CVE-2017-18563 in rsvp Plugin
Summary
by MITRE
The rsvp plugin before 2.3.8 for WordPress has persistent XSS via the note field on the attendee-list screen.
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Analysis
by VulDB Data Team • 11/28/2023
The CVE-2017-18563 vulnerability represents a critical persistent cross-site scripting flaw within the RSVP plugin for WordPress systems. This vulnerability specifically affects versions prior to 2.3.8 and resides within the attendee-list screen functionality where users can input notes about event attendees. The flaw allows malicious actors to inject persistent XSS payloads through the note field, which can then be executed whenever other users view the attendee list. This type of vulnerability falls under CWE-79 - Cross-site Scripting, which is classified as a fundamental web application security weakness that enables attackers to inject client-side scripts into web pages viewed by other users.
The technical exploitation of this vulnerability occurs when an attacker submits a malicious script within the note field of an attendee entry. When legitimate users navigate to the attendee list screen, their browsers execute the injected script within the context of the vulnerable WordPress installation. This persistent nature means the malicious code remains active and executable each time the page loads, potentially allowing attackers to steal session cookies, redirect users to malicious sites, or perform actions on behalf of authenticated users. The vulnerability specifically targets the rsvp plugin's handling of user input without proper sanitization or output encoding, creating an attack surface where untrusted data flows directly into the web page context.
The operational impact of CVE-2017-18563 extends beyond simple script execution as it can enable sophisticated attack chains within WordPress environments. Attackers can leverage this vulnerability to escalate privileges, steal administrative credentials, or establish persistent backdoors within the WordPress installation. The vulnerability affects any WordPress site utilizing the rsvp plugin with affected versions, potentially compromising entire websites if administrators or users with sufficient privileges view the attendee list. This represents a significant risk in enterprise environments where event management systems may contain sensitive attendee information and where the rsvp plugin is commonly used for managing guest lists and event participation tracking. The vulnerability can be exploited through social engineering tactics where attackers convince event organizers to input malicious payloads into the note fields, making it particularly dangerous due to its low detection rate.
Mitigation strategies for CVE-2017-18563 primarily focus on immediate plugin updates to version 2.3.8 or later, which contain proper input sanitization and output encoding mechanisms. Organizations should implement comprehensive input validation that strips or encodes potentially dangerous characters such as script tags, event handlers, and javascript protocols from user-supplied content. The implementation of Content Security Policy headers can provide additional defense-in-depth measures by restricting script execution and preventing unauthorized code injection. Security monitoring should include regular scanning for vulnerable plugin versions and monitoring of attendee list access patterns for suspicious activity. This vulnerability aligns with ATT&CK technique T1059.005 - Command and Scripting Interpreter: Visual Basic, which covers scripting language-based attacks, and T1566.002 - Phishing: Spearphishing Attachment, as the attack often begins with social engineering to manipulate users into submitting malicious content. Organizations should also consider implementing web application firewalls to detect and block common XSS payload patterns and establish regular security audits to identify similar vulnerabilities in other plugins or custom code components.