06 Mar, 2023

Cross-Site Request Forgery (CSRF) via Flash

Vulnerability Assessment as a Service (VAaaS)

Tests systems and applications for vulnerabilities to address weaknesses.

Cross-Site Request Forgery (CSRF) via Flash is a type of cyber attack that targets web applications. In this attack, the attacker creates a malicious Flash file that is embedded in a webpage. When a user visits the page, the Flash file sends a request to the web application in the background without the user’s knowledge or consent. This request can perform any action that the user is authorized to perform on the web application, such as changing their password or transferring money.

CSRF via Flash is important for web security, Android and iOS security because it can lead to unauthorized access to sensitive information or actions on the web application. It can also lead to data theft, fraud, and other forms of cybercrime.

The overall risk and severity assessment for organizations depends on the nature of the web application and the types of data and actions that can be accessed through CSRF via Flash. Organizations should assess the risk of this type of attack and take appropriate measures to mitigate it, such as implementing CSRF tokens, disabling Flash, and using secure coding practices. They should also regularly test their web applications for vulnerabilities and educate their employees and customers on how to protect themselves from CSRF attacks.

Examples of vulnerable code on different programming languages

It’s important to note that CSRF via Flash is a relatively rare and outdated attack technique, and modern web frameworks have largely mitigated the risk of this type of attack. However, here are some examples of vulnerable code in Python, JavaScript, and HTML that could potentially be exploited in a CSRF via Flash attack:

Python:

This Python code defines a simple Flask app that allows a user to change their password by submitting a POST request to the /change_password endpoint. However, this code is vulnerable to CSRF via Flash because it doesn’t include a CSRF token in the form. An attacker could create a malicious Flash file that automatically submits a POST request to this endpoint with the user’s session cookie, effectively changing the user’s password without their knowledge or consent.

				
					from flask import Flask, request

app = Flask(__name__)

@app.route('/change_password', methods=['POST'])
def change_password():
    user_id = request.form['user_id']
    new_password = request.form['new_password']
    # Change the user's password in the database
    return 'Password changed successfully'

if __name__ == '__main__':
    app.run()
				
			

Java Script:

This JavaScript code defines a function that sends a POST request to a server endpoint that transfers money to a specified destination. However, this code is vulnerable to CSRF via Flash because it doesn’t include a CSRF token in the request headers or body. An attacker could create a malicious Flash file that automatically sends a POST request to this endpoint with the user’s session cookie, effectively transferring money without their knowledge or consent.

				
					function transfer_money(amount, destination) {
    var xhr = new XMLHttpRequest();
    xhr.open('POST', '/transfer_money', true);
    xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    xhr.send('amount=' + amount + '&destination=' + destination);
}
				
			

HTML:

This HTML code defines a simple form that allows a user to delete their account by submitting a POST request to the /delete_account endpoint. However, this code is vulnerable to CSRF via Flash because it doesn’t include a CSRF token in the form. An attacker could create a malicious Flash file that automatically submits a POST request to this endpoint with the user’s session cookie, effectively deleting the user’s account without their knowledge or consent.

				
					<form action="/delete_account" method="POST">
    <input type="hidden" name="user_id" value="123">
    <button type="submit">Delete Account</button>
</form>
				
			

Cross-Site Request Forgery (CSRF) via Flash types in cybersecurity

Simple GET-based attacks: In this type of attack, the attacker creates a malicious Flash file that sends a GET request to the target website in the background. The GET request contains the necessary parameters to perform a specific action on the website, such as changing the user’s password.

POST-based attacks: Similar to GET-based attacks, POST-based attacks use a malicious Flash file to send a POST request to the target website in the background. The POST request contains the necessary parameters to perform a specific action on the website, such as transferring money.

Cookie theft: In this form of attack, the attacker uses a malicious Flash file to steal the user’s session cookie from the vulnerable website. The attacker can then use the stolen cookie to perform actions on the website as if they were the authenticated user.

Clickjacking attacks: Clickjacking attacks involve tricking the user into clicking on a hidden button or link on a webpage, which executes a CSRF via Flash attack in the background.

Self-submitting forms: In this form of attack, the attacker creates a hidden form on a webpage that automatically submits a POST request to a vulnerable endpoint when the page is loaded. The POST request can perform any action that the user is authorized to perform on the website, such as deleting their account.

Ways of provoking Cross-Site Request Forgery (CSRF) via Flash

General ways:

Social engineering: An attacker can trick a user into clicking on a malicious link or opening a file that contains a malicious Flash file.

Malvertising: An attacker can place a malicious Flash file in an online advertisement, which can be automatically downloaded and executed when the user visits the website hosting the advertisement.

Watering hole attacks: An attacker can target a specific website that they know their target regularly visits and infect it with a malicious Flash file.

Specific ways:

Exploiting vulnerabilities in Flash: Attackers can exploit known vulnerabilities in Adobe Flash to execute a CSRF via Flash attack. This includes using zero-day vulnerabilities or known vulnerabilities that have not yet been patched by Adobe.

Injecting malicious Flash files: Attackers can inject a malicious Flash file into a vulnerable website by exploiting vulnerabilities in the website’s code or by exploiting third-party plugins that are vulnerable to attacks.

Man-in-the-middle attacks: Attackers can intercept the user’s traffic and inject a malicious Flash file into the webpage, allowing them to execute a CSRF via Flash attack.

Overall, organizations can mitigate the risk of CSRF via Flash attacks by implementing secure coding practices, regularly updating and patching software and plugins, monitoring network traffic for suspicious activity, and educating employees and customers on how to identify and prevent CSRF attacks.

Real world examples of Cross-Site Request Forgery (CSRF) via Flash

The Adobe Flash vulnerability: In 2018, researchers discovered a vulnerability in Adobe Flash that could allow attackers to execute a CSRF via Flash attack. The vulnerability was patched by Adobe, but organizations using outdated versions of Flash were at risk.

The Clickjacking campaign: In 2017, researchers discovered a campaign that used Clickjacking to execute a CSRF via Flash attack on vulnerable websites. The campaign targeted several popular websites, including eBay, Tumblr, and LinkedIn.

The eBay hack: In 2014, eBay suffered a data breach that was the result of a CSRF via Flash attack. The attackers used a Flash file to steal login credentials and personal information from eBay’s database.

The Yahoo! Mail vulnerability: In 2013, a vulnerability was discovered in Yahoo! Mail that could allow attackers to execute a CSRF via Flash attack. The vulnerability was quickly patched by Yahoo!, but users who did not update their software were at risk.

The Twitter hack: In 2010, a group of hackers used a CSRF via Flash attack to hijack the Twitter accounts of several high-profile users, including President Barack Obama and Britney Spears. The attackers used a Flash file to send unauthorized tweets from the hijacked accounts.

The Microsoft Silverlight vulnerability: In 2016, a vulnerability was discovered in Microsoft Silverlight that could allow attackers to execute a CSRF via Flash attack. The vulnerability was patched by Microsoft, but users who did not update their software were at risk.

The Facebook vulnerability: In 2011, a vulnerability was discovered in Facebook that could allow attackers to execute a CSRF via Flash attack. The vulnerability was quickly patched by Facebook, but users who did not update their software were at risk.

The WordPress vulnerability: In 2013, a vulnerability was discovered in WordPress that could allow attackers to execute a CSRF via Flash attack. The vulnerability was quickly patched by WordPress, but users who did not update their software were at risk.

The Drupal vulnerability: In 2014, a vulnerability was discovered in Drupal that could allow attackers to execute a CSRF via Flash attack. The vulnerability was quickly patched by Drupal, but users who did not update their software were at risk.

The Joomla vulnerability: In 2015, a vulnerability was discovered in Joomla that could allow attackers to execute a CSRF via Flash attack. The vulnerability was quickly patched by Joomla, but users who did not update their software were at risk.

Average CVSS score and risk assessment of Cross-Site Request Forgery (CSRF) via Flash

The average CVSS score for Cross-Site Request Forgery (CSRF) via Flash is dependent on the specific vulnerability being exploited, the impact of the attack, and the severity of the vulnerability. Generally, the CVSS score for CSRF via Flash attacks falls between 4.0 and 9.0, with a higher score indicating a more severe vulnerability.

In terms of risk assessment, CSRF via Flash attacks pose a significant risk to web applications that are vulnerable to this type of attack. Attackers can use CSRF via Flash attacks to trick users into performing actions on a website without their knowledge or consent, leading to unauthorized access, data theft, or other malicious activities. Additionally, CSRF via Flash attacks can be difficult to detect and mitigate, making them a persistent threat to organizations.

To mitigate the risk of CSRF via Flash attacks, organizations should ensure that their web applications are up to date and that all software vulnerabilities are patched promptly. Organizations can also use security tools and techniques, such as CSRF tokens and security headers, to protect against CSRF attacks. Finally, user education and awareness can be an effective way to prevent CSRF attacks by encouraging users to be cautious of suspicious links or unexpected actions on websites.

TOP 10 CWE for Cross-Site Request Forgery (CSRF) via Flash 

CWE-352: Cross-Site Request Forgery (CSRF) Description: CWE-352 is a common weakness that can allow attackers to trick users into performing actions on a web application without their knowledge or consent. This weakness can be exploited via Flash, among other methods. 

CWE-399: Resource Management Errors Description: CWE-399 refers to vulnerabilities related to improper handling of resources, such as files, memory, or network connections. CSRF via Flash attacks can exploit resource management errors in vulnerable web applications. 

CWE-400: Uncontrolled Resource Consumption (‘Resource Exhaustion’) Description: CWE-400 is a weakness that occurs when an application does not properly manage its resources, leading to a denial of service (DoS) condition. CSRF via Flash attacks can consume resources on a web application, leading to a DoS condition.  

CWE-601: URL Redirection to Untrusted Site (‘Open Redirect’) Description: CWE-601 is a vulnerability that occurs when a web application allows an attacker to redirect a user to an untrusted website. CSRF via Flash attacks can exploit open redirects to trick users into performing actions on a malicious site. Link: 

CWE-602: Client-Side Enforcement of Server-Side Security Description: CWE-602 refers to weaknesses that occur when security controls are implemented on the client-side rather than the server-side. CSRF via Flash attacks can bypass client-side security controls to perform unauthorized actions on a web application. 

CWE-611: Improper Restriction of XML External Entity Reference Description: CWE-611 is a vulnerability that occurs when an application does not properly validate and restrict external XML entity references. CSRF via Flash attacks can exploit improper XML external entity reference handling to access sensitive information or perform unauthorized actions. 

CWE-798: Use of Hard-coded Credentials Description: CWE-798 refers to vulnerabilities that occur when applications use hard-coded credentials, such as passwords or API keys. CSRF via Flash attacks can exploit hard-coded credentials to perform unauthorized actions on a web application. 

CWE-807: Reliance on Untrusted Inputs in a Security Decision Description: CWE-807 is a weakness that occurs when an application relies on untrusted inputs to make security decisions. CSRF via Flash attacks can exploit this weakness to perform unauthorized actions on a web application. 

CWE-829: Inclusion of Functionality from Untrusted Control Sphere Description: CWE-829 is a vulnerability that occurs when an application includes functionality from an untrusted source, such as a third-party library or plugin. CSRF via Flash attacks can exploit this weakness to perform unauthorized actions on a web application. 

CWE-918: Server-Side Request Forgery (SSRF) Description: CWE-918 is a vulnerability that occurs when an application allows an attacker to make HTTP requests from the server-side. CSRF via Flash attacks can exploit SSRF vulnerabilities to perform unauthorized actions on a web application. 

TOP 10 CVE for Cross-Site Request Forgery (CSRF) via Flash

CVE-2021-28053: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the June 2021 security update for Flash Player. 

CVE-2021-21017: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the January 2021 security update for Flash Player. 

CVE-2020-9746: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the August 2020 security update for Flash Player. 

CVE-2019-7845: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the February 2019 security update for Flash Player. 

CVE-2018-4878: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the February 2018 security update for Flash Player. 

CVE-2017-3085: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the April 2017 security update for Flash Player. 

CVE-2016-1019: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the April 2016 security update for Flash Player. 

CVE-2015-8651: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the December 2015 security update for Flash Player. 

CVE-2014-9163: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the December 2014 security update for Flash Player. 

CVE-2013-0630: A vulnerability in Adobe Flash Player allowed attackers to execute arbitrary code on a target system by convincing a user to visit a specially crafted website. This vulnerability was fixed in the February 2013 security update for Flash Player. 

General methodology and checklist for Cross-Site Request Forgery (CSRF) via Flash

Here is a general methodology and checklist for pentesters, hackers, and developers for identifying and mitigating Cross-Site Request Forgery (CSRF) via Flash:

  1. Identify potentially vulnerable pages: Start by identifying pages where CSRF vulnerabilities may exist. These pages usually involve user input and perform sensitive actions, such as changing user settings or making purchases.

  2. Analyze the HTML and JavaScript: Analyze the HTML and JavaScript code for potential vulnerabilities. Look for form elements that do not have anti-CSRF tokens, hidden forms, or any Flash elements that may be vulnerable.

  3. Test for CSRF vulnerabilities: Attempt to perform CSRF attacks on the identified vulnerable pages. This can be done using tools such as Burp Suite, OWASP ZAP, or manually by crafting HTTP requests and sending them through various channels.

  4. Identify potential attack vectors: Identify potential attack vectors that can be used to exploit the CSRF vulnerability, such as email phishing or malicious websites.

  5. Develop and implement countermeasures: Develop and implement countermeasures to mitigate the CSRF vulnerability. These countermeasures can include implementing anti-CSRF tokens, using HTTP-only cookies, or disabling Flash content.

  6. Test the countermeasures: Test the effectiveness of the implemented countermeasures by attempting to perform CSRF attacks and verifying that they are blocked.

  7. Document and report: Document the findings, including the vulnerable pages and any mitigations implemented, and report them to the relevant parties.

Tips and guides:

Follow industry best practices for web application security, such as the OWASP Top 10.

Stay up-to-date with the latest security vulnerabilities and patches, including those related to Flash.

Use security testing tools to automate and streamline the testing process.

Use only legal and ethical means for testing and exploiting vulnerabilities.

Share findings and recommendations with relevant parties in a clear and actionable manner.

Automated and manual tools for exploiting Cross-Site Request Forgery (CSRF) via Flash

  1. BeEF (Browser Exploitation Framework): BeEF is a penetration testing tool that can be used for exploiting CSRF vulnerabilities via Flash. It allows attackers to control a victim’s browser and execute commands on their behalf.

  2. Burp Suite: Burp Suite is a web application security testing tool that can be used for both automated and manual testing. It includes a range of features for identifying and exploiting CSRF vulnerabilities, including a CSRF PoC generator.

  3. OWASP ZAP (Zed Attack Proxy): OWASP ZAP is a free, open-source security testing tool that can be used for finding and exploiting CSRF vulnerabilities. It includes a range of features for identifying vulnerabilities, including a CSRF scanner.

  4. Fiddler: Fiddler is a web debugging tool that can be used for testing and analyzing web applications. It includes a range of features for identifying and exploiting CSRF vulnerabilities, including a CSRF PoC generator.

  5. Chrome Developer Tools: Chrome Developer Tools is a built-in feature in the Google Chrome browser that can be used for analyzing and debugging web applications. It includes a range of features for identifying and exploiting CSRF vulnerabilities, including the ability to modify HTTP requests.

  6. Wireshark: Wireshark is a network protocol analyzer that can be used for capturing and analyzing network traffic. It can be used for identifying and exploiting CSRF vulnerabilities by analyzing the HTTP requests and responses.

  7. HTTP Requester: HTTP Requester is a free, open-source tool that can be used for manually testing HTTP requests. It includes a range of features for crafting and sending custom HTTP requests, which can be used to test for CSRF vulnerabilities.

  8. CSRF Tester: CSRF Tester is a free, open-source tool that can be used for testing CSRF vulnerabilities. It includes a range of features for identifying and exploiting vulnerabilities, including a CSRF PoC generator.

  9. Selenium: Selenium is an open-source web testing tool that can be used for automating browser-based testing. It can be used for identifying and exploiting CSRF vulnerabilities by automating the process of crafting and sending HTTP requests.

  10. Tamper Data: Tamper Data is a free, open-source Firefox extension that can be used for analyzing and modifying HTTP requests. It can be used for identifying and exploiting CSRF vulnerabilities by modifying HTTP requests on-the-fly.

How user can be protected from Cross-Site Request Forgery (CSRF) via Flash

  1. Keep your browser and mobile device up to date with the latest security updates and patches.

  2. Disable or limit the use of Adobe Flash on your browser or mobile device.

  3. Use a reputable antivirus or antimalware program that can detect and block CSRF attacks.

  4. Avoid clicking on suspicious links or downloading unknown files.

  5. Use a unique and strong password for each account and enable two-factor authentication whenever possible.

  6. Be cautious when entering sensitive information, such as credit card numbers or personal information, on websites or mobile apps.

  7. Use a VPN or proxy service to hide your IP address and encrypt your online activity.

  8. Regularly review your account activity and log out of accounts when you are finished using them.

By following these simple steps, users can significantly reduce their risk of falling victim to CSRF attacks via Flash. It’s important to note that while these measures can help protect users, it’s ultimately the responsibility of web developers and mobile app developers to implement security measures that prevent these types of attacks.

How companies and its developers can prevent Cross-Site Request Forgery (CSRF) via Flash

Use anti-CSRF tokens: This involves generating and validating unique tokens for each session or transaction. The token is included in each request sent from the client to the server and verified by the server to ensure that the request is legitimate.

Use SameSite cookies: SameSite cookies prevent the browser from sending cookies in cross-site requests, which can help prevent CSRF attacks.

Use Content Security Policy (CSP): CSP is a security mechanism that allows web developers to specify which sources of content are allowed to be loaded on a web page. It can be used to prevent the execution of malicious scripts and prevent CSRF attacks.

Limit the use of Adobe Flash: Adobe Flash is a common tool used in CSRF attacks. Limiting or disabling the use of Flash can help prevent these types of attacks.

Implement secure coding practices: Developers should follow secure coding practices such as input validation, output encoding, and proper error handling to prevent vulnerabilities that can be exploited by CSRF attacks.

Conduct regular security audits and penetration testing: Regular security audits and penetration testing can help identify vulnerabilities in web applications and mobile apps, including CSRF vulnerabilities.

Keep software and systems up to date: Keeping software and systems up to date with the latest security updates and patches can help prevent known vulnerabilities from being exploited.

Books with review of Cross-Site Request Forgery (CSRF) via Flash

Unfortunately, there are not many books specifically focused on Cross-Site Request Forgery (CSRF) via Flash. However, here are some books on web application security that cover CSRF attacks and related topics:

“The Web Application Hacker’s Handbook: Finding and Exploiting Security Flaws” by Dafydd Stuttard and Marcus Pinto (2007) – This book provides a comprehensive guide to web application security, including detailed information on CSRF attacks and other common vulnerabilities.

“OWASP Testing Guide v4.1” by OWASP (2021) – The OWASP Testing Guide is a comprehensive guide to testing web applications for security vulnerabilities, including CSRF attacks.

“Web Security for Developers: Real Threats, Practical Defense” by Malcolm McDonald (2020) – This book provides practical guidance on securing web applications, including an overview of CSRF attacks and mitigation strategies.

“The Tangled Web: A Guide to Securing Modern Web Applications” by Michal Zalewski (2012) – This book covers a wide range of web application security topics, including CSRF attacks and other related attacks.

“Black Hat Python: Python Programming for Hackers and Pentesters” by Justin Seitz (2014) – While not specifically focused on CSRF attacks, this book provides practical guidance on using Python for web application security testing and exploitation, which may include CSRF attacks.

Useful resources for education

OWASP Cross-Site Request Forgery Prevention Cheat Sheet: This is a comprehensive guide by OWASP that provides detailed information on how to prevent Cross-Site Request Forgery attacks. It includes explanations of different types of CSRF attacks and methods to mitigate them, such as the use of anti-CSRF tokens.  

PortSwigger Web Security Academy: This online resource provides free interactive courses on web security, including a dedicated section on Cross-Site Request Forgery. The courses cover how CSRF attacks work and how to prevent them using different techniques. 

CSRFTester: This is an open-source tool for testing web applications for Cross-Site Request Forgery vulnerabilities. It includes both manual and automated testing features and can be used for educational and testing purposes. 

Burp Suite: This is a popular web application security testing tool that includes a dedicated module for detecting and exploiting CSRF vulnerabilities. It can be used for both manual and automated testing of web applications. 

Web Security Dojo: This is a free open-source virtual machine that includes multiple web security tools, including tools for detecting and exploiting CSRF vulnerabilities. It can be used for educational and testing purposes to learn about web security and practice exploiting vulnerabilities in a safe environment.  

Conclusion 

It is critical for developers and organizations to take steps to prevent CSRF attacks by implementing effective mitigation strategies, such as using anti-CSRF tokens, ensuring secure coding practices, and staying up-to-date with the latest security patches and updates. Additionally, users can take steps to protect themselves by being cautious of clicking on suspicious links or downloading unknown software. Overall, awareness and proactive measures are key in protecting against CSRF attacks and maintaining strong cybersecurity practices.

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