Sub-technique of T1547 Boot or Logon Autostart Execution.View on attack.mitre.org
Adversaries may abuse print processors to run malicious DLLs during system boot for persistence and/or privilege escalation. Print processors are DLLs that are loaded by the print spooler service, `spoolsv.exe`, during boot.
Adversaries may abuse the print spooler service by adding print processors that load malicious DLLs at startup. A print processor can be installed through the AddPrintProcessor API call with an account that has SeLoadDriverPrivilege enabled. Alternatively, a print processor can be registered to the print spooler service by adding the HKLM\SYSTEM\\[CurrentControlSet or ControlSet001]\Control\Print\Environments\\[Windows architecture: e.g., Windows x64]\Print Processors\\[user defined]\Driver Registry key that points to the DLL.
For the malicious print processor to be correctly installed, the payload must be located in the dedicated system print-processor directory, that can be found with the GetPrintProcessorDirectory API call, or referenced via a relative path from this directory. After the print processors are installed, the print spooler service, which starts during boot, must be restarted in order for them to run.
The print spooler service runs under SYSTEM level permissions, therefore print processors installed by an adversary may run under elevated privileges.
Rules on DetectionCode tagged with T1547.012.
| Rule | Type | Risk | Data source |
|---|---|---|---|
| Print Processor Registry Autostart | TTP | NULL | Sysmon EventID 13 |
| Print Spooler Adding A Printer Driver | TTP | NULL | Windows Event Log Printservice 316 |
| Print Spooler Failed to Load a Plug-in | TTP | NULL | Windows Event Log Printservice 808, Windows Event Log Printservice 4909 |
| Spoolsv Spawning Rundll32 | TTP | NULL | Sysmon EventID 1, Windows Event Log Security 4688, CrowdStrike ProcessRollup2 |
| Spoolsv Suspicious Loaded Modules | TTP | NULL | Sysmon EventID 7 |
| Spoolsv Writing a DLL | TTP | NULL | Sysmon EventID 1 AND Sysmon EventID 11, Windows Event Log Security 4688 AND Sysmon EventID 11 |
| Spoolsv Writing a DLL - Sysmon | TTP | NULL | Sysmon EventID 11 |
None recorded.
| Used by | Procedure example |
|---|---|
| GroupEarth Lusca | Earth Lusca has added the Registry key `HKLM\SYSTEM\ControlSet001\Control\Print\Environments\Windows x64\Print Processors\UDPrint” /v Driver /d “spool.dll /f` to load malware as a Print Processor. |
| Used by | Procedure example |
|---|---|
| MalwareGelsemium | Gelsemium can drop itself in |
| MalwarePipeMon | The PipeMon installer has modified the Registry key |
Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.
