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220 lines
8.8 KiB
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220 lines
8.8 KiB
Markdown
# Anti-analysis
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- Anti-analysisに利用されるAPI,ファイル名，プロセス名，dll，レジストリ等の一覧まとめ<br>
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[Collection of Anti-Malware Analysis Tricks.(2016-10)](https://forum.tuts4you.com/topic/38931-collection-of-anti-malware-analysis-tricks/)
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## Injection/Hollowing
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- 正規プロセス等のアドレス空間にコードを注入することで検知や分析を妨害するTechnique
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- 利用される正規プロセス：svchost.exe,explorer.exe,regsvr32.exe等
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- Heaven's Gateと組み合わせて利用される場合あり
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- ref:
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- 各種Injection/Hollowingで利用されるAPIの一覧<br>
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[HUNTING PROCESS INJECTION BY WINDOWSAPI CALLS (2019-11)](https://malwareanalysis.co/wp-content/uploads/2019/11/Hunting-Process-Injection-by-Windows-API-Calls.pdf)<br>
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- 図で分かりやすく説明<br>
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[Ten Process Injection Techniques: A Technical Survey Of Common And Trending Process Injection Techniques](https://www.endgame.com/blog/technical-blog/ten-process-injection-techniques-technical-survey-common-and-trending-process)
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- プログラムベースの説明<br>
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[Code & Process Injection,Red Teaming Experiments](https://ired.team/offensive-security/code-injection-process-injection)
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### Dll Injection
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- 正規プロセス探索->プロセスのハンドル取得->メモリ領域確保->悪性DLL注入->実行
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- e.g. CreateToolhelp32Snapshot,Process32First,Process32Next->OpenProcess->VirtualAllocEx->WriteProcessMemory->CreateRemoteThread<br>
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[07b8f25e7b536f5b6f686c12d04edc37e11347c8acd5c53f98a174723078c365](https://www.virustotal.com/gui/file/07b8f25e7b536f5b6f686c12d04edc37e11347c8acd5c53f98a174723078c365/detection)
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### Thread Execution Hijacking
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- 正規プロセス，スレッド探索->スレッドのハンドル取得->スレッド停止->メモリ領域確保->悪性コード注入->EIP書き換え->実行
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- e.g. CreateToolhelp32Snapshot,Thread32First,Thread32Next->OpenThread->SuspendThread->VirtualAllocEx->WriteProcessMemory->SetThreadContext->ResumeThread
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[787cbc8a6d1bc58ea169e51e1ad029a637f22560660cc129ab8a099a745bd50e](https://www.virustotal.com/gui/file/787cbc8a6d1bc58ea169e51e1ad029a637f22560660cc129ab8a099a745bd50e/detection)
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### Dll Injection Using SetWindowsHookEx(Hook Injection)
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- Hooking:
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> Hooking is a technique used to intercept function calls.
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- SetWindowsHookEx
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> - The first argument is the type of event. The events reflect the range of hook types, and vary from pressing keys on the keyboard (WH_KEYBOARD) to inputs to the mouse (WH_MOUSE), CBT, etc.
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> - The second argument is a pointer to the function the malware wants to invoke upon the event execution.
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> - The third argument is a module that contains the function.
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> - The last argument to this function is the thread with which the hook procedure is to be associated.
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- dll読み込み->アドレス解決->正規プロセス，スレッドの探索->フック
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- e.g. LoadLibrary->GetProcAddress->CreateToolhelp32Snapshot,Thred32First,Thread32Next->SetWindowsHookEx
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[5d6ddb8458ee5ab99f3e7d9a21490ff4e5bc9808e18b9e20b6dc2c5b27927ba1](https://www.virustotal.com/gui/file/5d6ddb8458ee5ab99f3e7d9a21490ff4e5bc9808e18b9e20b6dc2c5b27927ba1/detection)
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### Process Hollowing
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- 正規プロセス作成(サスペンド状態)->空洞化->メモリ領域確保->悪性コード注入->エントリポイント設定->実行<br>
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- e.g. CreateProcess->ZwUnmapViewOfSection(NtUnmapViewOfSection)->VirtualAllocEx->WriteProcessMemory->SetThreadContext->ResumeThread<br>
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[eae72d803bf67df22526f50fc7ab84d838efb2865c27aef1a61592b1c520d144](https://www.virustotal.com/gui/file/eae72d803bf67df22526f50fc7ab84d838efb2865c27aef1a61592b1c520d144/detection)
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### APC Injection
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- プロセス，スレッド探索->アラート状態->ハンドル取得->キューに追加
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- e.g. Createtoolhelp32Snapshot,Thread32First,Thread32Next->WaitForMultipleObjectEx->OpenThread->VirtualAllocEx->WriteProcessMemory->QueueUserAPC
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- QueueUserAPC
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> - First args: a handle to the target thread
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> - Second args: a pointer to the function that the malware wants to run
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> - Third args: the parameter that is passed to the function pointer.
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[f74399cc0be275376dad23151e3d0c2e2a1c966e6db6a695a05ec1a30551c0ad](https://www.virustotal.com/gui/file/f74399cc0be275376dad23151e3d0c2e2a1c966e6db6a695a05ec1a30551c0ad/detection)
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### ATOM BOMBING
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to do...
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### Shell Tray Window Injection
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to do...
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### Shim Injection
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to do...
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### IAT and Inline Hooking
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to do...
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### ALPC Injection
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to do...
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### REFLECTIVE PE Injection
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to do...
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### LOCKPOS
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to do...
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### KERNEL CALLBACK TABLE
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to do...
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### CLIPBRDWNDCLASS
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to do...
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### PROGATE
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to do...
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### EARLY BIRD
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to do...
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### CONSOLE WINDOW CLASS
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to do...
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### TOOLTIP Process Injection
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to do...
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### 永続化
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- **Applnit_Dlls**<br>
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to do...
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- **AppCertDlls**<br>
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to do...
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- **IFEO**<br>
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to do...
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## Heaven's Gate
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- 0x33セグメントセレクターを使用して32ビット（WOW64）プロセスで64ビットコードを実行するTechnique<br>
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- x86用ユーザモードデバッガでの追跡が難しい<br>
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- WinDBG等のカーネルモードデバッガでは追跡することができる<br>
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- 名前の由来はVX Heavenに投稿されたから<br>
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- 少なくともtrickbot,locky,emotet等では利用されていた<br>
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- ref:<br>
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[Knockin’ on Heaven’s Gate – Dynamic Processor Mode Switching(2012-09)](http://rce.co/knockin-on-heavens-gate-dynamic-processor-mode-switching/)<br>
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[The 0x33 Segment Selector (Heavens Gate)](https://www.malwaretech.com/2014/02/the-0x33-segment-selector-heavens-gate.html)<br>
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## API obfuscation
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[A Museum of API Obfuscation on Win32](http://eval.symantec.com/mktginfo/enterprise/media/security_response/whitepapers/a_museum_of_api_obfuscation_on_win32.pdf)<br>
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## PowerShell Script obfuscation
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- 難読化ツール<br>
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[Invoke-Obfuscation](https://github.com/danielbohannon/Invoke-Obfuscation)
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- Powershell Script内で用いられる難読化技術について
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### Case-insensitive
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- コマンドレッ名や変数名に大文字，小文字を混ぜる
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- PowerShellでは区別されない
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```
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INvOke-eXpReSsiOn
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```
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### Alias
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- コマンドのエイリアスを用いる
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- エイリアスの確認方法
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```
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get-alias # すべてのエイリアスの確認<br>
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get-alias iex #iexのエイリアス(Invoke-Expression)の確認
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```
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- よく利用されるエイリアス
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```
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iex -> Invoke-Expression
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sal -> Set-Alias
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```
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- エイリアスの設定
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```
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set-alias <Name> <Value>
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sal ping iex
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```
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### Dot expression and amp expression(Invoke-Expression)
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- 文字列で表現されたコマンドレットを実行
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```
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.("get-alias")
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&('gal')
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iex("GeT-AliAs")
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```
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### Combining characters
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- 文字や文字列の結合
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```
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'i'+'ex'
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```
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### Backticks
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- コマンドレットや変数にバッククォートを挿入
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```
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`i`e`x("`gal `gal")
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```
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### Split method
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- 文字列の分割
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```
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'bob@alice'-split('@') -> bob alice
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'bob@alice' -split '@' -split "i" -> bob al ce
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```
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### Join method
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- リストの結合
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```
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"bob","alice" -join "@" -> bob@alice
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```
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### Concatenation operations
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- 文字列の並べ替えおよび連結
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```
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"{1} {0}" -f "Alice","Bob" -> Bob Alice
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"{1} {0}" -f "Alice",("{1}{2}{0}" -f "b","B","o") -> Bob Alice
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```
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### No Space
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- 空白の省略
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```
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"bob","alice"-join"@"
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```
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### Pipe operator
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- パイプによる引数の引き渡し
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```
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'Write-host 1' | iex
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```
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### $ENV variable
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- 環境変数の値を文字列の作成等に利用
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```
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.($seLLId[1]+$shEllId[13]+'x') -> .(iex)
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&($EnV:cOmSpEc[4,15,25]-JOIN'') -> &(iex)
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```
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### Encode
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- xor
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- 文字，16進数，10進数等で指定可能
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```
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10-bxor"10" -> 0
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"0xa"-bxor10 -> 0
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```
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- base64
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```
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[System.Convert]::FromBase64String("Ym9iYWxpY2UK") -> bobalice
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```
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- zlib
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```
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New-Object System.IO.Compression.DeflateStream([iO.mEmoRySTream] [sysTEM.ConVert]::frOMBASE64STrING("Ym9iYWxpY2UK"))
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```
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- unicode
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```
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[System.Text.Encoding]::Unicode.GetString($unicodeBytes)
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```
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### Ascii code
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- 文字などをasciiコードの10進数，16進数表記で示す
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```
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[string][char[]](0x69,0x65,0x58) -> i e X
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```
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### Replace method
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- 文字や文字列を置換する
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```
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'i e x'-replace ' ','' -> ieX
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```
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### %(foreach-object)
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- foreach-objectの省略系で%を利用
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```
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((0x69, 0x65, 0x58) | %{([char] [int] $_)})-jOIN'' -> ieX
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```
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### Comment out
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- コメントアウト
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```
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<#bobalice#>
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```
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### ref:
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[Powershell Static Analysis & Emotet results](https://hatching.io/blog/powershell-analysis)
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# Anti-detection
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## DGA
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- ドメイン生成アルゴリズム<br>
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- 数学的なアルゴリズムを利用して一定間隔ごとに異なる通信先ドメインを生成することにより，ドメイン名での検知を困難にする<br>
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- 43ファミリのDGAに対してseedタイプ，DGAタイプ，エントロピー，TLD等様々な観点から比較<br>
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[A Comprehensive Measurement Study of Domain Generating Malware,USENIX2016](https://www.usenix.org/conference/usenixsecurity16/technical-sessions/presentation/plohmann)
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