Source: cve@mitre.org
The sanitize_string function in Zenphoto before 1.4.9 does not properly sanitize HTML tags, which allows remote attackers to perform a cross-site scripting (XSS) attack by wrapping a payload in "<<script></script>script>payload<script></script></script>", or in an image tag, with the payload as the onerror event.
Zenphoto versions prior to 1.4.9 are vulnerable to a cross-site scripting (XSS) attack due to improper HTML sanitization. This allows attackers to inject malicious scripts into web pages viewed by other users, potentially leading to account compromise, data theft, or website defacement.
Step 1: Payload Injection: The attacker crafts a malicious payload, such as <script>alert('XSS')</script> or <img src=x onerror=alert('XSS')>. This payload is designed to execute JavaScript code when rendered by the victim's browser.
Step 2: Input Submission: The attacker submits the malicious payload through a vulnerable input field within the Zenphoto application. This could be a comment field, a user profile field, or any other area where user-supplied content is displayed.
Step 3: Data Storage: The Zenphoto application stores the attacker's input, including the malicious payload, in its database or other storage mechanism.
Step 4: Data Retrieval and Rendering: When a victim views the page containing the attacker's input, the Zenphoto application retrieves the stored data and renders it in the victim's browser.
Step 5: Payload Execution: Due to the lack of proper sanitization, the malicious HTML tags and JavaScript code are executed by the victim's browser, leading to the execution of the attacker's payload. This could result in various malicious actions, such as stealing cookies, redirecting the user to a phishing site, or defacing the website.
The vulnerability stems from the sanitize_string function's failure to adequately filter HTML tags. Specifically, the function allows for the injection of malicious JavaScript code within HTML tags, such as <script> tags or image tags using the onerror event. The root cause is a flawed regular expression or logic within the sanitization function that fails to properly neutralize or remove malicious HTML constructs. This allows attackers to bypass the intended security measures and execute arbitrary code in the context of the victim's browser.
While no specific APT groups are directly linked to this vulnerability, it is a low-hanging fruit that could be exploited by various threat actors, including script kiddies and opportunistic attackers. Not listed on CISA KEV.
Network Intrusion Detection Systems (NIDS): Monitor for suspicious HTTP requests containing common XSS payloads in GET or POST parameters, such as <script>, onerror, and javascript:. Implement custom signatures based on known XSS attack patterns.
Web Application Firewalls (WAFs): Deploy a WAF to filter malicious input and block XSS attempts. Configure the WAF to detect and block XSS payloads based on signatures and heuristic analysis.
Server-Side Logging: Enable detailed logging of user input and output. Review logs for suspicious activity, such as unusual HTML tags or JavaScript code in user-generated content.
Client-Side Monitoring: Use browser extensions or security tools to detect and block XSS attacks on the client side. This can help identify and prevent attacks that bypass server-side defenses.
Forensic Analysis: Examine web server logs and database records for evidence of XSS attacks, such as unusual HTTP requests, malicious code injection attempts, and successful payload executions.
Upgrade Zenphoto: Update to Zenphoto version 1.4.9 or later. This version includes a fix for the XSS vulnerability.
Input Validation: Implement robust input validation to sanitize and filter user-supplied data. This should include blacklisting or whitelisting specific HTML tags and attributes.
Output Encoding: Properly encode output to prevent XSS attacks. Use appropriate encoding techniques, such as HTML entity encoding, to escape special characters in user-generated content.
Content Security Policy (CSP): Implement a Content Security Policy (CSP) to restrict the sources from which the browser can load resources, such as scripts, stylesheets, and images. This can help mitigate the impact of XSS attacks.
Regular Security Audits: Conduct regular security audits and penetration testing to identify and address vulnerabilities in the Zenphoto application.