Playing Malware Injection with Exploit thoughts

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Playing Malware Injection with Exploit thoughts [email protected]

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• Master degree at CSIE, NTUST • Security Researcher - chrO.ot, TDOHacker • Speaker - BlackHat, VXCON, HITCON >_cat ./Bio

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• Introduction • Challenge When we meet Anti-Virus • Interesting Case - PowerLoader since 2013 • New Vulnerability - 3 idea inspired by PowerLoader • Summary >_ls ./agenda

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[email protected] Quickly Review: What's Malware Injection?

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>_man inject (｀_´)ゞ Used for bypassing whitelist checking, byassing anti-virus, privilege escalation, etc. e.g. • DLL Side-Loading + Digital Signature = Bypassing anti-virus • Remote Inject + whitelisted process = Bypassing whitelist • Inject explorer + DLL Side-Loading + Self-elevate Service  = Bypassing Windows UAC (User Account Control) *Vista ~ Win8*

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>_man inject There're serval well-known techniques • Shellcode Inject or DLL Inject - OpenProcess, VirtualAllocExRWX, WriteProcessMemory, CreateRemoteThread  • Process Hollowing (aka RunPE) - OpenProcess, CreateProcessASuspended, Mapping PE FileVirtualAllocEx + WriteProcessMemory, GetThreadContext, and ResumeThread to Execute exe file from memory  • Thread Hijack or AtomBombing - QueueUserAPC, Inline Hook, or IAT Hijack  • Memory Exploit (PowerLoaderEX) - SetWindowLong, SendNotifyMessage

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(ꐦ`•ω•´)!!! Here are the 4 primary challenges that you'll encounter during injection. >_man inject

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There are 4 primary challenges in injection: 1. What's target - choose a target to inject, and it should be meaningful. e.g. explorer, svchost  2. Where to place - find memory for us to place RWX memory or ROPChain payload. e.g. VirtualAllocEx  3. How to inject payload - any way for us to write payload into remote process memory  4. How to execute - create a new thread to execute or hijack current thread of that process? >_man inject

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[email protected] Interesting Case: Powerloader since 2013

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Powerloader, aka Extra Window Vulnerability

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>_Shell_TrayWnd?

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>_Shell_TrayWnd? Window event callback function

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>_s_WndProc?

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>_s_WndProc?

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>_how it works Explorer Process Memory Low Address ➔ High Address ➔ Shell_TrayWnd Window Class Structure +0 - 0xcafe (vtable) +4 - window hwnd ...

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Explorer Process Memory Shell_TrayWnd +0 - 0xcafe (vtable) +4 - window hwnd ... vtable @ 0xcafe +0 - Interlocked (inc) +4 - message callback +8 - Interlocked (inc) >_how it works

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Explorer Process Memory Shell_TrayWnd +0 - 0xcafe (vtable) +4 - window hwnd ... vtable @ 0xcafe +0 - Interlocked (inc) +4 - message callback +8 - Interlocked (inc) Operating System 1) Send Window Message 2) Send Window Message 3) Invoke s_wndProc function 4) Invoke several function from vtable >_how it works

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Explorer Process Memory Shell_TrayWnd +0 - 0xcafe (vtable) +4 - window hwnd ... vtable @ 0xcafe +0 - Interlocked (inc) +4 - message callback +8 - Interlocked (inc) >_issue? GetWindowLong()

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Explorer Process Memory Shell_TrayWnd +0 - 0xbeef 0xcafe +4 - window hwnd ... >_issue? GetWindowLong() vtable @ 0xcafe +0 - Interlocked (inc) +4 - message callback +8 - Interlocked (inc) fake vtable @ 0xbeef +0 - shellcode addr +4 - shellcode ... SetWindowLong()

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Explorer Process Memory malicious Shell_TrayWnd >_issue? GetWindowLong() payload SetWindowLong() +0 - fake vtable ($+4) fake vtable +4 - shellcode addr ($+8) +8 - shellcode pwn!

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>_abuse vtable

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>_abuse vtable

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[email protected] Demo

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[email protected] 3 more vulnerability: From Exploit to Inject

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Actually, Many old-design services in Windows don't have vtable mitigation (° ꈊ °)✧˖

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[email protected] #1 Ole32 DropEnter Event

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>_cat ./ole32_init

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>_cat ./reg_dropevent

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>_man LPDROPTARGET IDropTarget actually is a virtual method table :)

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>_issue? vtable addr is determined by GetProp() so... it's really easy for us to hijack vtable just by SetProp() This callback function is used to deal with dropping file to Start Button of Explorer.exe

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>_how it works explorer Process Memory Low Address ➔ High Address ➔ DropTarget @ 0xc0fee DropTarget Structure +4 - function 1 ... +8 - function 2 +0C- dropfile func Prop Name Value OleDropTargetInterface 0xc0fee write DropTarget structure address (0xc0fee) via SetPropW() in function explorer!RegisterDragDrop +0 - 0xc0fee (this)

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>_how it works explorer Process Memory DropTarget @ 0xc0fee Prop Name Value OleDropTargetInterface 0xbeef payload @ 0xbeef +0 - 0xbeef (this) +4 - don't care ... +8 - don't care +0C- shellcode addr it's easy for us to change the return value of GetPropW("OleDropTargetInterface") from 0xc0fee to 0xbeef (malicious payload).

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explorer Process Memory Operating System 1) Send Window Message (Drag & Drop) 2) GetPropW("OleDropTargetInterface") 3) Invoke drop file function from vtable, invoke shellcode addr = *(beef+0c) >_how it works DropTarget @ 0xc0fee payload @ 0xbeef +0 - 0xbeef (this) +4 - don't care ... +8 - don't care +0C- shellcode addr Prop Name Value OleDropTargetInterface 0xbeef

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>_abuse vtable

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>_abuse vtable

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[email protected] Demo

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[email protected] #2 Comctl32 SubClass Event

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>_cat FastGetSubclsHdr

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>_cat MstSubclsProc

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>_cat EnterSubclsFram

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>_cat CallNxtSubclsProc

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>_cat EntrSubclsCallbk

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>_abuse vtable

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>_abuse vtable

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>_abuse vtable

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[email protected] Demo

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[email protected] #3 Thread Hijacking (win10+)

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3) create first thread of this process, point register eax to AddressOfEntry, point ebx+8 (TIB base + 8) to image base, and point eip to ntdll!LdrInitializeThunk Process >_Process? Kernel (ring0) Application (ring3) 1) create process via CreateProcess() 2) mapping file into memory iexplorer.exe .data section .text section AddressOfEntry ntdll.dll kernel32.dll ...

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>_Process? Process iexplorer.exe ntdll.dll kernel32.dll ... Call Stack -------------- _LdrpSnapModule _LdrpMapAndSnapDependency _LdrpMapDllWithSectionHandle _LdrpLoadKnownDll _LdrpFindOrPrepareLoadingModule _LdrpLoadDllInternal _LdrpLoadDll _LdrLoadDll _LdrpInitializeProcess __LdrpInitialize _LdrInitializeThunk fix import address table, fix export directory, apply relocation, etc .text section ntdll!LdrInitializeThunk

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>_Process? ntdll!LdrInitializeThunk [email protected] Process iexplorer.exe .text section ntdll.dll kernel32.dll ... ntdll!RtlUserThreadStart RtlUserThreadStart is entry-point of every thread. We can hijack thread via write shellcode address into global variable ‘LdrDelegatedRtlUserThreadStart'.

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3) point 'LdrDelegatedRtlUserThreadStart' to shellcode address Process >_Abuse Malware 1) get privilege of target process via OpenProcess() 2) mapping shellcode into target process chrome.exe .data section .text section shellcode ... ntdll.dll LdrDelegatedRtlUserThreadStart 4) every new thread of target process can be hijack to invoke shellcode