CVE-2020-1472 PoC — Netlogon Elevation of Privilege Vulnerability

Source

https://github.com/CanciuCostin/CVE-2020-1472

Associated Vulnerability

Title:Netlogon Elevation of Privilege Vulnerability (CVE-2020-1472)
Description:An elevation of privilege vulnerability exists when an attacker establishes a vulnerable Netlogon secure channel connection to a domain controller, using the Netlogon Remote Protocol (MS-NRPC). An attacker who successfully exploited the vulnerability could run a specially crafted application on a device on the network. To exploit the vulnerability, an unauthenticated attacker would be required to use MS-NRPC to connect to a domain controller to obtain domain administrator access. Microsoft is addressing the vulnerability in a phased two-part rollout. These updates address the vulnerability by modifying how Netlogon handles the usage of Netlogon secure channels. For guidelines on how to manage the changes required for this vulnerability and more information on the phased rollout, see How to manage the changes in Netlogon secure channel connections associated with CVE-2020-1472 (updated September 28, 2020). When the second phase of Windows updates become available in Q1 2021, customers will be notified via a revision to this security vulnerability. If you wish to be notified when these updates are released, we recommend that you register for the security notifications mailer to be alerted of content changes to this advisory. See Microsoft Technical Security Notifications.

Description

CVE-2020-1472 - Zero Logon vulnerability Python implementation

Readme

![Python][python-shield]

# CVE-2020-1472

CVE-2020-1472 - Zero Logon vulnerability Python implementation

## Description

* A Python script which uses the Impacket library to test for CVE-2020-1472 - Zerologon vulnerability (credits to Secura research).
* The flaw stems from the Netlogon Remote Protocol, available on Windows domain controllers, which is used for various tasks related to user and machine authentication.
* Specifically, the issue exists in the usage of AES-CFB8 encryption for Netlogon sessions. The AES-CFB8 standard requires that each “byte” of plaintext have a randomized initialization vector (IV), blocking attackers from guessing passwords. However, Netlogon’s ComputeNetlogonCredential function sets the IV to a fixed 16 bits – not randomized –  meaning an attacker could control the deciphered text.
* "Due to incorrect use of an AES mode of operation it is possible to spoof the identity of any computer account (including that of the [Domain Controller] itself) and set an empty password for that account in the domain,” according to Secura researchers.

![Description](https://media.threatpost.com/wp-content/uploads/sites/103/2020/09/15102209/microsoft-window-attack.png)

* The script attempts to perform Netlogon authentication bypass. The script will terminate when succesfully 
performing the bypass.
* When a domain controller is patched, the script will stop after sending 2000 pairs of RPC calls (target is not vulnerable with a false negative chance of 0.04%).
* Note that by default this changes the password of the domain controller account. This allows to DCSync, but it also breaks communication with other DCs.
* More info and original research [here](https://www.secura.com/blog/zero-logon)

## Prerequisites

```
pip install impacket
```
or Download the impacket release [here](https://github.com/SecureAuthCorp/impacket/releases). Unpack it, and in the directory where you placed it, run:
```
pip install .
```

## Usage

Given a domain controller named `DC-NAME` with IP address `X.X.X.X`, run the script as follows:

    python cve-2020-1472.py DC-NAME X.X.X.X

The DC name is the NetBIOS computer name. If this name is not correct, the script will fail with a 
`STATUS_INVALID_COMPUTER_NAME` error.

[python-shield]: https://img.shields.io/badge/python-3.6-green

File Snapshot


 [4.0K]  /data/pocs/1c5cd28d963586446eabec5fd27af08e5f201f9b
├── [3.1K]  cve-2020-1472.py
└── [2.3K]  README.md

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