MooTools Regular Expression Denial of Service in mootools

Background

MooTools is a collection of JavaScript utilities for JavaScript developers. It provides various functionalities and tools to simplify JavaScript development. One of the features included in MooTools is a CSS selector parser. This parser is used to parse and process CSS selectors in JavaScript applications. However, all known versions of MooTools are vulnerable to a Regular Expression Denial of Service (ReDoS) attack. This vulnerability can be exploited when an attacker is able to inject a malicious string into a CSS selector at runtime. This type of injection is common with libraries like jQuery that use CSS selectors. Unfortunately, there are no available patches to address this vulnerability at the moment.

Vulnerability Detail

The vulnerability in MooTools arises from a weakness in the CSS selector parser. The parser is susceptible to Regular Expression Denial of Service (ReDoS) attacks, which can lead to denial of service or performance degradation. An attacker can exploit this vulnerability by injecting a specially crafted string into a CSS selector, causing the parser to enter into an inefficient matching state. This can result in excessive CPU usage and potentially render the application unresponsive. The impact of this vulnerability can be severe, especially in scenarios where user input is used directly in CSS selectors.

Workaround

As there are no available patches for this vulnerability, a possible workaround is to implement input validation and sanitization measures. By carefully validating and sanitizing user input before using it in CSS selectors, the risk of injection attacks can be mitigated. Here is an example of how input validation can be performed in JavaScript:

function sanitizeInput(input) {
  // Perform input validation and sanitization
  // ... 
  return sanitizedInput;
}

var userInput = getUserInput();
var sanitizedInput = sanitizeInput(userInput);

// Use the sanitized input in CSS selectors
var selector = '.class-' + sanitizedInput;
// ... 

Conclusion

The MooTools library, used by JavaScript developers, is vulnerable to a Regular Expression Denial of Service (ReDoS) attack. This vulnerability can be exploited by injecting a malicious string into a CSS selector, potentially leading to denial of service or performance degradation. While no patches are currently available, it is crucial to stay informed about updates and implement input validation and sanitization measures to mitigate the risk. For further support on vulnerability remediation, you can reach out to DevNack.com.

See every vulnerability recorded for mootools →

FAQ