CVE-2021-35963
📋 TL;DR
CVE-2021-35963 is an unauthenticated remote code execution vulnerability in the Orca HCM digital learning platform's file upload function. Attackers can upload malicious files containing scripts to execute arbitrary code on affected systems. This affects all organizations using vulnerable versions of Orca HCM.
💻 Affected Systems
- Orca HCM digital learning platform
📦 What is this software?
Orca Hcm by Learningdigital
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise allowing attackers to execute arbitrary commands, steal sensitive data, deploy ransomware, or pivot to other systems in the network.
Likely Case
Attackers upload web shells or malware to gain persistent access, exfiltrate sensitive HR and learning data, and potentially compromise user accounts.
If Mitigated
With proper file upload validation and web application firewalls, exploitation attempts would be blocked, limiting impact to failed attack attempts.
🎯 Exploit Status
The vulnerability is straightforward to exploit - attackers simply need to craft malicious file uploads. Public proof-of-concept details exist in security advisories.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not specifically documented in public advisories, but patches were released by the vendor
Vendor Advisory: https://www.chtsecurity.com/news/ba7b3ae7-14f3-4970-b3f6-4d97d8c7ea25
Restart Required: Yes
Instructions:
1. Contact Orca HCM vendor for the latest patched version. 2. Apply the security patch provided by the vendor. 3. Restart the application services. 4. Verify the fix is working by testing file upload functionality.
🔧 Temporary Workarounds
Implement strict file upload validation
allAdd server-side validation to restrict allowed file types and extensions
Deploy web application firewall rules
allConfigure WAF to block malicious file upload attempts and suspicious HTTP requests
🧯 If You Can't Patch
- Disable file upload functionality entirely if not required
- Implement network segmentation to isolate Orca HCM from critical systems
🔍 How to Verify
Check if Vulnerable:
Test file upload functionality by attempting to upload files with various extensions and checking if server-side validation is insufficientCheck Version:
Check Orca HCM version through admin interface or contact vendor supportVerify Fix Applied:
Attempt to upload malicious file types and verify they are rejected with proper error messages📡 Detection & Monitoring
Log Indicators:
- Unusual file upload attempts, especially with executable extensions
- Multiple failed upload attempts from single IP
- Uploads of files with double extensions
Network Indicators:
- HTTP POST requests to upload endpoints with suspicious file content
- Traffic patterns indicating file upload exploitation
SIEM Query:
source="orca_hcm_logs" AND (event="file_upload" AND (file_extension="php" OR file_extension="jsp" OR file_extension="asp" OR file_extension="exe"))