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How the CVE Works
The vulnerability in Amazon.IonDotnet (ion-dotnet) stems from improper stream handling in the `RawBinaryReader` class. When parsing binary Ion data, the library fails to validate the number of bytes read from the input stream. If an attacker supplies malformed or truncated binary Ion data, the deserialization process enters an infinite loop, consuming excessive CPU resources and leading to a denial-of-service (DoS) condition. This occurs because the parser continuously attempts to read additional bytes without proper termination checks, causing indefinite execution.
DailyCVE Form
Platform: Amazon.IonDotnet
Version: <=1.3.0
Vulnerability: Infinite Loop DoS
Severity: Medium
Date: 2023-XX-XX
What Undercode Say:
Exploitation:
1. Craft malformed binary Ion data.
2. Feed it to `RawBinaryReader` via `IonLoader`.
3. Trigger infinite parsing loop.
PoC Code:
using Amazon.IonDotnet;
using System.IO;
var malformedData = new byte[] { 0xE0, 0x01, 0x00, 0xEA }; // Truncated Ion binary
using var stream = new MemoryStream(malformedData);
var reader = IonReaderBuilder.Build(stream); // Infinite loop
Mitigation:
1. Upgrade to `ion-dotnet>=1.3.1`.
2. Validate input streams before parsing.
Detection:
Check installed version (NuGet): dotnet list package | grep Amazon.IonDotnet
Patch Analysis:
The fix introduces bounds checking in RawBinaryReader.ReadBytes(), ensuring loop termination.
References:
Affected Configurations:
- .NET apps using `ion-dotnet<=1.3.0` for binary Ion parsing.
Workaround:
None. Must upgrade.
Monitoring:
Log CPU spikes in .NET processes: perfmon /res
Additional Checks:
// Validate Ion data before processing:
try { IonLoader.Load(inputStream); }
catch (IonException e) { / Handle malformed data / }
Impacted Use Cases:
- AWS Lambda with Ion parsing.
- Serverless apps using Ion serialization.
Vendor Response:
AWS patched in v1.3.1 via commit `[bash]`.
Credits:
Josh Coleman (Symbotic).
Legal Notice:
Unauthorized exploitation prohibited.
End of Report.
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
