CVE-2021-47763

Executive Summary

CVE-2021-47763 is a critical SQL injection vulnerability discovered in the Aimeos 2021.10 LTS e-commerce framework. The flaw resides in the JSON API sort parameter, specifically within the /jsonapi/review endpoint. An unauthenticated attacker can inject arbitrary SQL commands by sending crafted GET requests, leading to unauthorized disclosure of database schema information, including table and column names. The vulnerability has a CVSS score of 0.0 in the NVD due to incomplete scoring, but based on the technical details, it represents a high-severity information disclosure risk. No official patch has been confirmed, and no public exploit code or Nuclei template is available at this time.

Supply Chain & Package Security

Aimeos is a PHP-based e-commerce framework distributed via Composer (Packagist). This vulnerability affects the core JSON API component, which is a standard part of the Aimeos package. Organizations using Aimeos 2021.10 LTS should treat this as a supply chain risk, as the vulnerable component is integral to the framework's API functionality. No known malicious packages have been identified, but the lack of a patch increases the risk of supply chain compromise through unpatched installations.

CVSS Breakdown & Threat Level

The NVD has assigned a CVSS score of 0.0, which is likely an error or placeholder. Based on the vulnerability details, a more accurate assessment is:

• Attack Vector (AV): Network (N) – The vulnerability is exploitable remotely.
• Attack Complexity (AC): Low (L) – No special conditions are required.
• Privileges Required (PR): None (N) – No authentication is needed.
• User Interaction (UI): None (N) – No user action is required.
• Scope (S): Unchanged (U) – The impact is confined to the database.
• Confidentiality (C): High (H) – Database schema information is exposed.
• Integrity (I): None (N) – No data modification is possible.
• Availability (A): None (N) – No denial of service.

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

Threat Level: High. The vulnerability allows unauthenticated attackers to extract sensitive database schema information, which can be used to craft more targeted attacks.

Deep Dive & Mechanics

The vulnerability exists in the JSON API endpoint /jsonapi/review. The sort parameter is used to specify the order of results (e.g., sort=rating). The application fails to properly sanitize or parameterize the input before incorporating it into SQL queries.

Root Cause: The sort parameter is directly concatenated into an SQL ORDER BY clause without proper escaping or validation. This allows an attacker to inject arbitrary SQL after the ORDER BY keyword.

Attack Vector: An attacker sends a GET request to the vulnerable endpoint with a malicious sort parameter. For example:

GET /jsonapi/review?sort=rating ASC, (SELECT 1 FROM information_schema.tables WHERE table_schema=database() LIMIT 1)--

This injection can be used to extract database metadata by using subqueries that return information about table and column names.

Impact: The primary impact is information disclosure. An attacker can enumerate the database schema, including table names, column names, and data types. This information can be used to plan further attacks, such as data exfiltration or privilege escalation.

Vulnerable vs. Patched Code

Vulnerable Code (Conceptual):

// Vulnerable: Direct concatenation of user input
$sort = $_GET['sort'];
$query = "SELECT * FROM reviews ORDER BY " . $sort;

Patched Code (Conceptual):

// Patched: Whitelist allowed sort columns
$allowedSorts = ['rating', 'created_at', 'updated_at'];
$sort = $_GET['sort'];
if (in_array($sort, $allowedSorts)) {
    $query = "SELECT * FROM reviews ORDER BY " . $sort;
} else {
    // Handle invalid sort parameter
}

Explanation: The vulnerable code directly concatenates user input into the SQL query. The patched code uses a whitelist approach, only allowing predefined column names. Alternatively, parameterized queries with prepared statements could be used, but ORDER BY clauses cannot be parameterized in standard SQL, making whitelisting the most secure approach.

Exploitation & Lab Setup

Red Team (Offensive)

Lab Setup:

1. Install Aimeos 2021.10 LTS on a local server (e.g., using Docker or a LAMP stack).
2. Ensure the /jsonapi/review endpoint is accessible.

Exploitation Steps:

1. Identify the vulnerability: Send a request with a simple injection to test:

   GET /jsonapi/review?sort=rating ASC, (SELECT 1)--
   

   If the response is normal, the injection is likely working.

2. Extract table names:

   GET /jsonapi/review?sort=rating ASC, (SELECT table_name FROM information_schema.tables WHERE table_schema=database() LIMIT 1)--
   

   The response may include the table name in the error message or in the sorted data.

3. Extract column names:

   GET /jsonapi/review?sort=rating ASC, (SELECT column_name FROM information_schema.columns WHERE table_name='reviews' LIMIT 1)--
   

Note: Since no public exploit code is available, these manual injection techniques are the primary method of exploitation.

Blue Team (Defensive)

Detection:

1. Monitor web server logs for unusual sort parameter values containing SQL keywords (e.g., SELECT, UNION, FROM, WHERE).
2. Deploy a Web Application Firewall (WAF) with rules to block SQL injection patterns in query parameters.
3. Use database activity monitoring to detect anomalous queries.

Mitigation:

1. Apply input validation and whitelisting for the sort parameter.
2. Upgrade to a patched version of Aimeos if available.
3. Implement least privilege for database users to limit the impact of information disclosure.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP GET requests to /jsonapi/review with sort parameter containing SQL keywords (e.g., SELECT, UNION, FROM, information_schema).
  • Unusual response sizes or error messages containing database table/column names.

• Log IOCs:

  • Web server logs showing requests with sort parameter values like rating ASC, (SELECT ...).
  • Database logs showing ORDER BY clauses with subqueries.

• File IOCs:

  • No specific file IOCs, as this is a server-side vulnerability.

Detection Engineering

YARA Rule

rule CVE_2021_47763_SQLi_Sort_Parameter {
    meta:
        description = "Detects SQL injection attempts targeting the sort parameter in Aimeos JSON API"
        author = "Valters IT"
        date = "2025-04-10"
        cve = "CVE-2021-47763"
    strings:
        $sqli1 = /sort=[^&]*\b(SELECT|UNION|FROM|WHERE|ORDER|BY|INTO|LOAD_FILE|INFORMATION_SCHEMA)\b/i
        $sqli2 = /sort=[^&]*\b(0x[0-9a-fA-F]+|CHAR\(|CONCAT\(|BENCHMARK\(|SLEEP\()/i
        $sqli3 = /sort=[^&]*\b(OR|AND)\s+\d+=\d+/i
    condition:
        any of them
}

Sigma Rule

title: Aimeos JSON API SQL Injection via sort Parameter
id: 8f4a3b2c-1d5e-4f6a-8b7c-9d0e1f2a3b4c
status: experimental
description: Detects SQL injection attempts against the Aimeos JSON API sort parameter
author: Valters IT
date: 2025-04-10
logsource:
    category: webserver
    product: apache
    service: access_combined
detection:
    selection:
        cs-uri-query|contains: 
            - '/jsonapi/review'
        cs-uri-query|re: 
            - 'sort=.*\b(SELECT|UNION|FROM|WHERE|ORDER|BY|INTO|LOAD_FILE|INFORMATION_SCHEMA)\b'
            - 'sort=.*\b(0x[0-9a-fA-F]+|CHAR\(|CONCAT\(|BENCHMARK\(|SLEEP\()'
            - 'sort=.*\b(OR|AND)\s+\d+=\d+'
    condition: selection
falsepositives:
    - Legitimate use of SQL keywords in sort parameter (unlikely)
level: high

Suricata Rule

alert http any any -> any any (msg:"CVE-2021-47763 Aimeos JSON API SQL Injection via sort Parameter"; flow:to_server,established; content:"/jsonapi/review"; http_uri; pcre:"/sort=[^&]*\b(SELECT|UNION|FROM|WHERE|ORDER|BY|INTO|LOAD_FILE|INFORMATION_SCHEMA)\b/i"; pcre:"/sort=[^&]*\b(0x[0-9a-fA-F]+|CHAR\(|CONCAT\(|BENCHMARK\(|SLEEP\()/i"; pcre:"/sort=[^&]*\b(OR|AND)\s+\d+=\d+/i"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the JSON API endpoint if not required, or restrict access to trusted IPs only.
2. Implement input validation for the sort parameter using a whitelist of allowed values.
3. Deploy a WAF with rules to block SQL injection patterns.

Long-term Fix:

1. Upgrade Aimeos to a version where this vulnerability is patched (if available).
2. Conduct a code review of all JSON API endpoints to ensure proper input sanitization.
3. Implement parameterized queries for all database interactions, especially for ORDER BY clauses (using whitelisting).

Workaround:

• Modify the application code to validate the sort parameter against a list of allowed column names before using it in SQL queries.

Valters IT
Senior DevSecOps & Cyber Threat Intelligence Expert