Source: contact@wpscan.com
The Logo Slider WordPress plugin before 4.9.0 does not validate and escape some of its slider options before outputting them back in the dashboard, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks.
Stored Cross-Site Scripting (XSS) vulnerabilities exist in the Logo Slider WordPress plugin, allowing attackers with contributor-level access to inject malicious JavaScript into the website. This can lead to account hijacking, data theft, and website defacement, severely impacting the website's integrity and user trust.
Step 1: Payload Delivery: An attacker with contributor-level access logs into the WordPress dashboard and navigates to the Logo Slider plugin's settings or configuration options.
Step 2: Payload Injection: The attacker crafts a malicious JavaScript payload (e.g., <script>alert('XSS');</script> or more sophisticated code for session hijacking) and inserts it into a vulnerable slider option field, such as the slider title, description, or a custom CSS field.
Step 3: Payload Storage: The attacker saves the modified slider options, which stores the malicious JavaScript payload in the WordPress database.
Step 4: Payload Execution: When an administrator or other user with sufficient privileges views the WordPress dashboard (e.g., the plugin's settings page or a page displaying the slider), the plugin retrieves the stored slider options from the database.
Step 5: XSS Trigger: The plugin fails to properly sanitize or escape the attacker's injected JavaScript when rendering the slider options in the dashboard. This causes the malicious JavaScript to execute in the administrator's browser.
Step 6: Attack Impact: The executed JavaScript allows the attacker to perform actions such as stealing the administrator's session cookies, redirecting the administrator to a phishing site, or modifying the website's content.
The vulnerability stems from insufficient input validation and output escaping within the Logo Slider plugin's administrative interface. Specifically, the plugin fails to properly sanitize user-supplied input for slider options before storing and displaying them in the WordPress dashboard. This allows attackers to inject malicious JavaScript code into these options. When an administrator or other privileged user views the dashboard, the injected JavaScript executes in their browser, leading to the compromise. The root cause is a missing or inadequate implementation of input validation and output encoding (e.g., HTML escaping) for user-provided data within the plugin's settings.
While no specific APTs are directly linked to this CVE at this time, the nature of the vulnerability makes it attractive to a wide range of attackers, including those seeking to deface websites, steal user credentials, or distribute malware. This vulnerability is not currently listed on the CISA KEV.
Monitor web server logs for suspicious activity, such as unusual POST requests to the plugin's configuration endpoints containing potentially malicious JavaScript payloads.
Implement a Web Application Firewall (WAF) with rules to detect and block XSS attacks, specifically targeting the Logo Slider plugin's configuration pages.
Analyze the WordPress database for suspicious JavaScript code within the plugin's configuration tables.
Monitor user activity within the WordPress dashboard for unusual behavior, such as multiple attempts to modify plugin settings or the creation of new administrator accounts.
Use a Content Security Policy (CSP) to restrict the execution of JavaScript from untrusted sources.
Update the Logo Slider plugin to version 4.9.0 or later, which includes a fix for this vulnerability.
Implement input validation to sanitize all user-supplied data before storing it in the database.
Implement output encoding (e.g., HTML escaping) to properly sanitize data before displaying it in the dashboard.
Review and audit the plugin's code to identify and remediate any other potential XSS vulnerabilities.
Implement a Web Application Firewall (WAF) to filter malicious requests.
Enforce the principle of least privilege, limiting the permissions of users to only what is necessary for their roles.
Regularly back up the WordPress website and database to facilitate recovery in case of a successful attack.