Understanding CS-Cart 1.3.3 'install.php' Cross-Site Scripting
Understanding CS-Cart 1.3.3 'install.php' Cross-Site Scripting
What this paper is
This paper describes a Cross-Site Scripting (XSS) vulnerability found in the install.php file of CS-Cart version 1.3.3. XSS vulnerabilities allow an attacker to inject malicious scripts into web pages viewed by other users. In this case, the vulnerability is present if the install.php file is not removed after the initial installation of CS-Cart.
Simple technical breakdown
The install.php script, when still present on the server, is vulnerable to XSS. This means an attacker can trick a user into visiting a specially crafted URL or submitting a form that contains malicious JavaScript. When the install.php script processes this input without proper sanitization, it can execute the injected script in the victim's browser. The exploit uses a simple HTML form to send a POST request to the vulnerable install.php script, specifically targeting the step parameter. By manipulating this parameter, an attacker can trigger the XSS.
Complete code and payload walkthrough
The provided exploit code is a simple HTML file designed to be hosted by the attacker or the victim.
<html>
<form name="installform" method="post" action="http://<Victim Ip>/install.php">
<input type="text" name="step">
<input type="submit" id="nextbut" value="xss">
</form>
</html>Let's break down this code:
<html>: Standard HTML document opening tag.<form name="installform" method="post" action="http://<Victim Ip>/install.php">: This defines an HTML form.name="installform": Assigns a name to the form, which is not critical for the exploit itself but good practice.method="post": Specifies that the form data will be sent using the HTTP POST method. This is important because the vulnerability is triggered by data sent in the request body.action="http://<Victim Ip>/install.php": This is the crucial part. It defines the URL where the form data will be submitted.<Victim Ip>: This is a placeholder that the attacker must replace with the actual IP address or hostname of the vulnerable CS-Cart installation./install.php: This is the target script on the victim's server. The exploit relies on this file being present and accessible.
<input type="text" name="step">: This creates a text input field within the form.name="step": This is the name of the form field. Theinstall.phpscript likely processes a parameter namedstep. The exploit aims to inject malicious content into thisstepparameter.
<input type="submit" id="nextbut" value="xss">: This creates a submit button for the form.value="xss": This sets the text displayed on the button.
Payload Explanation:
The "payload" in this context is not traditional shellcode. Instead, it's the data that the HTML form sends to the vulnerable install.php script. The exploit suggests that by submitting a crafted value for the step parameter, an attacker can trigger the XSS.
The paper states: "After that open the HTML file you have just created and enter which ever step of the installation you would like to access. Step "3" is where the juiciest information is."
This implies that the install.php script likely has different "steps" of installation or functionality, controlled by the step parameter. If the script directly outputs the value of the step parameter into the HTML response without proper escaping, and if a specific step (like "3") involves displaying this parameter's value, then injecting HTML/JavaScript into the step parameter would result in XSS.
Mapping:
<html>-> Standard HTML structure.<form ... action="http://<Victim Ip>/install.php">-> Target URL for the exploit.<input type="text" name="step">-> The vulnerable input field.<input type="submit" ...>-> The mechanism to trigger the form submission.- The value entered into the
stepinput field (e.g., "3" or a crafted XSS string) -> The actual "payload" data sent to the server.
Unknowns:
- The exact content of the
install.phpscript and how it handles thestepparameter is not provided. - The specific XSS payload that would work is not detailed, only that "Step '3' is where the juiciest information is." This suggests that step 3 might display user-supplied data directly.
Practical details for offensive operations teams
- Required Access Level: No elevated access is required on the victim's server. The exploit targets the web application itself.
- Lab Preconditions:
- A vulnerable CS-Cart 1.3.3 installation must be running and accessible via HTTP/HTTPS.
- The
install.phpfile must not have been removed after the initial installation. This is a critical prerequisite. - The attacker needs to know the IP address or hostname of the victim's CS-Cart installation.
- Tooling Assumptions:
- A web browser to load the attacker-controlled HTML file.
- A simple text editor to create the HTML exploit file.
- Knowledge of the victim's IP/hostname.
- Execution Pitfalls:
install.phpremoved: If theinstall.phpfile has been deleted by the administrator, this exploit will not work. This is the most common failure point.- Network accessibility: The victim's server must be accessible from where the attacker is hosting the HTML file. Firewalls or network segmentation could block access.
- Web Application Firewall (WAF): Modern WAFs might detect and block simple XSS payloads, even in older applications.
- Incorrect Victim IP/Hostname: Submitting the form to the wrong address will not trigger the exploit.
- Browser Security Settings: Some browser security settings or extensions might prevent XSS execution.
- Tradecraft Considerations:
- Hosting the exploit: The attacker can host the HTML file on a compromised web server, a public pastebin (if the victim is likely to visit it), or even craft a malicious link to be sent via email or social media.
- Social Engineering: To get the victim to click the link or open the HTML file, social engineering tactics would likely be employed. The exploit itself doesn't automatically execute; it requires user interaction.
- Payload Delivery: The XSS payload could be used to:
- Steal session cookies (if not HttpOnly).
- Redirect the user to a phishing page.
- Deface the website (from the victim's perspective).
- Perform actions on behalf of the user within the CS-Cart application.
- Telemetry:
- Attacker Side: Web server logs showing requests to the attacker-hosted HTML file.
- Victim Side:
- Browser console errors if the script fails to execute.
- Network traffic logs showing the POST request to the victim's
/install.php. - Application logs on the CS-Cart server might show unusual requests to
install.phpwith crafted parameters, though this is less likely to be logged by default for XSS exploitation. - If the XSS is used to steal cookies, logs on the attacker's server receiving these cookies.
Where this was used and when
- Approximate Year: 2010. The paper was published in September 2010.
- Context: This vulnerability would have been relevant for administrators of CS-Cart version 1.3.3 who neglected to remove the
install.phpfile after setting up their e-commerce store. Attackers would target such misconfigured installations.
Defensive lessons for modern teams
- Remove Installation Files: Always remove sensitive installation scripts (
install.php,setup.php, etc.) from the web server after the application is deployed. This is a fundamental security hygiene practice. - Input Validation and Output Encoding: Web applications must rigorously validate all user-supplied input and properly encode output before rendering it in HTML. This prevents XSS by ensuring that user data is treated as data, not executable code.
- Web Application Firewalls (WAFs): Deploy and configure WAFs to detect and block common web attacks, including XSS. Keep WAF rules updated.
- Regular Security Audits: Conduct regular security audits and penetration tests of web applications to identify vulnerabilities like XSS before they can be exploited.
- Keep Software Updated: While this exploit targets an old version, it highlights the importance of patching and updating all software components, including the web application framework and its plugins.
ASCII visual (if applicable)
This exploit relies on a direct interaction between a user's browser and the vulnerable web application. An ASCII diagram is not particularly helpful for illustrating the core mechanism, which is a simple form submission. The vulnerability lies within the server-side script's handling of input.
Source references
- Exploit-DB Paper: CS-Cart 1.3.3 - 'install.php' Cross-Site Scripting
- Author: crmpays (LogicGate)
- Published: 2010-09-09
- URL: https://www.exploit-db.com/papers/14962
Original Exploit-DB Content (Verbatim)
# Exploit Title: [CS CART 1.3.3 INSTALL.PHP XSS]
# Date: [2010-09-08]
# Author: [LogicGate]
# Software Link: [http://cs-cart.smartcode.com/]
# Version: [1.3.3]
# Tested on: [N/A]
# CVE : [N/A]
If "install.php" was not removed after installation simply make an html file with the following code and replace <Victim Server> by the PATH to "install.php" example:"http://www.nonexistant.com/install.php":
<html>
<form name="installform" method="post" action="http://<Victim Ip>/install.php">
<input type="text" name="step">
<input type="submit" id="nextbut" value="xss">
</form>
</html>
After that open the HTML file you have just created and enter which ever step of the installation you would like to access. Step "3" is where the juiciest information is.