CVE-2021-42258
📋 TL;DR
CVE-2021-42258 is a critical SQL injection vulnerability in BQE BillQuick Web Suite that allows unauthenticated attackers to execute arbitrary SQL commands. This can lead to remote code execution via xp_cmdshell, enabling ransomware deployment. Organizations using affected versions of BillQuick Web Suite are at risk.
💻 Affected Systems
- BQE BillQuick Web Suite
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with ransomware deployment, data exfiltration, and persistent backdoor installation via MSSQLSERVER$ account privileges.
Likely Case
Ransomware deployment leading to data encryption, business disruption, and potential data theft as observed in real-world attacks.
If Mitigated
Limited impact with proper network segmentation, SQL injection prevention controls, and restricted database permissions.
🎯 Exploit Status
Actively exploited in the wild since October 2021 for ransomware deployment. Exploitation requires minimal technical skill.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 22.0.9.1 and later
Vendor Advisory: https://www.bqe.com/support/security-advisory/
Restart Required: Yes
Instructions:
1. Backup all data and configurations. 2. Download and install BillQuick Web Suite version 22.0.9.1 or later from BQE support portal. 3. Restart the application and verify functionality.
🔧 Temporary Workarounds
Disable xp_cmdshell
windowsPrevents command execution via SQL injection by disabling the xp_cmdshell stored procedure in MSSQL.
EXEC sp_configure 'show advanced options', 1;
RECONFIGURE;
EXEC sp_configure 'xp_cmdshell', 0;
RECONFIGURE;
Network Segmentation
allIsolate BillQuick servers from internet and restrict access to necessary internal networks only.
🧯 If You Can't Patch
- Implement a web application firewall (WAF) with SQL injection rules to block exploitation attempts.
- Restrict database user permissions to prevent xp_cmdshell execution and implement input validation at application layer.
🔍 How to Verify
Check if Vulnerable:
Check BillQuick version in application interface or installation directory. Versions 2018-2021 before 22.0.9.1 are vulnerable.Check Version:
Check Help > About in BillQuick interface or examine installed program version in Windows Programs and Features.Verify Fix Applied:
Verify version is 22.0.9.1 or later and test SQL injection attempts are blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual SQL queries containing xp_cmdshell or command execution patterns in database logs
- Multiple failed login attempts or SQL errors in application logs
Network Indicators:
- SQL injection patterns in HTTP requests to BillQuick endpoints
- Outbound connections from database server to unknown IPs
SIEM Query:
source="web_logs" AND (uri="*txtID=*" AND (content="xp_cmdshell" OR content="EXEC" OR content="UNION"))🔗 References
- https://www.huntress.com/blog/threat-advisory-hackers-are-exploiting-a-vulnerability-in-popular-billing-software-to-deploy-ransomware
- https://www.huntress.com/blog/threat-advisory-hackers-are-exploiting-a-vulnerability-in-popular-billing-software-to-deploy-ransomware
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42258
