CVE-2020-4875
📋 TL;DR
IBM Cognos Controller versions 10.4.0 through 10.4.2 contain an XML External Entity (XXE) vulnerability that allows remote attackers to read sensitive files from the server or cause denial of service through resource consumption. This affects organizations using these specific versions of IBM's financial consolidation software. The vulnerability is triggered when the application processes malicious XML data.
💻 Affected Systems
- IBM Cognos Controller
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise through file disclosure of sensitive data like passwords, configuration files, or database credentials, potentially leading to data exfiltration and further system compromise.
Likely Case
Unauthorized reading of server files containing sensitive information, potentially exposing credentials, configuration data, or business information stored on the affected system.
If Mitigated
Limited impact with proper network segmentation and XML parsing controls, potentially only causing minor service disruption if external entity resolution is blocked.
🎯 Exploit Status
XXE vulnerabilities typically have low exploitation complexity and can be exploited without authentication if vulnerable endpoints are exposed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply interim fix or upgrade to version 10.4.3 or later
Vendor Advisory: https://www.ibm.com/support/pages/node/6509856
Restart Required: Yes
Instructions:
1. Review IBM advisory at provided URL. 2. Apply the recommended interim fix or upgrade to version 10.4.3 or later. 3. Restart the Cognos Controller service. 4. Verify the fix by testing XML processing functionality.
🔧 Temporary Workarounds
Disable XML External Entity Processing
allConfigure XML parsers to disable external entity resolution
Configure XML parser settings to set features: XMLConstants.FEATURE_SECURE_PROCESSING = true, "http://xml.org/sax/features/external-general-entities" = false, "http://xml.org/sax/features/external-parameter-entities" = false
Input Validation and Filtering
allImplement strict input validation for XML data
Implement XML schema validation and filter/block XML containing DOCTYPE declarations or external entity references
🧯 If You Can't Patch
- Implement strict network segmentation to isolate Cognos Controller from untrusted networks
- Deploy a web application firewall (WAF) with XXE protection rules to block malicious XML payloads
🔍 How to Verify
Check if Vulnerable:
Check IBM Cognos Controller version via administrative console or configuration files. If version is 10.4.0, 10.4.1, or 10.4.2, the system is vulnerable.Check Version:
Check version in Cognos Controller administrative interface or configuration files (location varies by installation)Verify Fix Applied:
After applying patch, verify version is 10.4.3 or later. Test XML processing with safe payloads to ensure functionality remains while XXE vectors are blocked.📡 Detection & Monitoring
Log Indicators:
- Unusual XML parsing errors
- Multiple large XML file processing attempts
- Failed file access attempts from XML parser context
Network Indicators:
- HTTP requests containing XML with DOCTYPE declarations or external entity references
- Unusual outbound connections initiated by XML parser
SIEM Query:
source="cognos_controller" AND (message="*DOCTYPE*" OR message="*ENTITY*" OR message="*XXE*")