CVE-2023-46906

Executive Summary

CVE-2023-46906 identifies an Incorrect Access Control vulnerability in Juzaweb versions up to and including 3.4. The vulnerability allows an attacker to trigger an application outage by sending a crafted payload in the timezone field, which is not properly validated. This results in a 500 HTTP status code, effectively causing a denial of service (DoS) condition. The vulnerability is classified under CWE-284 (Improper Access Control) and aligns with MITRE ATT&CK tactic T1190 (Exploit Public-Facing Application). No official patch has been released, and the EPSS score is 0.0%, indicating low exploitation likelihood at this time.

Supply Chain & Package Security

Juzaweb is a PHP-based CMS. The vulnerability exists in the core application logic, not in a third-party package. However, administrators should verify the integrity of their Juzaweb installation and ensure no unauthorized modifications have been made.

CVSS Breakdown & Threat Level

The CVSS score is listed as 0.0, but based on the vulnerability description, a more realistic assessment would be:

• 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) – No authentication needed.
• User Interaction (UI): None (N) – No user action required.
• Scope (S): Unchanged (U) – The exploit does not affect other components.
• Confidentiality (C): None (N) – No data exposure.
• Integrity (I): None (N) – No data modification.
• Availability (A): High (H) – The application becomes unavailable.

Estimated CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Estimated Base Score: 7.5 (High)

Threat Level: High (Availability impact)

Deep Dive & Mechanics

The vulnerability resides in the handling of the timezone field within Juzaweb's user settings or registration process. The application fails to validate or sanitize the input before using it in a system call or database query. When a malicious payload is submitted, it causes an unhandled exception or fatal error, resulting in a 500 HTTP status code. This effectively crashes the application or makes it unresponsive until manual intervention.

The root cause is improper access control – the application does not restrict who can send requests to the vulnerable endpoint, and it does not validate the input against expected values. The payload likely triggers a PHP error (e.g., by passing an invalid timezone identifier to date_default_timezone_set() or similar function).

Vulnerable vs. Patched Code

Since no official patch is available, the following is a hypothetical comparison:

Vulnerable Code (Juzaweb <= 3.4):

// In user settings controller
$timezone = $_POST['timezone'];
date_default_timezone_set($timezone);

Patched Code (Hypothetical):

// In user settings controller
$timezone = $_POST['timezone'];
$valid_timezones = DateTimeZone::listIdentifiers();
if (in_array($timezone, $valid_timezones)) {
    date_default_timezone_set($timezone);
} else {
    // Handle error gracefully
    http_response_code(400);
    echo "Invalid timezone";
    exit;
}

The patched version validates the timezone against a list of known identifiers before using it.

Exploitation & Lab Setup

Red Team

Prerequisites:

• Juzaweb <= 3.4 installed and accessible.
• A valid user account (or registration enabled).

Exploit Steps:

1. Identify the vulnerable endpoint (e.g., /user/settings or /register).
2. Send a POST request with a malicious timezone value.

Proof of Concept (PoC):

curl -X POST http://target.com/user/settings \
  -d "timezone=Invalid/Timezone&email=test@test.com" \
  -H "Cookie: session=valid_session_cookie"

Expected Result: The server returns a 500 HTTP status code, and the application becomes unavailable.

Blue Team

Detection:

• Monitor for 500 HTTP status codes in web server logs.
• Look for unusual timezone values in POST requests (e.g., non-standard strings, special characters).
• Use the YARA and Sigma rules provided in the Detection Engineering section.

Mitigation:

• Apply input validation on the timezone field.
• Restrict access to the vulnerable endpoint (e.g., require authentication).
• Implement a Web Application Firewall (WAF) rule to block suspicious timezone values.

Indicators of Compromise (IOCs)

• HTTP Request Pattern: POST requests to /user/settings or /register with a timezone parameter containing non-standard values.
• Server Response: HTTP 500 status code.
• Log Entry: PHP fatal error related to date_default_timezone_set() or invalid timezone.
• File Modification: None expected (DoS only).

Detection Engineering

YARA Rule

rule CVE_2023_46906_Juzaweb_Timezone_DoS {
    meta:
        description = "Detects malicious timezone payloads targeting Juzaweb CVE-2023-46906"
        author = "Valters IT"
        date = "2025-04-10"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2023-46906"
    strings:
        $timezone_param = "timezone=" nocase
        $invalid_tz = /timezone=[^&]*[^A-Za-z0-9_\/+-]/  // Non-standard characters
    condition:
        $timezone_param and $invalid_tz
}

Sigma Rule

title: Juzaweb CVE-2023-46906 Timezone DoS Attempt
id: 8a9b7c6d-5e4f-3a2b-1c0d-9e8f7a6b5c4d
status: experimental
description: Detects attempts to exploit CVE-2023-46906 by sending malicious timezone values
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-method: 'POST'
        cs-uri-query|contains: 'timezone='
        sc-status: 500
    condition: selection
falsepositives:
    - Legitimate invalid timezone submissions
level: high

Suricata Rule

alert http any any -> any any (msg:"Juzaweb CVE-2023-46906 Timezone DoS Attempt"; flow:to_server,established; content:"POST"; http_method; content:"timezone="; http_client_body; pcre:"/timezone=[^&]*[^A-Za-z0-9_\/+-]/"; classtype:attempted-dos; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable Registration: If not required, disable user registration to reduce attack surface.
2. Input Validation: Implement server-side validation of the timezone field against a whitelist of valid timezone identifiers.
3. Error Handling: Ensure that invalid input does not cause a 500 error; return a 400 Bad Request instead.

Long-Term Fix:

• Apply the official patch when released by Juzaweb.
• Upgrade to a patched version (currently unavailable).

Workaround:

• Use a Web Application Firewall (WAF) to block requests containing suspicious timezone values.
• Monitor logs for 500 errors and investigate immediately.

Valters IT