Find sigma rule 
Attack: Process Injection: Asynchronous Procedure Call
Adversaries may inject malicious code into processes via the asynchronous procedure call (APC) queue in order to evade process-based defenses as well as possibly elevate privileges. APC injection is a method of executing arbitrary code in the address space of a separate live process.
APC injection is commonly performed by attaching malicious code to the APC Queue (Citation: Microsoft APC) of a process’s thread. Queued APC functions are executed when the thread enters an alterable state.(Citation: Microsoft APC) A handle to an existing victim process is first created with native Windows API calls such as OpenThread. At this point QueueUserAPC can be used to invoke a function (such as LoadLibrayA pointing to a malicious DLL).
A variation of APC injection, dubbed “Early Bird injection”, involves creating a suspended process in which malicious code can be written and executed before the process’ entry point (and potentially subsequent anti-malware hooks) via an APC. (Citation: CyberBit Early Bird Apr 2018) AtomBombing (Citation: ENSIL AtomBombing Oct 2016) is another variation that utilizes APCs to invoke malicious code previously written to the global atom table.(Citation: Microsoft Atom Table)
Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via APC injection may also evade detection from security products since the execution is masked under a legitimate process.
MITRE
Tactic
- defense-evasion
- privilege-escalation
technique
- T1055.004
Test : EarlyBird APC Queue Injection in Go
OS
- windows
Description:
Creates a process in a suspended state and calls QueueUserAPC WinAPI to add a UserAPC to the child process that points to allocated shellcode. ResumeThread is called which then calls NtTestAlert to execute the created UserAPC which then executes the shellcode. This technique allows for the early execution of shellcode and potentially before AV/EDR can hook functions to support detection.
- PoC Credit: (https://github.com/Ne0nd0g/go-shellcode#createprocesswithpipe)
- References:
- https://www.bleepingcomputer.com/news/security/early-bird-code-injection-technique-helps-malware-stay-undetected/
- https://www.ired.team/offensive-security/code-injection-process-injection/early-bird-apc-queue-code-injection
Executor
powershell