# Unpacking SmokeLoader
**Working on this** [**Sample**](https://malshare.com/sample.php?action=detail\&hash=5fc6f24d43bc7ca45a81d159291955d1)*.*
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## Static Analysis
This Sample' Strings indicates a packed binary, with the **`.pdb`** path and everything. let's debug this right away.
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## Dynamically Unpacking the Sample
**1→**
This Sample uses **Process Hollowing** to inject the unpacked payload into another mapped process *- that it spawns -* by **unmapping** sections of this process and **reallocate** the same sections to **write/inject** its malicious payload into. The process it hollows could be a legitimate one, or even it's own process, which is the case with this Sample. So we mainly set breakpoints on, ***`CreateProcessA()`/ `CreateProcessInternalW()`/ `WriteProcessMemory()`/ `NtUnmapViewOfSection()`/ `VirtualAllocEx()`:*** This Call is different from the regular ***`VirtualAlloc()`***, because it takes a **`hProcess`** to allocate memory into a remote process.
**2→**
Once Run we hit ***`CreateProcess()` / `CreateProcessInternalW()`*** with `smoke.exe` (The Same Process) as the newly spawned process. `smoke.exe` is spawned in a suspended state.
**3→**
Returning from the call, we hit ***`NtUnmapViewOfSection()`***, given the handle (**5c** in my case) to the new `smoke.exe` \[3\`] and it clears it out so the process memory no longer have an allocated region at address **`0x`*****`400000`*** \[3\`\`] .
**4→**
Continuing On we hit ***`VirtualAllocEx()`***, on `smoke.exe` \[4\`] to reallocate the same region of memory, now it exists as empty in the process memory\[4\`\`].
**5→**
Next we hit the call to ***`WriteProcessMemory()`***, with the parameters passed we see it's passing the starting memory address ***`0x400000`*** of the newly allocated region to the **PEB** as part of the process initialization. That means an executable has been written there already.
With a breakpoint at ***`NtWriteVirtualMemory()`***, we could inspect the write operation taking place.
**6→**
Now from the looks of it, that doesn't seem as the final payload at all, its very shellcod-y with one section, so we can make a good guess that this is the Shellcode used to unpack the final payload. But we got our first stage payload so we dump it out for further analysis.
Now we could debug this dump or look through the disassembly and figure out the obfuscation, anti-analysis techniques and everything. But as for now, we learned that the first stage payload was Injected into a remote process using Process Hollowing and it was pretty straightforward, for more details on this Injection Technique, Check [**Process Hollowing**](https://ghostinthehive.gitbook.io/ghostinthehive-as-a-ghost-in-the-hive/windows-internals/malware-evasion-through-injection-pt1#greater-than-process-hollowing-w-ntunmapviewofsection) from **The REM-Essentials Series**.
**That leaves us to the deep analysis part which we will not cover here.**
