such as static xml files without authorization
Code that enforces an access control policy but is out of date or insufficient
Code that evaluates privileges on the client but not on the server

17. URL access protection
Role-based access control to the application functions
Always ensure that administrative and high privilege actions are protected
Locate application libraries outside of the web root
Block access to all file types that your application should never serve

18. Insufficient transport layer protection
Failure to encrypt network traffic for all authenticated connections
Common flaws:
Only login activity is protected with SSL
Backend communication is not protected

19. Insufficient transport layer protection
Communication to end user always occurs over SSL
All sensitive actions are protected, not only login
Backend communication is protected with TLS

20. Unvalidated redirects and forwards
Without proper validation, attackers can redirect victims to phishing or malware sites, or use forwards to access unauthorized pages.

21. Unvalidated redirects and forwards - protection
Avoid using redirects and forwards
If used, don’t involve user parameters in calculating the destination.
If destination parameters can’t be avoided, ensure that the supplied value is valid, and authorized for the user.

22. For 2007 items
See below

23. Malicious File Execution
Occurs when a developer accepts file names or files from a user without validation
Typical examples include: .NET assemblies which allow URL file name arguments, or code which accepts the user’s choice of filename to include local files.
A common vulnerable construct:
include $_REQUEST['filename’];

24. Malicious File Execution (cont)
Other methods of attacks:
Hostile data being uploaded to session files, log data, and via image uploads (typical of forum software)
XML documents submitted by an attacker may have a hostile DTD that forces the XML parser to load a remote DTD, and parse and process the results

25. Protection This vulnerability is difficult to determine
Automatic testing is not capable to validate the use of parameters
Security remedy must start from the architecture and design
Ensure that the application will not use user-supplied input in any filename for any server-based resource (such as images, XML and XSL transform documents, or script inclusions), and will have firewall rules in place preventing new outbound connections to the Internet or internally back to any other server.

26. Protection (cont.) Recommendations Use indirect object reference map
Strong user data input validation (white list strategy)
Check any user supplied filenames or files
In Java, consider implementing a chroot jail or other sandbox mechanisms in order to isolate applications
In J2EE, ensure that security manager is enabled and permissions are controlled

27. Information leakage
See week 9 materials

28. Lab task Read OWASP Top Ten Project Articles Work on your spreadsheet
Crypto: cells E3, A19
IDOR: cells D3, A26
XSRF: cells F3, A21, A23
URL access: cells C3, A5
Transport Layer: cells G3, A24
Redirects and forwards: cells H3, A25

29. Useful links