Cross-site Scripting (XSS)

Affecting jquery package, versions <1.9.0 >=1.7.1

medium severity

Overview

jquery is JavaScript library for DOM operations.

Affected versions of the package are vulnerable to Cross-site Scripting (XSS) attacks. The jQuery(strInput) function does not differentiate selectors from HTML in a reliable fashion. In the vulnerable version, jQuery determined whether the input was HTML or not by looking for the '<' character anywhere in the string, giving attackers more flexibility when attempting to construct malicious payload.

In the fixed versions, jQuery only deems the input to be HTML if it explicitly starts with '<', limiting exploitability only to attackers who can control the beginning of a string, which is far less common.

Details

Cross-Site Scripting (XSS) attacks occur when an attacker tricks a user’s browser to execute malicious JavaScript code in the context of a victim’s domain. Such scripts can steal the user’s session cookies for the domain, scrape or modify its content, and perform or modify actions on the user’s behalf, actions typically blocked by the browser’s Same Origin Policy.

These attacks are possible by escaping the context of the web application and injecting malicious scripts in an otherwise trusted website. These scripts can introduce additional attributes (say, a "new" option in a dropdown list or a new link to a malicious site) and can potentially execute code on the clients side, unbeknown to the victim. This occurs when characters like < > " ' are not escaped properly.

There are a few types of XSS:

  • Persistent XSS is an attack in which the malicious code persists into the web app’s database.
  • Reflected XSS is an which the website echoes back a portion of the request. The attacker needs to trick the user into clicking a malicious link (for instance through a phishing email or malicious JS on another page), which triggers the XSS attack.
  • DOM-based XSS is an that occurs purely in the browser when client-side JavaScript echoes back a portion of the URL onto the page. DOM-Based XSS is notoriously hard to detect, as the server never gets a chance to see the attack taking place.

Remediation

Upgrade jquery to version 1.9.0 or higher.

References

Do your applications use this vulnerable package?

Credit
Richard Gibson
CVE
CVE-2012-6708 CVE-2017-16011
CWE
CWE-79
Snyk ID
npm:jquery:20120206
Disclosed
19 Jun, 2012
Published
20 Oct, 2016