CVE-2021-24980 in Gwolle Guestbook Plugin
Summary
by MITRE • 12/27/2021
The Gwolle Guestbook WordPress plugin before 4.2.0 does not sanitise and escape the gwolle_gb_user_email parameter before outputting it back in an attribute, leading to a Reflected Cross-Site Scripting issue in an admin page
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 12/31/2021
The vulnerability identified as CVE-2021-24980 affects the Gwolle Guestbook WordPress plugin version 4.2.0 and earlier, representing a critical reflected cross-site scripting flaw that specifically targets administrator interfaces. This issue stems from insufficient input validation and output escaping mechanisms within the plugin's codebase, creating a security exposure that can be exploited by malicious actors to inject malicious scripts into admin pages. The vulnerability manifests when the plugin fails to properly sanitise the gwolle_gb_user_email parameter before incorporating it into HTML attributes, thereby allowing attackers to execute arbitrary JavaScript code within the context of an administrator's browser session. The flaw is particularly concerning because it operates within admin pages where privileged users are likely to interact with the plugin's functionality, potentially enabling attackers to escalate their privileges or compromise the entire WordPress installation.
The technical exploitation of this vulnerability occurs through the manipulation of the gwolle_gb_user_email parameter, which is typically passed through HTTP request parameters to the plugin's administrative interface. When an administrator visits a page that processes this parameter without proper sanitisation, the malicious payload embedded within the email parameter gets executed in the browser context of the authenticated user. This reflected XSS vulnerability falls under the CWE-79 category, which specifically addresses Cross-Site Scripting flaws in software applications. The attack vector requires the administrator to be tricked into clicking on a malicious link containing the crafted payload, making social engineering a critical component of successful exploitation. The vulnerability is particularly dangerous because it targets the administrative interface where users have elevated privileges, potentially allowing attackers to gain unauthorized access to sensitive administrative functions.
The operational impact of CVE-2021-24980 extends beyond simple script execution, as it can enable attackers to perform a wide range of malicious activities within the compromised administrative session. Attackers can leverage this vulnerability to steal administrator session cookies, redirect users to malicious websites, modify plugin configurations, or even install malware within the WordPress environment. The reflected nature of the vulnerability means that the malicious script is not stored on the server but rather injected through a maliciously crafted URL, making detection more challenging for security monitoring systems. This type of vulnerability can also serve as a stepping stone for more sophisticated attacks, including privilege escalation, data exfiltration, or the establishment of persistent backdoors within the WordPress installation. The impact is particularly severe in environments where the guestbook plugin is widely used and administrators frequently interact with its administrative features.
Mitigation strategies for CVE-2021-24980 primarily focus on immediate plugin updates to version 4.2.0 or later, which contain the necessary sanitisation and escaping mechanisms to prevent the reflected XSS vulnerability. Administrators should also implement additional security measures including input validation at multiple layers, output escaping for all dynamic content, and regular security audits of installed plugins. The implementation of Content Security Policy headers can provide an additional layer of protection against XSS attacks by restricting the sources from which scripts can be loaded. Security monitoring should include the detection of suspicious parameter values in administrative interfaces, and administrators should be trained to recognise social engineering attempts that might exploit this vulnerability. Organizations should also consider implementing web application firewalls to detect and block malicious requests targeting known XSS patterns. The ATT&CK framework categorizes this vulnerability under the T1059.007 technique for 'Scripting' and T1566 for 'Phishing', highlighting the multi-faceted approach required for both exploitation and defense against such attacks. Regular security assessments and maintaining updated security practices are essential for preventing exploitation of this type of vulnerability in WordPress environments.