CVE-2025-14759
📋 TL;DR
This vulnerability in Amazon S3 Encryption Client for .NET allows users with write access to an S3 bucket to replace encrypted data keys with malicious ones that decrypt to different plaintext when using instruction files. This affects .NET applications using the vulnerable S3 encryption client with instruction file mode. Attackers could potentially manipulate encrypted data without detection.
💻 Affected Systems
- Amazon S3 Encryption Client for .NET
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Data integrity compromise where encrypted files are silently replaced with different content, potentially leading to data corruption, fraud, or malicious content distribution.
Likely Case
Privileged users with write access could manipulate encrypted data in shared buckets, affecting data integrity for applications relying on the encryption client.
If Mitigated
With proper access controls limiting bucket write permissions and monitoring for unusual S3 operations, impact is significantly reduced.
🎯 Exploit Status
Requires write access to S3 bucket and knowledge of instruction file usage. No public exploits known at advisory publication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.2.0
Vendor Advisory: https://aws.amazon.com/security/security-bulletins/AWS-2025-032/
Restart Required: Yes
Instructions:
1. Update NuGet package reference to Amazon.Extensions.S3.Encryption version 3.2.0 or later. 2. Rebuild and redeploy affected .NET applications. 3. Test encryption/decryption functionality.
🔧 Temporary Workarounds
Switch to metadata mode
allConfigure S3 encryption client to use metadata mode instead of instruction files for storing encrypted data keys.
// C# configuration: new AmazonS3EncryptionClientV2Config { StorageMode = CryptoStorageMode.ObjectMetadata }
🧯 If You Can't Patch
- Implement strict IAM policies to limit S3 bucket write access to essential users only.
- Enable S3 server access logging and monitor for unusual PutObject operations on instruction files.
🔍 How to Verify
Check if Vulnerable:
Check NuGet package version in .csproj or packages.config for Amazon.Extensions.S3.Encryption < 3.2.0.Check Version:
dotnet list package | findstr Amazon.Extensions.S3.EncryptionVerify Fix Applied:
Verify package version is 3.2.0+ and test encryption/decryption with instruction files to ensure key commitment validation.📡 Detection & Monitoring
Log Indicators:
- Unusual S3 PutObject operations on .instruction files
- Multiple encryption key modifications for same object
Network Indicators:
- Unexpected S3 API calls modifying instruction files from unauthorized sources
SIEM Query:
source="aws.cloudtrail" eventName="PutObject" requestParameters.key LIKE "%.instruction" | stats count by userIdentity.arn