CVE-2021-41569
📋 TL;DR
CVE-2021-41569 is a local file inclusion vulnerability in SAS/Intrnet 9.4 that allows authenticated users to escape macro variable constraints and execute functions to read arbitrary files from the host operating system. This affects organizations using SAS/Intrnet 9.4 build 1520 and earlier with the default samples library configuration.
💻 Affected Systems
- SAS/Intrnet
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Attackers could read sensitive system files, configuration files, or data files, potentially leading to data exfiltration, credential theft, or further system compromise.
Likely Case
Authenticated users could read files they shouldn't have access to, potentially exposing sensitive application data or configuration information.
If Mitigated
With proper access controls and file system permissions, impact is limited to files accessible by the SAS application service account.
🎯 Exploit Status
Exploitation requires authenticated access to SAS/Intrnet. The vulnerability is well-documented with technical details available in public advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: SAS/Intrnet 9.4 build 1521 and later
Vendor Advisory: https://support.sas.com/kb/68/641.html
Restart Required: Yes
Instructions:
1. Apply SAS/Intrnet 9.4 build 1521 or later. 2. Remove or restrict access to the samples library. 3. Restart SAS/Intrnet services.
🔧 Temporary Workarounds
Remove Samples Library
allDelete or move the samples library directory to prevent access to vulnerable sample.webcsf1.sas program
rm -rf /path/to/sas/samples/library
mv /path/to/sas/samples/library /secure/location/
Restrict File System Access
linuxApply strict file system permissions to limit what files the SAS service account can read
chmod 750 /sensitive/directories
chown root:sasgroup /sensitive/directories
🧯 If You Can't Patch
- Remove or disable the samples library completely from all SAS/Intrnet installations
- Implement network segmentation to isolate SAS/Intrnet servers and restrict access to sensitive file systems
🔍 How to Verify
Check if Vulnerable:
Check SAS/Intrnet version: if build number is 1520 or lower, check if samples library exists and contains sample.webcsf1.sasCheck Version:
Check SAS installation logs or configuration files for build number, or use SAS management consoleVerify Fix Applied:
Verify SAS/Intrnet build number is 1521 or higher, and confirm samples library is removed or inaccessible📡 Detection & Monitoring
Log Indicators:
- Unusual file access patterns from SAS/Intrnet processes
- Access to sample.webcsf1.sas program in web logs
- Errors related to macro variable escaping in SAS logs
Network Indicators:
- HTTP requests to SAS/Intrnet with unusual parameter values attempting file path traversal
SIEM Query:
source="sas_logs" AND ("sample.webcsf1" OR "DS2CSF macro" OR file_access_patterns)