Home / exploits Windows SpoolFool Privilege Escalation
Posted on 16 March 2022
The Windows Print Spooler has a privilege escalation vulnerability that can be leveraged to achieve code execution as SYSTEM. The SpoolDirectory, a configuration setting that holds the path that a printer's spooled jobs are sent to, is writable for all users, and it can be configured via SetPrinterDataEx() provided the caller has the PRINTER_ACCESS_ADMINISTER permission. If the SpoolDirectory path does not exist, it will be created once the print spooler reinitializes. Calling SetPrinterDataEx() with the CopyFiles registry key will load the dll passed in as the pData argument, meaning that writing a dll to the SpoolDirectory location can be loaded by the print spooler. Using a directory junction and UNC path for the SpoolDirectory, the exploit writes a payload to C:WindowsSystem32spooldriversx644 and loads it by calling SetPrinterDataEx(), resulting in code execution as SYSTEM.
