Add FOR610 exam cheat sheets (tools, assembly, Windows APIs)
Three markdown cheat sheets for exam preparation: - 01-tools.md: All analysis tools with descriptions, platforms, book section refs, and key pipe chains - 02-assembly.md: x86/x64 registers, instructions, calling conventions, stack frames, control flow, anti-analysis patterns - 03-windows-apis.md: All Windows APIs by category with DLLs, malware use cases, and technique-to-API mapping table Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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# FOR610 Windows API Cheat Sheet
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## File Operations (kernel32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **CreateFileA/W** | Open or create a file handle | Read/write config files, drop payloads |
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| **ReadFile** | Read data from file | Read malware configuration |
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| **WriteFile** | Write data to file | Drop payloads, write config |
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| **DeleteFileA/W** | Delete a file | Remove traces |
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| **CopyFile** | Copy a file | Spread to new locations |
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| **FindFirstFile / FindNextFile** | Enumerate files in directory | Search for targets (ransomware) |
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| **GetTempPath** | Get temp directory path | Common malware staging location |
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| **GetFileSize** | Get file size in bytes | Check payload size |
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## Resource Operations (kernel32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **FindResourceW** | Locate embedded resource | Find embedded payload in PE |
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| **SizeofResource** | Get resource size | Determine payload size |
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| **LoadResource** | Load resource into memory | Access embedded data |
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| **LockResource** | Get pointer to resource data | Read resource content |
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**Pattern:** FindResource → SizeofResource → LoadResource → LockResource → CreateFile → WriteFile → CreateProcess (**dropper pattern**)
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## Process Operations (kernel32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **CreateProcessA/W** | Create new process | Launch cmd.exe, spawn child for hollowing |
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| **OpenProcess** | Get handle to existing process | Target process for injection |
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| **TerminateProcess** | Kill a process | Kill security tools |
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| **ExitProcess** | Terminate current process | Anti-debug: exit if detected |
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| **GetCurrentProcess** | Get own process handle | Self-inspection |
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## Process Enumeration (kernel32.dll / psapi.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **CreateToolhelp32Snapshot** | Snapshot of running processes | Find injection targets |
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| **Process32FirstW** | Get first process from snapshot | Begin enumeration |
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| **Process32NextW** | Get next process from snapshot | Continue enumeration |
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| **EnumProcesses** | List all process IDs | Alternative enumeration |
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**Pattern:** CreateToolhelp32Snapshot → Process32First → Process32Next (loop) → OpenProcess (**find target for injection**)
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## Memory Operations (kernel32.dll)
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| API | What it does | Malware use | Key params |
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|-----|-------------|-------------|-----------|
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| **VirtualAlloc** | Allocate memory in own process | Unpack code to new memory | flProtect: 0x40 = RWX |
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| **VirtualAllocEx** | Allocate memory in OTHER process | Injection: create space for shellcode | flProtect: 0x40 = PAGE_EXECUTE_READWRITE |
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| **VirtualProtect** | Change memory page protection | Make data executable after writing | 0x40 = RWX (suspicious!) |
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| **WriteProcessMemory** | Write to OTHER process memory | Inject shellcode/DLL into target |
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| **ReadProcessMemory** | Read from OTHER process memory | Steal data from other processes |
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| **VirtualFree** | Free allocated memory | Cleanup |
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## Thread Operations (kernel32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **CreateThread** | Create thread in own process | Execute shellcode in parallel |
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| **CreateRemoteThread** | Create thread in OTHER process | **Execute injected code** |
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| **ResumeThread** | Resume suspended thread | Wake up hollowed process |
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| **SuspendThread** | Pause a thread | Freeze target during injection |
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| **QueueUserAPC** | Queue async procedure call | APC injection technique |
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## DLL / Module Operations (kernel32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **LoadLibraryA/W** | Load DLL at runtime | DLL injection via CreateRemoteThread, load sideloaded DLL |
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| **GetProcAddress** | Get function address from DLL | Dynamically resolve APIs (avoid import table) |
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| **GetModuleHandleA/W** | Get handle to loaded DLL | **Detect security tools** (check for avghookx.dll, etc.) |
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| **FreeLibrary** | Unload DLL | Cleanup |
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## Registry Operations (advapi32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **RegOpenKeyExA/W** | Open registry key | Access persistence keys, read config |
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| **RegSetValueEx** | Set registry value | **Persistence** (Run keys), store config |
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| **RegQueryValueExA** | Read registry value | Read stored config/commands |
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| **RegCreateKeyEx** | Create new key | Set up persistence |
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| **RegDeleteValue** | Delete a value | Remove traces |
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**Persistence locations:**
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- `HKCU\Software\Microsoft\Windows\CurrentVersion\Run`
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- `HKLM\Software\Microsoft\Windows\CurrentVersion\Run`
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## Network — WinINet (wininet.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **InternetOpenA** | Initialize internet session | Set up HTTP C2 (set user-agent) |
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| **InternetConnectA** | Connect to server | Connect to C2 host:port |
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| **HttpOpenRequestA** | Create HTTP request | Build GET/POST for C2 |
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| **HttpSendRequestA** | Send HTTP request | **Send C2 beacon/data** |
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| **InternetReadFile** | Read server response | **Receive C2 commands** |
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| **InternetOpenUrlA** | Open URL directly | Direct download |
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**C2 Pattern:** InternetOpen → InternetConnect → HttpOpenRequest → HttpSendRequest → InternetReadFile
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## Network — Sockets (ws2_32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **socket** | Create network socket | Raw TCP/UDP C2 |
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| **connect** | Connect to remote host | Establish C2 connection |
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| **send** | Send data | Exfiltrate data, send commands |
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| **recv** | Receive data | Receive C2 instructions |
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## Network — Other
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| API | DLL | Malware use |
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|-----|-----|-------------|
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| **URLDownloadToFileA** | urlmon.dll | Download next stage to disk |
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| **WinHttpOpen** | winhttp.dll | Modern HTTPS C2 |
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## Cryptography (advapi32.dll)
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| API | What it does | Malware use |
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|-----|-------------|-------------|
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| **CryptAcquireContext** | Get crypto provider handle | Set up encryption |
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| **CryptCreateHash** | Create hash object | Hash data for integrity |
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| **CryptEncrypt** | Encrypt data | Protect C2 traffic, encrypt config |
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| **CryptDecrypt** | Decrypt data | **Decrypt config files** (brbconfig.tmp) |
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## Execution (shell32.dll / kernel32.dll)
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| API | DLL | Malware use |
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|-----|-----|-------------|
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| **ShellExecuteA/W** | shell32.dll | Run commands, open URLs, launch programs |
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| **WinExec** | kernel32.dll | Simple program execution |
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| **system** | msvcrt.dll | Execute shell command via cmd.exe |
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## Anti-Analysis / Detection
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| API | DLL | What it checks |
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|-----|-----|---------------|
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| **IsDebuggerPresent** | kernel32.dll | Returns non-zero if debugger attached |
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| **CheckRemoteDebuggerPresent** | kernel32.dll | Check if any debugger is present |
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| **NtQueryInformationProcess** | ntdll.dll | Query ProcessDebugPort, ProcessDebugFlags |
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| **GetTickCount** | kernel32.dll | System uptime — low = sandbox |
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| **QueryPerformanceCounter** | kernel32.dll | High-res timer — detect single-stepping |
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| **OutputDebugString** | kernel32.dll | If debugger present, no error returned |
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| **BlockInput** | user32.dll | Block keyboard/mouse during execution |
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## Injection-Specific (ntdll.dll)
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| API | What it does | Technique |
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|-----|-------------|-----------|
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| **NtUnmapViewOfSection** | Remove memory section | **Process hollowing** — gut the target |
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| **ZwUnmapViewOfSection** | Same as above (Zw prefix) | Process hollowing variant |
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| **NtWriteVirtualMemory** | Native WriteProcessMemory | Injection via native API |
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| **RtlCreateUserThread** | Native CreateRemoteThread | Injection via native API |
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## Hooks & Monitoring
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| API | DLL | Malware use |
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|-----|-----|-------------|
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| **SetWindowsHookExA** | user32.dll | Install mouse/keyboard hook — wait for user activity (anti-sandbox) |
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| **FindWindowW** | user32.dll | **Detect analysis tools** by window title (OLLYDBG, WinDbg, etc.) |
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## System Information
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| API | DLL | Malware use |
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|-----|-----|-------------|
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| **GetComputerName** | kernel32.dll | Fingerprint victim for C2 |
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| **GetUserName** | advapi32.dll | Identify logged-in user |
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| **Sleep** | kernel32.dll | Delay execution (anti-sandbox, C2 beacon interval) |
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| **SetFileTime** | kernel32.dll | Timestomp — hide file creation time |
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---
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## Quick Reference: API → Technique Mapping
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| If you see these APIs... | The malware is... |
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|--------------------------|-------------------|
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| VirtualAllocEx + WriteProcessMemory + CreateRemoteThread | **Code injection** |
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| CreateProcess(SUSPENDED) + NtUnmapViewOfSection + WriteProcessMemory + ResumeThread | **Process hollowing** |
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| LoadLibrary + GetProcAddress (in loop) | **Dynamic API resolution** (evasion) |
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| InternetOpen + HttpSendRequest + InternetReadFile | **HTTP C2 communication** |
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| FindResource + LoadResource + WriteFile + CreateProcess | **Resource dropper** |
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| RegOpenKeyEx + RegSetValueEx (Run keys) | **Persistence** |
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| CreateToolhelp32Snapshot + Process32First/Next | **Process enumeration** (find target) |
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| IsDebuggerPresent / NtQueryInformationProcess | **Anti-debugging** |
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| SetWindowsHookEx(WH_MOUSE_LL) | **Anti-sandbox** (wait for user) |
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| CryptDecrypt | **Config/payload decryption** |
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| GetModuleHandle("avghookx.dll") / FindWindow("OLLYDBG") | **Security tool detection** |
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---
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## DLL Quick Reference
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| DLL | Contains |
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| **kernel32.dll** | File, process, memory, thread, module operations |
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| **advapi32.dll** | Registry, crypto, services |
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| **ntdll.dll** | Native API (Nt/Zw functions — low-level) |
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| **user32.dll** | Windows/hooks/UI (SetWindowsHookEx, FindWindow, BlockInput) |
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| **ws2_32.dll** | Winsock — raw socket networking |
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| **wininet.dll** | High-level HTTP/HTTPS (InternetOpen, HttpSendRequest) |
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| **shell32.dll** | ShellExecute — run programs/URLs |
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| **urlmon.dll** | URLDownloadToFile |
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| **msvcrt.dll** | C runtime — system(), malloc() |
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