Sub-technique of T1055 Process Injection.View on attack.mitre.org
Adversaries may inject malicious code into suspended and hollowed processes in order to evade process-based defenses. Process hollowing is a method of executing arbitrary code in the address space of a separate live process.
Process hollowing is commonly performed by creating a process in a suspended state then unmapping/hollowing its memory, which can then be replaced with malicious code. A victim process can be created with native Windows API calls such as CreateProcess, which includes a flag to suspend the processes primary thread. At this point the process can be unmapped using APIs calls such as ZwUnmapViewOfSection or NtUnmapViewOfSection before being written to, realigned to the injected code, and resumed via VirtualAllocEx, WriteProcessMemory, SetThreadContext, then ResumeThread respectively.
This is very similar to Thread Local Storage but creates a new process rather than targeting an existing process. This behavior will likely not result in elevated privileges since the injected process was spawned from (and thus inherits the security context) of the injecting process. However, execution via process hollowing may also evade detection from security products since the execution is masked under a legitimate process.
Rules on DetectionCode tagged with T1055.012.
| Rule | Level | Log source |
|---|---|---|
| HackTool - CACTUSTORCH Remote Thread Creation | high | windows / create_remote_thread |
| HackTool - HollowReaper Execution | high | windows / process_creation |
| Uncommon Svchost Command Line Parameter | high | windows / process_creation |
| Potential Process Hollowing Activity | medium | windows / process_tampering |
| Rule | Type | Risk | Data source |
|---|---|---|---|
| PowerShell PInvoke Process Injection API Chain | TTP | NULL | Powershell Script Block Logging 4104 |
None recorded.
| Used by | Procedure example |
|---|---|
| GroupAPT-C-36 | APT-C-36 has used process hollowing to execute malware in the memory of legitimate processes. |
| GroupBlackByte | BlackByte used process hollowing for defense evasion purposes. |
| GroupGorgon Group | Gorgon Group malware can use process hollowing to inject one of its trojans into another process. |
| GroupKimsuky | Kimsuky has used a file injector DLL to spawn a benign process on the victim's system and inject the malicious payload into it via process hollowing. |
| GroupmenuPass | menuPass has used process hollowing in iexplore.exe to load the RedLeaves implant. |
| GroupPatchwork | A Patchwork payload uses process hollowing to hide the UAC bypass vulnerability exploitation inside svchost.exe. |
| GroupTA2541 | TA2541 has used process hollowing to execute CyberGate malware. |
| GroupThreat Group-3390 | A Threat Group-3390 tool can spawn `svchost.exe` and inject the payload into that process. |
| Used by | Procedure example |
|---|---|
| MalwareAgent Tesla | Agent Tesla has used process hollowing to create and manipulate processes through sections of unmapped memory by reallocating that space with its malicious code. |
| MalwareAstaroth | Astaroth can create a new process in a suspended state from a targeted legitimate process in order to unmap its memory and replace it with malicious code. |
| MalwareAzorult | Azorult can decrypt the payload into memory, create a new suspended process of itself, then inject a decrypted payload to the new process and resume new process execution. |
| MalwareBADNEWS | BADNEWS has a command to download an .exe and use process hollowing to inject it into a new process. |
| MalwareBandook | Bandook has been launched by starting iexplore.exe and replacing it with Bandook's payload. |
| MalwareBazar | Bazar can inject into a target process including Svchost, Explorer, and cmd using process hollowing. |
| MalwareBBSRAT | BBSRAT has been seen loaded into msiexec.exe through process hollowing to hide its execution. |
| MalwareCaminho | Caminho has launched and hollowed out MSBuild.exe to host malicious code. |
Data from MITRE ATT&CK® (Enterprise). ATT&CK® is a registered trademark of The MITRE Corporation.
