What is CVE-2020-11023?
CVE-2020-11023 is a security vulnerability in jQuery, one of the most widely used JavaScript libraries on the web. This vulnerability allows an attacker to perform Cross-Site Scripting (XSS) attacks by manipulating the content that is passed to jQuery’s htmlPrefilter function. It affects jQuery versions prior to 3.5.0, making it a significant risk for web applications that rely on older versions of this library.
CVSS Score and Severity
- CVSS Score: 6.1 (Medium)
- Severity: The CVSS score of 6.1 out of 10 indicates a medium severity level, reflecting the potential for XSS attacks that could compromise the security of web applications, especially those with user-generated content.
So what’s the problem?
The problem with CVE-2020-11023 lies in its potential to allow XSS attacks, where an attacker can inject malicious scripts into a web page viewed by other users. This can lead to the execution of arbitrary JavaScript code in the context of the affected site, allowing attackers to steal session cookies, redirect users to malicious sites, or perform other malicious activities. Since jQuery is used in millions of websites worldwide, the vulnerability poses a widespread risk, especially for applications that handle sensitive user data.
Background and Context
Background on the vulnerability
CVE-2020-11023 was discovered during a security review of the jQuery library in 2020. jQuery is a foundational tool in modern web development, simplifying tasks like DOM manipulation, event handling, and AJAX requests. The vulnerability is rooted in the htmlPrefilter function, which is responsible for sanitizing HTML content passed to jQuery. Due to insufficient sanitization, it was possible for attackers to inject malicious scripts that could be executed within the context of the web page, leading to XSS attacks.
Description of the Vulnerability (CVE-2020-11023)
The vulnerability occurs because jQuery’s htmlPrefilter function did not properly sanitize certain HTML tags and attributes before inserting them into the DOM. This oversight allowed attackers to craft payloads that could bypass the intended security mechanisms and inject arbitrary scripts into web pages. The vulnerability is particularly dangerous in scenarios where user input is dynamically inserted into the HTML content of a page without proper validation or escaping.
Root Cause Analysis
The root cause of CVE-2020-11023 is the improper handling of HTML content by the htmlPrefilter function in jQuery. Specifically, the function failed to adequately sanitize certain elements and attributes that could be used to inject scripts. This flaw in input handling is a common issue in web applications where user input is processed and rendered without sufficient security checks.
Impact and Exploitation
The impact of CVE-2020-11023
Exploiting CVE-2020-11023 can have several serious impacts:
- Cross-Site Scripting (XSS): The primary impact is the potential for XSS attacks, where an attacker can inject and execute malicious scripts in the context of the affected website. This can lead to unauthorized actions, data theft, or further compromise of the web application.
- Data Breach: If exploited, this vulnerability could allow attackers to steal sensitive information such as session tokens, login credentials, or personal data, leading to a data breach.
- User Trust: XSS attacks can undermine user trust in a website, especially if the site is used to serve malicious content to users or redirect them to phishing sites.
Exploit
To exploit CVE-2020-11023, an attacker needs to identify a web application that uses a vulnerable version of jQuery and processes user input through the htmlPrefilter function. The exploitation process involves:
- Crafting a payload that includes malicious HTML or JavaScript code designed to bypass the insufficient sanitization.
- Injecting this payload into a field or input that the vulnerable web application processes using jQuery.
- When the vulnerable jQuery code executes, the malicious script is injected into the web page and executed in the context of users viewing the page.
In-the-Wild Attacks
There have been instances of CVE-2020-11023 being exploited in the wild, particularly in scenarios where web applications failed to update their jQuery libraries. Attackers have leveraged this vulnerability to conduct XSS attacks, targeting sites with user-generated content or dynamic content insertion, such as forums, comment sections, and content management systems.
Vulnerable code/package in the application
The vulnerable code is located within the htmlPrefilter function in jQuery versions prior to 3.5.0. This function is responsible for preparing HTML content for insertion into the DOM. Due to insufficient sanitization of certain HTML elements and attributes, this function allowed for the injection of malicious scripts, leading to potential XSS attacks.
Statistics on vulnerability
Given the widespread use of jQuery, the potential impact of CVE-2020-11023 is significant. While specific exploitation statistics are not readily available, it is estimated that a large number of web applications, especially those built before 2020, may still be using vulnerable versions of jQuery, making them susceptible to this vulnerability.
Mitigation and Remediation
Mitigating CVE-2020-11023
Organizations and developers can mitigate the risks associated with CVE-2020-11023 by:
- Updating jQuery: The most effective mitigation is to update jQuery to version 3.5.0 or later, where this vulnerability has been patched. The update ensures that HTML content is properly sanitized before being inserted into the DOM.
- Input Validation and Sanitization: Implement strong input validation and sanitization practices to ensure that user-generated content is thoroughly checked before being processed by the web application.
- Content Security Policy (CSP): Implementing a robust Content Security Policy can help prevent the execution of unauthorized scripts, even if an XSS vulnerability exists.
Patch and Bypass: Fixes Added for CVE-2020-11023
The patch for CVE-2020-11023 involves changes to the htmlPrefilter function in jQuery, ensuring that it correctly sanitizes HTML content and removes potential XSS vectors. Organizations should ensure that their web applications are updated to use jQuery 3.5.0 or later to protect against this vulnerability.
Proactive response
A proactive security approach includes regularly updating web application libraries, conducting security audits of web applications, and ensuring that all input handling and rendering processes are secure. Developers should also be educated on secure coding practices, particularly in relation to XSS prevention.
Proof of Concept (POC)
A POC for CVE-2020-11023 involves injecting a script via unsanitized HTML attributes. For example, using jQuery with the vulnerable htmlPrefilter function:
$('div').html('<img src="x" onerror="alert(1)">');This code injects an image tag with an onerror event that triggers an alert, demonstrating the XSS vulnerability.
Real-world Impact and Response
Timeline/changelog
- April 2020: Discovery of CVE-2020-11023 during a security review of jQuery.
- April 2020: Public disclosure of the vulnerability and release of jQuery version 3.5.0, which includes the fix.
- May 2020: Continued advisories and recommendations for web developers to update their jQuery libraries.
- June 2020: Monitoring for potential exploitation and providing additional guidance on secure web development practices.
Observed Activity
Since the disclosure of CVE-2020-11023, there have been reports of its exploitation in the wild, particularly in older web applications that have not been updated to the latest version of jQuery. Attackers have used this vulnerability to inject malicious scripts into vulnerable websites, leading to XSS attacks and the compromise of user data.
Mass Scanning
There have been no widespread reports of mass scanning specifically targeting CVE-2020-11023. However, given the nature of XSS vulnerabilities, attackers often use automated tools to scan for vulnerable websites, especially those running outdated versions of popular libraries like jQuery.
Vulnerable Server Discovery
Vulnerable web applications can be discovered through targeted scanning or by analyzing web pages for signs of outdated jQuery versions. Attackers often look for websites that display version information in their source code or that exhibit behaviors indicative of using older, vulnerable libraries.
Reasoning and Scoring
Corporate networks impacted globally
CVE-2020-11023 has the potential to impact corporate networks globally, particularly in industries that heavily rely on web applications for their operations. The vulnerability can be exploited to conduct XSS attacks, leading to data breaches, defacement, or further compromise of corporate web assets.
Corporate numbers impacted by countries
- United States: Widespread use of jQuery in enterprise web applications, with many organizations at risk.
- Europe: Significant adoption of jQuery in financial and e-commerce sectors, leading to potential exposure.
- Asia: Extensive use of jQuery in technology and service industries, where secure web operations are critical.
Conclusion
Who should be paying attention to this?
Web developers, cybersecurity professionals, and organizations that rely on jQuery for web application development should prioritize attention to CVE-2020-11023. Ensuring that web applications are secure is critical for maintaining the overall trust and integrity of online services.
Who is exploiting it and how?
CVE-2020-11023 has been exploited by attackers who identify web applications using vulnerable versions of jQuery. These attackers craft malicious payloads designed to exploit the insufficient sanitization in the htmlPrefilter function, leading to XSS attacks that can compromise the affected site and its users.
How are things likely to develop?
As more web applications update their jQuery versions, the risk of exploitation decreases. However, websites that remain unpatched are still vulnerable to XSS attacks. Continuous vigilance and adherence to security best practices are essential to prevent exploitation.
How long has it been around?
CVE-2020-11023 was discovered and disclosed in April 2020, but the underlying issue in jQuery’s htmlPrefilter function may have existed for years before its discovery. This highlights the importance of regular updates and security reviews for widely used libraries like jQuery.
