Fileupload Gunner - Project Hot

Two recent vulnerability classes illustrate the persistent heat:

In each case, the root cause was trusting client-supplied file metadata.

The most popular “hot” implementation right now is GunnerPro, a CLI tool that:

Sample run:

gunnerpro -u https://target.com/upload -p "file" -t 50

Result:

[CRITICAL] Uploaded shell.php.phtml - accessible at /uploads/shell.php.phtml
[!] Bypass used: Invalid extension .phtml accepted due to missing .php blacklist.

New “hot” scripts integrate LLMs to mutate payloads in real-time. For example:

// routes/upload.js - The "Gunner" endpoint
const AWS = require('aws-sdk');
const  v4: uuidv4  = require('uuid');
const s3 = new AWS.S3( region: 'us-east-1', signatureVersion: 'v4' );
app.post('/api/gunner/request-upload', async (req, res) => 
const  filename, filetype, projectId  = req.body;
// Authentication & Authorization for Gunner project
if (!req.user.hasAccessTo(projectId)) 
return res.status(403).json( error: "Not authorized for this hot zone" );
 fileupload gunner project hot
const key = gunner-hot-uploads/$projectId/$uuidv4()-$filename;
const params = 
Bucket: process.env.HOT_BUCKET,
Key: key,
Expires: 3600, // URL valid for 1 hour
ContentType: filetype,
// Optional: Server-side encryption for "hot" sensitive data
ServerSideEncryption: 'AES256'
;
const uploadUrl = await s3.getSignedUrlPromise('putObject', params);
res.json( uploadUrl, key, fileId: uuidv4() );
);
 In each case, the root cause was trusting

Do not route the file through your application server (EC2, Kubernetes pod, etc.). That server is a bottleneck.

Three reasons: