CVE-2021-43155
📋 TL;DR
CVE-2021-43155 is a critical SQL injection vulnerability in Projectsworlds Online Book Store PHP v1.0 that allows attackers to execute arbitrary SQL commands via the 'bookisbn' parameter in cart.php. This affects all users running the vulnerable version of this PHP-based online bookstore software, potentially exposing database contents including user credentials and sensitive information.
💻 Affected Systems
- Projectsworlds Online Book Store PHP
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete database compromise allowing data theft, modification, or deletion; potential authentication bypass; possible remote code execution if database permissions allow.
Likely Case
Unauthorized access to sensitive data including user information, order details, and potentially administrative credentials stored in the database.
If Mitigated
Limited impact with proper input validation and parameterized queries preventing SQL injection.
🎯 Exploit Status
SQL injection via GET/POST parameter requires minimal technical skill; exploit details are publicly available in GitHub issues.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specified
Vendor Advisory: No official vendor advisory found
Restart Required: No
Instructions:
1. Review the GitHub issue for community fixes. 2. Implement parameterized queries in cart.php. 3. Add input validation for the bookisbn parameter. 4. Test thoroughly before deployment.
🔧 Temporary Workarounds
Input Validation Filter
allAdd server-side validation to only accept numeric ISBN values
In cart.php, add: if(!is_numeric($_GET['bookisbn'])) { die('Invalid ISBN'); }
WAF Rule Implementation
linuxDeploy web application firewall rules to block SQL injection patterns
ModSecurity rule: SecRule ARGS:bookisbn "@detectSQLi" "id:1001,phase:2,deny,status:403"
🧯 If You Can't Patch
- Isolate the application behind a reverse proxy with strict input filtering
- Implement network segmentation to limit database access from the application server
🔍 How to Verify
Check if Vulnerable:
Test by accessing cart.php?bookisbn=1' OR '1'='1 and observing if SQL errors appear or unexpected behavior occurs.Check Version:
Check PHP files for version comments or review project documentation; typically no built-in version command.Verify Fix Applied:
Attempt the same SQL injection test after fixes; should receive proper error handling or validation messages instead of SQL errors.📡 Detection & Monitoring
Log Indicators:
- Unusual SQL error messages in web server logs
- Multiple requests with SQL-like patterns in bookisbn parameter
- Unexpected database query patterns
Network Indicators:
- HTTP requests containing SQL keywords in bookisbn parameter
- Abnormal traffic patterns to cart.php
SIEM Query:
source="web_logs" AND uri="*cart.php*" AND (param="*bookisbn=*'*" OR param="*bookisbn=*%27*")