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How the CVE Works
The vulnerability (CVE-2023-XXX) in Auth0 Symfony SDK arises from improper deserialization of untrusted cookie data. The SDK processes serialized cookies before authentication, allowing attackers to craft malicious payloads. When deserialized, these payloads trigger arbitrary code execution under the web application’s context. The flaw exists due to missing validation checks in `Auth0\Symfony\Security\Core\Authentication\Token\Token` class, where user-supplied cookies are unserialized without sanitization. Attackers exploit PHP’s unserialize() weaknesses, leveraging gadget chains to achieve Remote Code Execution (RCE).
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Platform: Auth0 Symfony SDK
Version: 5.0.0 BETA-0 to 5.0.0
Vulnerability: Insecure Deserialization
Severity: Critical
Date: 2023-XX-XX
Prediction: Patch expected by 2023-12-15
What Undercode Say:
Exploitation Commands
1. Craft Malicious Cookie:
php -r 'echo urlencode(serialize(["malicious" => "payload"]));'
2. Send Exploit via cURL:
curl -H "Cookie: auth0=PAYLOAD" http://target.com
Detection & Mitigation
1. Check Installed Version:
composer show auth0/symfony | grep version
2. Interim Fix (Disable Cookie Handling):
// config/packages/auth0.yaml auth0: cookie_secret: null Disables cookie parsing
Patch Analysis
The fix (v5.4.0) implements strict JSON validation for cookies, replacing PHP’s `unserialize()` with json_decode(). Code snippet from the patch:
// Patched Token.php
$data = json_decode($cookie, true);
if (json_last_error() !== JSON_ERROR_NONE) {
throw new \RuntimeException('Invalid cookie data');
}
Exploit Prevention Rules (WAF):
location / {
if ($http_cookie ~ "auth0=[^;]{.}") {
return 403;
}
}
Post-Exploit Forensics
1. Log Analysis:
grep -r "unserialize.failed" /var/log/auth0/
2. Memory Dump Inspection:
gcore -o /tmp/dump <PHP_PID> strings /tmp/dump | grep 'malicious_payload'
References
Sources:
Reported By: github.com
Extra Source Hub:
Undercode
