CVE-2021-25962
📋 TL;DR
CVE-2021-25962 is a formula injection vulnerability in the Shuup e-commerce platform that allows customers to inject malicious payloads into billing address fields. When administrators export and open affected data in Excel, the payload executes, potentially compromising their system. This affects Shuup versions 0.4.2 through 2.10.8.
💻 Affected Systems
- Shuup
📦 What is this software?
Shuup by Shuup
⚠️ Risk & Real-World Impact
Worst Case
Complete compromise of administrator workstation through arbitrary code execution when opening malicious Excel files, potentially leading to lateral movement within the network.
Likely Case
Local code execution on administrator's machine when opening exported Excel reports, potentially stealing credentials or installing malware.
If Mitigated
No impact if proper input validation and sanitization are implemented, or if administrators use protected view in Excel.
🎯 Exploit Status
Exploitation requires customer account creation (typically public registration) and administrator interaction with Excel file.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.10.9 and later
Vendor Advisory: https://github.com/shuup/shuup/commit/0a2db392e8518410c282412561461cd8797eea51
Restart Required: No
Instructions:
1. Update Shuup to version 2.10.9 or later. 2. Apply the patch commit 0a2db392e8518410c282412561461cd8797eea51 if manual patching is needed. 3. Verify input sanitization for all user-controlled fields in reports.
🔧 Temporary Workarounds
Input Sanitization
allImplement server-side validation to strip or escape Excel formula characters (=, +, -, @) from user inputs before storage.
# Example Python sanitization:
import re
def sanitize_excel_input(value):
# Remove leading formula characters
return re.sub(r'^[=+\-@]', '', str(value))
Excel Protected View
windowsConfigure Excel to always open downloaded files in Protected View to prevent formula execution.
🧯 If You Can't Patch
- Disable Excel report exports or restrict to trusted administrators only
- Implement web application firewall (WAF) rules to block formula injection patterns in user inputs
🔍 How to Verify
Check if Vulnerable:
Check Shuup version; if between 0.4.2 and 2.10.8 inclusive, system is vulnerable. Test by entering formula payload (e.g., =cmd|' /C calc'!A0) in billing address field and exporting to Excel.Check Version:
python -c "import shuup; print(shuup.__version__)" or check package managerVerify Fix Applied:
After patching, attempt formula injection in billing address; exported Excel should display payload as plain text without execution.📡 Detection & Monitoring
Log Indicators:
- Unusual formula characters (=, +, -, @) in order/billing address fields
- Multiple failed Excel export attempts from same user
Network Indicators:
- Patterns of formula injection in HTTP POST data to order endpoints
SIEM Query:
source="web_logs" AND (uri="/api/order" OR uri="/checkout") AND (body="=cmd" OR body="@cmd" OR body="+cmd" OR body="-cmd")🔗 References
- https://github.com/shuup/shuup/commit/0a2db392e8518410c282412561461cd8797eea51
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25962
- https://github.com/shuup/shuup/commit/0a2db392e8518410c282412561461cd8797eea51
- https://www.whitesourcesoftware.com/vulnerability-database/CVE-2021-25962
