CVE-2023-26445: Protecting against JavaScript Object Notation Language Object-Based (JSLOB) theme settings exploitation in frontend themes

A newly discovered vulnerability, CVE-2023-26445, allows attackers to exploit frontend themes by manipulating user-controllable JSLOB settings, possibly leading to session hijacking, unwanted actions on web interfaces, and API abuses. This post provides insight into the vulnerability, what it is, how it can be exploited, and how to mitigate potential risks. Moreover, it includes a code snippet and links to original references, helping developers and users understand and address the CVE-2023-26445 issue in their platforms effectively.

CVE-2023-26445 Exploit Details

The vulnerability arises from frontend themes being defined by user-controllable JSLOB settings, which may contain a link to a malicious resource. During the user's login process, this resource would be processed, potentially leading to the execution of malicious script code within the victim's context.

To exploit this vulnerability, an attacker would need temporary access to a user's account or deceive a user into visiting a compromised account. By making unauthorized modifications to the JSLOB settings, the attacker could potentially hijack a user's session or trigger unwanted actions via the web interface and API.

Although no public exploits for CVE-2023-26445 have been found, it is essential for users and developers to protect themselves against this vulnerability to prevent any future attacks or malicious uses.

Mitigating Risks

To mitigate the risks associated with CVE-2023-26445, we suggest implementing a sanitization measure for theme values to ensure that only safe resources are utilized. Additionally, a default fallback theme should be provided in cases where no theme matches or a user's theme is invalid.

Here is an example of implementing this mitigation in your frontend theme settings

function sanitizeThemeValue(theme) {
  const allowedThemes = ['themeA', 'themeB', 'themeC'];
  return allowedThemes.includes(theme) ? theme : 'defaultTheme';
}

function setTheme(theme) {
  const sanitizedTheme = sanitizeThemeValue(theme);
  // process and apply the theme here
}

This code snippet includes a simple function sanitizeThemeValue that checks if the provided theme value is included in an array of allowed themes. If it is not found, the default theme will be used. This way, malicious resources are prevented from being processed during the login sequence.

You can consult the official sources and discussions regarding CVE-2023-26445 at the following links

1. CVE List (MITRE)
2. National Vulnerability Database (NVD)

Conclusion

CVE-2023-26445 is a vulnerability that affects frontend themes, potentially putting user accounts at risk of malicious exploitation. It allows attackers to run unauthorized script code within a victim's context, leading to session hijacking and unwanted actions via web interfaces or APIs. To adequately protect your platform and users against this vulnerability, follow the provided code snippet and mitigation strategy: sanitize user-provided theme values and offer a default fallback, ensuring only trusted resources are processed during login. Stay vigilant and stay safe.

Timeline

Published on: 08/02/2023 13:15:00 UTC
Last modified on: 08/07/2023 18:19:00 UTC