CVE-2021-24426 in Backup by 10Web Plugin
Summary
by MITRE • 07/13/2021
The Backup by 10Web – Backup and Restore Plugin WordPress plugin through 1.0.20 does not sanitise or escape the tab parameter before outputting it back in the page, leading to a reflected Cross-Site Scripting issue
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 07/15/2021
The vulnerability identified as CVE-2021-24426 affects the Backup by 10Web WordPress plugin version 1.0.20 and earlier, presenting a reflected cross-site scripting vulnerability that arises from improper input sanitization. This issue manifests when the plugin fails to adequately sanitize or escape the tab parameter before incorporating it back into the HTML output of the web page. The vulnerability exists within the plugin's handling of user-supplied input, specifically targeting the tab parameter that is typically used for navigation within the plugin's administrative interface. The reflected nature of this XSS vulnerability means that an attacker can craft a malicious URL containing crafted script code within the tab parameter, which when executed by a victim's browser, will result in the execution of malicious scripts in the context of the victim's session. This type of vulnerability falls under the CWE-79 category of Cross-Site Scripting, specifically categorized as reflected XSS where the malicious script is reflected off the web server back to the victim's browser. The vulnerability is particularly concerning in the context of WordPress plugins as it can be exploited to hijack user sessions, steal sensitive information, or perform unauthorized actions on behalf of authenticated users within the WordPress administration panel.
The technical flaw in this vulnerability stems from the plugin's improper handling of user input within the administrative interface. When users navigate through the plugin's various tabs, the tab parameter is passed through the URL and directly incorporated into the HTML output without proper sanitization or escaping mechanisms. This allows attackers to inject malicious JavaScript code that gets executed in the victim's browser when the page loads. The vulnerability is particularly dangerous because it requires no authentication to exploit, as the reflected XSS occurs in the context of the victim's own browser session with the plugin's administrative interface. The lack of input validation and output escaping creates an environment where malicious scripts can be executed with the privileges of the authenticated user, potentially leading to full compromise of the WordPress installation. This vulnerability aligns with ATT&CK technique T1566.001 which involves the use of malicious links to deliver payloads to targets, and specifically demonstrates how a web application vulnerability can be exploited to achieve initial access or privilege escalation.
The operational impact of this vulnerability extends beyond simple script execution, as it can be leveraged for more sophisticated attacks within the WordPress environment. An attacker could craft malicious URLs that, when clicked by an administrator, would execute scripts designed to steal session cookies, modify plugin settings, or even install additional malicious plugins. The reflected nature of the vulnerability means that the attack vector is typically through phishing emails, social engineering campaigns, or compromised websites that direct users to malicious URLs. The vulnerability's exploitation requires minimal technical knowledge, making it particularly dangerous as it can be used by attackers with limited expertise in web application security. Organizations running vulnerable versions of the Backup by 10Web plugin are at risk of having their administrative interfaces compromised, potentially leading to complete takeover of WordPress installations. The impact is amplified when considering that WordPress administrators often have elevated privileges and access to sensitive data, making the compromise of their sessions particularly damaging. This vulnerability also demonstrates the importance of proper input validation and output escaping in web applications, as the simple omission of these security measures can lead to significant security breaches. The vulnerability's classification as a reflected XSS aligns with ATT&CK technique T1203 which involves the use of web-based attacks to gain access to systems, and represents a common attack pattern that has been documented in numerous web application security incidents throughout the industry.
The recommended mitigations for this vulnerability include immediate upgrading to a patched version of the Backup by 10Web plugin, as the vendor has likely released a security update addressing the sanitization issue. Organizations should also implement proper input validation and output escaping mechanisms throughout their WordPress installations, ensuring that all user-supplied parameters are properly sanitized before being incorporated into HTML output. The implementation of Content Security Policy headers can provide additional protection against XSS attacks by restricting the sources from which scripts can be loaded. Regular security auditing of WordPress plugins and themes should be conducted to identify and remediate similar vulnerabilities. Additionally, administrators should consider implementing web application firewalls that can detect and block malicious requests containing XSS payloads. The vulnerability serves as a reminder of the critical importance of proper input validation and output escaping in preventing cross-site scripting attacks, and demonstrates how seemingly minor oversights in code can lead to significant security implications. Organizations should also maintain updated threat intelligence feeds to stay informed about similar vulnerabilities in their WordPress ecosystem and ensure that their security measures are comprehensive and up-to-date with current threat landscape requirements.