CVE-2025-58576

Executive Summary

CVE-2025-58576 is a Cross-Site Request Forgery (CSRF) vulnerability affecting GroupSession Free edition prior to ver5.3.0, GroupSession byCloud prior to ver5.3.3, and GroupSession ZION prior to ver5.3.2. The vulnerability allows an attacker to perform unintended operations on behalf of an authenticated user if that user visits a malicious page while logged into the application. The CVSS score is 4.3 (Medium), with a low EPSS probability of 0.0%, indicating limited active exploitation in the wild. No public proof-of-concept or exploit code is currently available. The vendor has not released a specific patch but recommends upgrading to the latest version.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a self-hosted Java-based web application (GroupSession). No supply chain implications are identified.

CVSS Breakdown & Threat Level

• CVSS Score: 4.3 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
• Attack Vector: Network
• Attack Complexity: Low
• Privileges Required: None
• User Interaction: Required
• Scope: Unchanged
• Confidentiality Impact: None
• Integrity Impact: Low
• Availability Impact: None

Threat Level: Medium. The vulnerability requires user interaction and does not lead to data disclosure or service disruption, but it can enable unauthorized actions within the application.

Deep Dive & Mechanics

The vulnerability is a classic CSRF flaw. GroupSession does not implement anti-CSRF tokens or same-site cookie attributes in its forms and state-changing requests. An attacker can craft a malicious HTML page or email that, when visited by an authenticated user, triggers a forged request to the GroupSession server. Because the user's session cookie is automatically sent with the request, the server processes the action as if initiated by the legitimate user.

Attack Scenario:

1. An attacker identifies a state-changing endpoint in GroupSession (e.g., changing user settings, creating a new user, or modifying group permissions).
2. The attacker crafts a malicious page containing an auto-submitting form or an image tag pointing to that endpoint.
3. The attacker lures an authenticated GroupSession user to visit the malicious page (e.g., via phishing email or social media).
4. The user's browser sends the forged request with the session cookie.
5. The server executes the unintended operation.

Root Cause: Lack of CSRF protection mechanisms such as:

• Anti-CSRF tokens in forms
• SameSite cookie attribute (None/Strict/Lax)
• Origin/Referer header validation

Vulnerable vs. Patched Code

Vulnerable Code (Example - Hypothetical):

// Vulnerable: No CSRF token validation
@RequestMapping(value = "/user/update", method = RequestMethod.POST)
public String updateUser(@RequestParam String email, HttpSession session) {
    User user = (User) session.getAttribute("user");
    user.setEmail(email);
    userDao.update(user);
    return "success";
}

Patched Code (Example - Hypothetical):

// Patched: CSRF token validation added
@RequestMapping(value = "/user/update", method = RequestMethod.POST)
public String updateUser(@RequestParam String email, 
                         @RequestParam String csrfToken, 
                         HttpSession session) {
    String expectedToken = (String) session.getAttribute("csrfToken");
    if (!expectedToken.equals(csrfToken)) {
        throw new SecurityException("Invalid CSRF token");
    }
    User user = (User) session.getAttribute("user");
    user.setEmail(email);
    userDao.update(user);
    return "success";
}

Note: Actual patched code is not publicly available. The vendor recommends upgrading to the latest version (5.3.0+ for Free, 5.3.3+ for byCloud, 5.3.2+ for ZION) which presumably includes CSRF protections.

Exploitation & Lab Setup

Red Team

Prerequisites:

• A running instance of GroupSession (vulnerable version)
• An authenticated user session
• A web server to host the malicious page

Step 1: Identify a state-changing endpoint.
Use browser developer tools or a proxy (e.g., Burp Suite) to capture a POST request that changes user data (e.g., email, password, or group membership).

Step 2: Craft the malicious HTML page.
Create an HTML file with an auto-submitting form:

<html>
<body>
<form id="csrf" action="http://target-group-session/user/update" method="POST">
  <input type="hidden" name="email" value="attacker@evil.com">
</form>
<script>document.getElementById('csrf').submit();</script>
</body>
</html>

Step 3: Host the page and lure the victim.
Host the HTML on an attacker-controlled server and send the link to the victim via email or social engineering.

Step 4: Execute.
When the victim visits the page while logged into GroupSession, the form auto-submits, changing their email to the attacker's address.

Blue Team

Detection:

• Monitor for unusual POST requests to sensitive endpoints (e.g., /user/update, /admin/*) without a valid Referer header.
• Look for multiple requests from the same IP to different user accounts within a short time window.
• Enable logging of all state-changing operations and correlate with session IDs.

Prevention:

• Implement anti-CSRF tokens in all forms.
• Set SameSite cookie attribute to Lax or Strict.
• Validate Origin/Referer headers for sensitive requests.
• Use CAPTCHA for critical operations (e.g., password changes).

Indicators of Compromise (IOCs)

• Network:
  • POST requests to /user/update, /group/create, /admin/user/delete without a Referer header or with an unexpected Referer.
  • Repeated requests from the same IP to multiple user accounts.
• Logs:
  • Application logs showing state changes (e.g., email updates) without corresponding user interaction.
  • Web server logs showing requests with missing or spoofed Referer headers.
• Host:
  • Unusual browser history or cache entries pointing to attacker-controlled domains.
  • Presence of malicious HTML files or scripts on the victim's machine (if downloaded).

Detection Engineering

YARA Rule

rule detect_csrf_attack_groupSession {
    meta:
        description = "Detects CSRF attack patterns targeting GroupSession"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-58576"
    strings:
        $csrf_form = /<form[^>]*action=["']http:\/\/[^"']*\/user\/update["']/
        $csrf_script = /document\.getElementById\(['"]csrf['"]\)\.submit\(\)/
        $csrf_img = /<img[^>]*src=["']http:\/\/[^"']*\/user\/update["']/
    condition:
        any of them
}

Sigma Rule

title: CSRF Attack Against GroupSession
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects potential CSRF attempts targeting GroupSession endpoints
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        c-uri|contains:
            - '/user/update'
            - '/group/create'
            - '/admin/user/delete'
        cs-referer|isnull: true
    condition: selection
falsepositives:
    - Legitimate requests from external tools
level: medium

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-58576 CSRF Attempt Against GroupSession"; flow:to_server,established; http.method; content:"POST"; http.uri; content:"/user/update"; http.referer; content:!"Referer"; classtype:attempted-recon; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Upgrade GroupSession to the latest version:
   • Free edition: ver5.3.0 or later
   • byCloud: ver5.3.3 or later
   • ZION: ver5.3.2 or later
2. If upgrade is not possible, implement a Web Application Firewall (WAF) rule to block requests without a valid Referer header.
3. Enable SameSite cookie attribute (set to Lax or Strict) in the application server configuration.

Long-term Measures:

• Conduct a security audit of all state-changing endpoints to ensure CSRF protection is in place.
• Implement anti-CSRF tokens using a framework like OWASP CSRFGuard.
• Educate users about phishing attacks and the importance of logging out after sessions.
• Monitor application logs for suspicious activity.

Workaround:

• Disable automatic form submission by adding a CAPTCHA to sensitive operations.
• Use custom HTTP headers (e.g., X-Requested-With: XMLHttpRequest) and validate them server-side.

Valters IT
DevSecOps & Cyber Threat Intelligence Expert