OWASP Top 10 Vulnerabilities For Application Security

While Developing Applications, Security and Best Practices are revolving around Developers Mind. What to Do ? or What they should avoid? Which pattern to follow?, How to make Application Security-proof. As there are numerous hundreds of Vulnerabilities. OWASP has issued These TOP 10 Vulnerabilities in 2013 as the Most Common Security Potholes developers fall onto.

Have a look..

OWASP Top 10

OWASP Top 10 – 2013 (New)

·         A1 – Injection- Injection flaws, such as SQL, OS, and LDAP injection occur when untrusted data is sent to an interpreter as part of a command or query. The attacker’s hostile data can trick the interpreter into executing unintended commands or accessing data without proper authorization.
·      A2 – Broken Authentication and Session Management- Application functions related to authentication and session management are often not implemented correctly, allowing attackers to compromise passwords, keys, or session tokens, or to exploit other implementation flaws to assume other users’ identities.
·      A3 – Cross-Site Scripting (XSS)- XSS flaws occur whenever an application takes untrusted data and sends it to a web browser without proper validation or escaping. XSS allows attackers to execute scripts in the victim’s browser which can hijack user sessions, deface web sites, or redirect the user to malicious sites.
·      A4 – Insecure Direct Object References- A direct object reference occurs when a developer exposes a reference to an internal implementation object, such as a file, directory, or database key. Without an access control check or other protection, attackers can manipulate these references to access unauthorized data.
·      A5 – Security Misconfiguration- Good security requires having a secure configuration defined and deployed for the application, frameworks, application server, web server, database server, and platform. Secure settings should be defined, implemented, and maintained, as defaults are often insecure. Additionally, software should be kept up to date.
·      A6 – Sensitive Data Exposure- Many web applications do not properly protect sensitive data, such as credit cards, tax IDs, and authentication credentials. Attackers may steal or modify such weakly protected data to conduct credit card fraud, identity theft, or other crimes. Sensitive data deserves extra protection such as encryption at rest or in transit, as well as special precautions when exchanged with the browser.
·       A7 – Missing Function Level Access Control-Most web applications verify function level access rights before making that functionality visible in the UI. However, applications need to perform the same access control checks on the server when each function is accessed. If requests are not verified, attackers will be able to forge requests in order to access functionality without proper authorization.
·       A8 – Cross-Site Request Forgery (CSRF)- A CSRF attack forces a logged-on victim’s browser to send a forged HTTP  request, including the victim’s session cookie and any other automatically included authentication information, to a vulnerable web application. This allows the attacker to force the victim’s browser to generate requests the vulnerable application thinks are legitimate requests from the victim.
·       A9 – Using Known Vulnerable Components- Components, such as libraries, frameworks, and other software modules, almost always run with full privileges. If a vulnerable component is exploited, such an attack can facilitate serious data loss or server takeover. Applications using components with known vulnerabilities may undermine application defenses and enable a range of possible attacks and impacts.
·       A10 – Unvalidated Redirects and Forwards-Web applications frequently redirect and forward users to other pages and websites, and use untrusted data to determine the destination pages. Without proper validation, attackers can redirect victims to phishing or malware sites, or use forwards to access unauthorized pages.

A1 Injection

Example Attack Scenarios Scenario #1: The application uses untrusted data in the construction of the following vulnerable SQL call:

String query = "SELECT * FROM accounts WHERE userID='" + id.Text + "'";

In this case, the attacker modifies the ‘id’ parameter value in her browser to send: ' or '1'='1. For example: http://example.com/app/accountView?id=' or '1'='1

Thus Query becomes SELECT * FROM accounts WHERE userID= or 1=1, which would be always True.

Prevent Injection

Primary Defenses:

·Option #1: Use of Prepared Statements (Parameterized Queries)-

                         SqlCommand command = new SqlCommand(commandText, connection);
                         command.Parameters.Add("@ID", SqlDbType.Int);
                         command.Parameters["@ID"].Value = customerID;

·Option #2: Use of Stored Procedures
Option #3: Escaping all User Supplied Input

Additional Defenses:
· Also Enforce: Least Privilege

· Also Perform: White List Input Validation

A2 – Broken Authentication and Session Management

Authentication and session management includes all aspects of handling user authentication and managing active sessions. Authentication is a critical aspect of this process, but even solid authentication mechanisms can be undermined by flawed credential management functions, including password change, forgot my password, remember my password, account update, and other related functions. Because “walk by” attacks is likely for many web applications, all account management functions should require reauthentication even if the user has a valid session id.

User authentication on the web typically involves the use of a userid and password. Stronger methods of authentication are commercially available such as software and hardware-based cryptographic tokens or biometrics, but such mechanisms cost prohibitive for most web applications. A wide array of account and session management flaws can result in the compromise of user or system administration accounts. Development teams frequently underestimate the complexity of designing an authentication and session management scheme that adequately protects credentials in all aspects of the site. Web applications must establish sessions to keep track of the stream of requests from each user. HTTP does not provide this capability, so web applications must create it themselves. Frequently, the web application environment provides a session capability, but many developers prefer to create their own session tokens. In either case, if the session tokens are not properly protected, an attacker can hijack an active session and assume the identity of a user. Creating a scheme to create strong session tokens and protect them throughout their lifecycle has proven elusive for many developers. Unless all authentication credentials and session identifiers are protected with SSL at all times and protected against disclosure from other flaws, such as cross-site scripting, an attacker can hijack a user’s session and assume their identity.

Am I Vulnerable To 'Broken Authentication and Session Management'?

Are session management assets like user credentials and session IDs properly protected? You may be vulnerable if:

1. User authentication credentials aren’t protected when stored using hashing or encryption.

2. Credentials can be guessed or overwritten through weak account management functions (e.g., account creation, change password, recover password, weak session IDs).

3. Session IDs are exposed in the URL (e.g., URL rewriting).

4. Session IDs are vulnerable to session fixation attacks.

5. Session IDs don’t timeout, or user sessions or authentication tokens, particularly single sign-on (SSO) tokens, aren’t properly invalidated during logout.

6. Session IDs aren’t rotated after successful login.

7. Passwords, session IDs, and other credentials are sent over unencrypted connections

A3 – Cross-Site Scripting (XSS)-

Cross-Site Scripting (XSS) attacks are a type of injection, in which malicious scripts are injected into otherwise benign and trusted web sites. XSS attacks occur when an attacker uses a web application to send malicious code, generally in the form of a browser side script, to a different end user. Flaws that allow these attacks to succeed are quite widespread and occur anywhere a web application uses input from a user within the output it generates without validating or encoding it.

An attacker can use XSS to send a malicious script to an unsuspecting user. The end user’s browser has no way to know that the script should not be trusted, and will execute the script. Because it thinks the script came from a trusted source, the malicious script can access any cookies, session tokens, or other sensitive information retained by the browser and used with that site. These scripts can even rewrite the content of the HTML page. For more details on the different types of XSS flaws, see:

Types of Cross-Site Scripting

There are two different types of XSS flaws: 1) Stored and 2)Reflected, and each of these can occur on the a) Server or b) on theClient.

Am I Vulnerable To 'Cross-Site Scripting (XSS)'?

You are vulnerable if you do not ensure that all user supplied input is properly escaped, or you do not verify it to be safe via server-side input validation, before including that input in the output page. Without proper output escaping or validation, such input will be treated as active content in the browser. If Ajax is being used to dynamically update the page, are you using safe JavaScript APIs? For unsafe JavaScript APIs, encoding or validation must also be used.

Automated tools can find some XSS problems automatically. However, each application builds output pages differently and uses different browser side interpreters such as JavaScript, ActiveX, Flash, and Silverlight, making automated detection difficult. Therefore, complete coverage requires a combination of manual code review and penetration testing, in addition to automated approaches.

How Do I Prevent 'Cross-Site Scripting (XSS)'?

Preventing XSS requires separation of untrusted data from active browser content.

1. The preferred option is to properly escape all untrusted data based on the HTML context (body, attribute, JavaScript, CSS, or URL) that the data will be placed into.

2. Positive or “whitelist” server-side input validation is also recommended as it helps protect against XSS, but is not a complete defense as many applications require special characters in their input. Such validation should, as much as possible, validate the length, characters, format, and business rules on that data before accepting the input.

3. For rich content, consider auto-sanitization libraries like OWASP’s AntiSamy or the Java HTML Sanitizer Project.

4. Consider Content Security Policy (CSP) to defend against XSS across your entire site.

A4 – Insecure Direct Object References

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. An attacker can manipulate direct object references to access other objects without authorization, unless an access control check is in place.

For example, in Internet Banking applications, it is common to use the account number as the primary key. Therefore, it is tempting to use the account number directly in the web interface. Even if the developers have used parameterized SQL queries to prevent SQL injection, if there is no extra check that the user is the account holder and authorized to see the account, an attacker tampering with the account number parameter can see or change all accounts.

Am I Vulnerable To 'Insecure Direct Object References'?

The best way to find out if an application is vulnerable to insecure direct object references is to verify that all object references have appropriate defenses. To achieve this, consider:

1. For direct references to restricted resources, does the application fail to verify the user is authorized to access the exact resource they have requested?

2. If the reference is an indirect reference, does the mapping to the direct reference fail to limit the values to those authorized for the current user?

Code review of the application can quickly verify whether either approach is implemented safely. Testing is also effective for identifying direct object references and whether they are safe. Automated tools typically do not look for such flaws because they cannot recognize what requires protection or what is safe or unsafe.

How Do I Prevent 'Insecure Direct Object References'?

Preventing insecure direct object references requires selecting an approach for protecting each user accessible object (e.g., object number, filename):

1. Use per user or session indirect object references. This prevents attackers from directly targeting unauthorized resources. For example, instead of using the resource’s database key, a drop-down list of six resources authorized for the current user could use the numbers 1 to 6 to indicate which value the user selected. The application has to map the per-user indirect reference back to the actual database key on the server. OWASP’s ESAPI includes both sequential and random access reference maps that developers can use to eliminate direct object references.

2. Check access. Each use of a direct object reference from an untrusted source must include an access control check to ensure the user is authorized for the requested object.

A5  - Security Misconfiguration 

Security misconfiguration can happen at any level of an application stack, including the platform, web server, application server, database, framework, and custom code. Developers and system administrators need to work together to ensure that the entire stack is configured properly. Automated scanners are useful for detecting missing patches, misconfigurations, use of default accounts, unnecessary services, etc.

Am I Vulnerable To 'Security Misconfiguration'?

Is your application missing the proper security hardening across any part of the application stack? Including:

1. Is any of your software out of date? This includes the OS, Web/App Server, DBMS, applications, and all code libraries (see new A9).

2. Are any unnecessary features enabled or installed (e.g., ports, services, pages, accounts, privileges)?

3. Are default accounts and their passwords still enabled and unchanged?

4. Does your error handling reveal stack traces or other overly informative error messages to users?

5. Are the security settings in your development frameworks (e.g., Struts, Spring, ASP.NET) and libraries not set to secure values?

Without a concerted, repeatable application security configuration process, systems are at a higher risk.

How Do I Prevent 'Security Misconfiguration'?

The primary recommendations are to establish all of the following:

1. A repeatable hardening process that makes it fast and easy to deploy another environment that is properly locked down. Development, QA, and production environments should all be configured identically (with different passwords used in each environment). This process should be automated to minimize the effort required to set up a new secure environment.

2. A process for keeping abreast of and deploying all new software updates and patches in a timely manner to each deployed environment. This needs to include all code libraries as well (see new A9).

3. A strong application architecture that provides effective, the secure separation between components.

4. Consider running scans and doing audits periodically to help detect future misconfigurations or missing patches.

A6  - Sensitive Data Exposure

Attackers typically don’t break crypto directly. They break something else, such as steal keys, do man-in-the-middle attacks, or steal clear text data off the server, while in transit, or from the user’s browser. The most common flaw is simply not encrypting sensitive data. When crypto is employed, weak key generation and management, and weak algorithm usage are common, particularly weak password hashing techniques. Browser weaknesses are very common and easy to detect, but hard to exploit on a large scale. External attackers have difficulty detecting server-side flaws due to limited access and they are also usually hard to exploit.

Am I Vulnerable To 'Sensitive Data Exposure'?

The first thing you have to determine is which data is sensitive enough to require extra protection. For example, passwords, credit card numbers, health records, and personal information should be protected. For all such data:

1. Is any of this data stored in clear text long term, including backups of this data?

2. Is any of this data transmitted in clear text, internally or externally? Internet traffic is especially dangerous.

3. Are any old/weak cryptographic algorithms used?

4. Are weak crypto keys generated, or is proper key management or rotation missing?

5. Are any browser security directives or headers missing when sensitive data is provided by / sent to the browser?

How Do I Prevent 'Sensitive Data Exposure'?

The full perils of unsafe cryptography, SSL usage, and data protection are well beyond the scope of the Top 10. That said, for all sensitive data, do all of the following, at a minimum:

1. Considering the threats you plan to protect this data from (e.g., insider attack, external user), make sure you encrypt all sensitive data at rest and in transit in a manner that defends against these threats.

2. Don’t store sensitive data unnecessarily. Discard it as soon as possible. Data you don’t have can’t be stolen.

3. Ensure strong standard algorithms and strong keys are used, and proper key management is in place.

4. Ensure passwords are stored with an algorithm specifically designed for password protection, such as bcrypt, PBKDF2, or scrypt.

5. Disable autocomplete on forms collecting sensitive data and disable caching for pages that contain sensitive data.

A7  - Missing Function Level Access Control

Most web applications verify function level access rights before making that functionality visible in the UI. However, applications need to perform the same access control checks on the server when each function is accessed. If requests are not verified, attackers will be able to forge requests in order to access functionality without proper authorization.

Am I Vulnerable To 'Missing Function Level Access Control'?

The best way to find out if an application has failed to properly restrict function level access is to verify every application function:

1. Does the UI show navigation to unauthorized functions?

2. Are server side authentication or authorization checks missing?

3. Are server side checks done that solely rely on information provided by the attacker?

Using a proxy, browse your application with a privileged role. Then revisit restricted pages using a less privileged role. If the server responses are alike, you're probably vulnerable. Some testing proxies directly support this type of analysis.

You can also check the access control implementation in the code. Try following a single privileged request through the code and verifying the authorization pattern. Then search the codebase to find where that pattern is not being followed.

Automated tools are unlikely to find these problems.

How Do I Prevent 'Missing Function Level Access Control'?

Your application should have a consistent and easy to analyze authorization module that is invoked from all of your business functions. Frequently, such protection is provided by one or more components external to the application code.

1. Think about the process for managing entitlements and ensure you can update and audit easily. Don’t hard code.

2. The enforcement mechanism(s) should deny all access by default, requiring explicit grants to specific roles for access to every function.

3. If the function is involved in a workflow, check to make sure the conditions are in the proper state to allow access.

NOTE: Most web applications don’t display links and buttons to unauthorized functions, but this “presentation layer access control” doesn’t actually provide protection. You must also implement checks in the controller or business logic.

A8  - Cross-Site Request Forgery (CSRF)

A CSRF attack forces a logged-on victim’s browser to send a forged HTTP  request, including the victim’s session cookie and any other automatically included authentication information, to a vulnerable web application. This allows the attacker to force the victim’s browser to generate requests the vulnerable application thinks are legitimate requests from the victim.

Am I Vulnerable To 'Cross-Site Request Forgery (CSRF)'?

To check whether an application is vulnerable, see if any links and forms lack an unpredictable CSRF token. Without such a token, attackers can forge malicious requests. An alternate defense is to require the user to prove they intended to submit the request, either through reauthentication, or some other proof they are a real user (e.g., a CAPTCHA).

Focus on the links and forms that invoke state-changing functions, since those are the most important CSRF targets.

You should check multistep transactions, as they are not inherently immune. Attackers can easily forge a series of requests by using multiple tags or possibly JavaScript.

Note that session cookies, source IP addresses, and other information automatically sent by the browser don’t provide any defense against CSRF since this information is also included in forged requests.

How Do I Prevent 'Cross-Site Request Forgery (CSRF)'?

Preventing CSRF usually requires the inclusion of an unpredictable token in each HTTP request. Such tokens should, at a minimum, be unique per user session.

1. The preferred option is to include the unique token in a hidden field. This causes the value to be sent in the body of the HTTP request, avoiding its inclusion in the URL, which is more prone to exposure.

2. The unique token can also be included in the URL itself, or a URL parameter. However, such placement runs a greater risk that the URL will be exposed to an attacker, thus compromising the secret token.
OWASP’s CSRF Guard can automatically include such tokens in Java EE, .NET, or PHP apps. OWASP’s ESAPI includes methods developers can use to prevent CSRF vulnerabilities.


3. Requiring the user to reauthenticate, or prove they are a user (e.g., via a CAPTCHA) can also protect against CSRF.

A9 - Using Components with Known Vulnerabilities

Components, such as libraries, frameworks, and other software modules, almost always run with full privileges. If a vulnerable component is exploited, such an attack can facilitate serious data loss or server takeover. Applications using components with known vulnerabilities may undermine application defenses and enable a range of possible attacks and impacts.

Am I Vulnerable To 'Using Components with Known Vulnerabilities'?

In theory, it ought to be easy to figure out if you are currently using any vulnerable components or libraries. Unfortunately, vulnerability reports for commercial or open source software do not always specify exactly which versions of a component are vulnerable in a standard, searchable way. Further, not all libraries use an understandable version numbering system. Worst of all, not all vulnerabilities are reported to a central clearinghouse that is easy to search, although sites like CVE and NVD are becoming easier to search.

Determining if you are vulnerable requires searching these databases, as well as keeping abreast of project mailing lists and announcements for anything that might be a vulnerability. If one of your components does have a vulnerability, you should carefully evaluate whether you are actually vulnerable by checking to see if your code uses the part of the component with the vulnerability and whether the flaw could result in an impact you care about.

How Do I Prevent 'Using Components with Known Vulnerabilities'?

One option is not to use components that you didn’t write. But that’s not very realistic.

Most component projects do not create vulnerability patches for old versions. Instead, most simply fix the problem in the next version. So upgrading to these new versions is critical. Software projects should have a process in place to:

1. Identify all components and the versions you are using, including all dependencies. (e.g., theversions plugin).

2. Monitor the security of these components in public databases, project mailing lists, and security mailing lists, and keep them up to date.

3. Establish security policies governing component use, such as requiring certain software development practices, passing security tests, and acceptable licenses.

4. Where appropriate, consider adding security wrappers around components to disable unused functionality and/ or secure weak or vulnerable aspects of the component.

A10-Unvalidated Redirects and Forwards

Web applications frequently redirect and forward users to other pages and websites, and use untrusted data to determine the destination pages. Without proper validation, attackers can redirect victims to phishing or malware sites, or use forwards to access unauthorized pages.

Am I Vulnerable To 'Unvalidated Redirects and Forwards'?

The best way to find out if an application has any unvalidated redirects or forwards is to:

1. Review the code for all uses of redirect or forward (called a transfer in .NET). For each use, identify if the target URL is included in any parameter values. If so, if the target URL isn’t validated against a whitelist, you are vulnerable.

2. Also, spider the site to see if it generates any redirects (HTTP response codes 300-307, typically 302). Look at the parameters supplied prior to the redirect to see if they appear to be a target URL or a piece of such a URL. If so, change the URL target and observe whether the site redirects to the new target.

3. If code is unavailable, check all parameters to see if they look like part of a redirect or forward URL destination and test those that do.

How Do I Prevent 'Unvalidated Redirects and Forwards'?

Safe use of redirects and forwards can be done in a number of ways:

1. Simply avoid using redirects and forwards.

2. If used, don’t involve user parameters in calculating the destination. This can usually be done.

3. If destination parameters can’t be avoided, ensure that the supplied value is valid, and authorized for the user.
It is recommended that any such destination parameters be a mapping value, rather than the actual URL or portion of the URL, and that server side code translate this mapping to the target URL.
Applications can use ESAPI to override the sendRedirect() method to make sure all redirect destinations are safe.

Avoiding such flaws is extremely important as they are a favorite target of phishers trying to gain the user’s trust.


Be Safe and Keep your Application Safer. Happy Coding !!!