CVE-2018-9126
📋 TL;DR
CVE-2018-9126 is a directory traversal vulnerability in the DNNArticle module for DNN (DotNetNuke) that allows remote attackers to read the web.config file via a specially crafted URI. This exposes sensitive configuration data including database credentials. Any DNN installation using the vulnerable DNNArticle module version is affected.
💻 Affected Systems
- DNN (DotNetNuke) with DNNArticle module
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers obtain database credentials, leading to full database compromise, data exfiltration, and potential lateral movement to other systems.
Likely Case
Attackers read web.config to obtain database credentials, then access/modify database content or escalate privileges within the application.
If Mitigated
Attackers can read configuration files but cannot access the database due to network segmentation or credential rotation.
🎯 Exploit Status
Exploit is trivial - simply accessing the crafted URL returns the web.config file. Multiple public exploit examples exist.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to DNNArticle module version 12 or later
Vendor Advisory: https://www.dnnsoftware.com/community/security/security-center
Restart Required: No
Instructions:
1. Log into DNN admin portal. 2. Navigate to Extensions > Available Extensions. 3. Search for DNNArticle module updates. 4. Install the latest version (12+). 5. Verify the module is updated in the Installed Extensions list.
🔧 Temporary Workarounds
Remove DNNArticle module
allUninstall the vulnerable DNNArticle module if not required
Log into DNN admin > Extensions > Installed Extensions > Find DNNArticle > Uninstall
URL filtering
windowsBlock requests to /GetCSS.ashx with traversal patterns
Add URL rewrite rule in web.config or IIS to block requests containing '/web.config' in parameters
🧯 If You Can't Patch
- Implement strict network segmentation to isolate the DNN server from database servers
- Rotate all database credentials stored in web.config immediately
🔍 How to Verify
Check if Vulnerable:
Access http://[target]/GetCSS.ashx/?CP=%2fweb.config - if web.config content is returned, system is vulnerable.Check Version:
Check DNN admin portal: Extensions > Installed Extensions > Look for DNNArticle module versionVerify Fix Applied:
Attempt the same URL after patching - should return error or empty response, not web.config content.📡 Detection & Monitoring
Log Indicators:
- HTTP 200 responses to /GetCSS.ashx with CP parameter containing '/web.config'
- Unusual database connection attempts from web server IP
Network Indicators:
- HTTP GET requests to /GetCSS.ashx with traversal patterns in parameters
- Outbound database connections from web server following config file access
SIEM Query:
source="web_logs" AND uri_path="/GetCSS.ashx" AND query_string="*CP=*web.config*" AND response_code=200