CVE-2021-44150
📋 TL;DR
CVE-2021-44150 is a cryptographic weakness vulnerability in tusdotnet client versions through 2.5.0 that uses SHA-1 for file content verification. This allows attackers to spoof file content by generating SHA-1 collisions, potentially leading to malicious file uploads being accepted as legitimate. Any application using the vulnerable tusdotnet client for file uploads is affected.
💻 Affected Systems
- tusdotnet
📦 What is this software?
Tusdotnet by Transloadit
⚠️ Risk & Real-World Impact
Worst Case
Attackers could upload malicious files that appear legitimate, potentially leading to malware distribution, data corruption, or supply chain attacks if the files are processed by downstream systems.
Likely Case
File integrity verification failures allowing unauthorized or malicious content to bypass checks, potentially compromising application security or data integrity.
If Mitigated
With proper network segmentation and additional file validation layers, impact is limited to potential file verification failures without broader system compromise.
🎯 Exploit Status
SHA-1 collision attacks are well-documented and tools exist to generate collisions, making exploitation straightforward for attackers with basic cryptographic knowledge.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 2.6.0 and later
Vendor Advisory: https://github.com/tusdotnet/tusdotnet/issues/157
Restart Required: Yes
Instructions:
1. Update tusdotnet package to version 2.6.0 or later. 2. Rebuild and redeploy your application. 3. Verify the update by checking the package version in your project.
🔧 Temporary Workarounds
Implement additional file validation
allAdd secondary file validation using stronger hash algorithms (SHA-256 or SHA-3) or file signature checking
Disable SHA-1 verification
allConfigure tusdotnet client to use stronger hash algorithms if supported by your version
🧯 If You Can't Patch
- Implement network-level controls to restrict file uploads to trusted sources only
- Add application-level file validation using modern cryptographic hash functions before processing uploaded files
🔍 How to Verify
Check if Vulnerable:
Check your project's package references for tusdotnet version 2.5.0 or earlierCheck Version:
dotnet list package | findstr tusdotnet (Windows) or dotnet list package | grep tusdotnet (Linux)Verify Fix Applied:
Verify tusdotnet package version is 2.6.0 or later in your project dependencies📡 Detection & Monitoring
Log Indicators:
- Failed file integrity checks
- Unexpected file upload patterns
- SHA-1 hash verification warnings
Network Indicators:
- Unusual file upload traffic patterns
- Multiple failed upload attempts followed by successful upload
SIEM Query:
source="application_logs" AND ("SHA-1" OR "file verification failed" OR "integrity check")