CVE-2021-38948
📋 TL;DR
IBM InfoSphere Information Server 11.7 has an XML External Entity Injection (XXE) vulnerability that allows attackers to read sensitive files from the server or cause denial of service through resource exhaustion. This affects organizations using IBM InfoSphere Information Server 11.7 for data integration and governance. Remote attackers can exploit this without authentication.
💻 Affected Systems
- IBM InfoSphere Information Server
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete server compromise including reading sensitive configuration files, database credentials, and system files, potentially leading to data exfiltration and further lateral movement.
Likely Case
Information disclosure of sensitive server files and potential denial of service through memory exhaustion attacks.
If Mitigated
Limited impact with proper network segmentation and XML parsing restrictions, though some information disclosure may still occur.
🎯 Exploit Status
XXE vulnerabilities are well-understood attack vectors with many public exploitation techniques available. While no specific public PoC exists for this CVE, the attack methodology is standardized.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Apply InfoSphere Information Server 11.7 Fix Pack 4 (11.7.1.4) or later
Vendor Advisory: https://www.ibm.com/support/pages/node/6509632
Restart Required: Yes
Instructions:
1. Download InfoSphere Information Server 11.7 Fix Pack 4 from IBM Fix Central. 2. Apply the fix pack following IBM's installation instructions. 3. Restart all InfoSphere Information Server services. 4. Verify the patch is applied correctly.
🔧 Temporary Workarounds
Disable XML External Entity Processing
allConfigure XML parsers to disable external entity resolution
Configure XML parser settings to set features: FEATURE_SECURE_PROCESSING=true, http://apache.org/xml/features/disallow-doctype-decl=true
Input Validation and Filtering
allImplement strict input validation for XML data
Implement XML schema validation and filter/block DOCTYPE declarations in user-supplied XML
🧯 If You Can't Patch
- Implement network segmentation to restrict access to InfoSphere servers
- Deploy web application firewall (WAF) with XXE protection rules
🔍 How to Verify
Check if Vulnerable:
Check if running InfoSphere Information Server version 11.7 without Fix Pack 4 appliedCheck Version:
Check the version in InfoSphere Information Server administration console or review installation logsVerify Fix Applied:
Verify that InfoSphere Information Server version shows 11.7.1.4 or later📡 Detection & Monitoring
Log Indicators:
- Unusual XML parsing errors
- Large XML file processing
- External entity resolution attempts in logs
Network Indicators:
- HTTP requests with XML payloads containing DOCTYPE declarations
- Outbound connections to external URLs from XML parsing
SIEM Query:
source="infosphere" AND (xml OR xxe OR doctype) AND (error OR exception)