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Date: Wed, 7 Jun 2017 12:53:43 +0000
From: "Agostino Sarubbo" <ago@...too.org>
To: "oss-security@...ts.openwall.com" <oss-security@...ts.openwall.com>
Subject: ytnef: heap-based-buffer overflow in SwapWord (ytnef.c)
Description:
ytnef is Yeraze’s TNEF Stream Reader – for winmail.dat files.
The complete ASan output of the issue:
# ytnefprint $FILE
==22220==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x602000000038 at pc 0x7ff75139d8eb bp 0x7ffeed684ad0 sp 0x7ffeed684ac8
READ of size 1 at 0x602000000038 thread T0
#0 0x7ff75139d8ea in SwapWord /tmp/ytnef-1.9.2/lib/ytnef.c:153:28
#1 0x7ff75139d8ea in TNEFDateHandler /tmp/ytnef-1.9.2/lib/ytnef.c:682
#2 0x7ff7513b4b47 in TNEFParse /tmp/ytnef-1.9.2/lib/ytnef.c:1184:15
#3 0x7ff7513b39d3 in TNEFParseFile /tmp/ytnef-1.9.2/lib/ytnef.c:1042:10
#4 0x508814 in main /tmp/ytnef-1.9.2/ytnefprint/main.c:80:9
#5 0x7ff7504c978f in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
#6 0x419c38 in _start (/usr/bin/ytnefprint+0x419c38)
0x602000000038 is located 0 bytes to the right of 8-byte region [0x602000000030,0x602000000038)
allocated by thread T0 here:
#0 0x4cf7e0 in calloc /tmp/portage/sys-libs/compiler-rt-sanitizers-4.0.0/work/compiler-rt-4.0.0.src/lib/asan/asan_malloc_linux.cc:74
#1 0x7ff7513b472a in TNEFParse /tmp/ytnef-1.9.2/lib/ytnef.c:1154:12
#2 0x7ff7513b39d3 in TNEFParseFile /tmp/ytnef-1.9.2/lib/ytnef.c:1042:10
#3 0x508814 in main /tmp/ytnef-1.9.2/ytnefprint/main.c:80:9
#4 0x7ff7504c978f in __libc_start_main /tmp/portage/sys-libs/glibc-2.23-r3/work/glibc-2.23/csu/../csu/libc-start.c:289
SUMMARY: AddressSanitizer: heap-buffer-overflow /tmp/ytnef-1.9.2/lib/ytnef.c:153:28 in SwapWord
Shadow bytes around the buggy address:
0x0c047fff7fb0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fc0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fd0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7fe0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c047fff7ff0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c047fff8000: fa fa fd fa fa fa 00[fa]fa fa fa fa fa fa fa fa
0x0c047fff8010: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8020: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8030: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8040: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff8050: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
Addressable: 00
Partially addressable: 01 02 03 04 05 06 07
Heap left redzone: fa
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack after return: f5
Stack use after scope: f8
Global redzone: f9
Global init order: f6
Poisoned by user: f7
Container overflow: fc
Array cookie: ac
Intra object redzone: bb
ASan internal: fe
Left alloca redzone: ca
Right alloca redzone: cb
==22220==ABORTING
Affected version:
1.9.2
Fixed version:
N/A
Commit fix:
N/A
Credit:
This bug was discovered by Agostino Sarubbo of Gentoo.
CVE:
CVE-2017-9471
Reproducer:
https://github.com/asarubbo/poc/blob/master/00243-ytnef-heapoverflow-SwapWord
Timeline:
2017-03-27: bug discovered and reported to upstream
2017-05-24: blog post about the issue
2017-06-07: CVE assigned
Note:
This bug was found with American Fuzzy Lop.
Permalink:
https://blogs.gentoo.org/ago/2017/05/24/ytnef-heap-based-buffer-overflow-in-swapword-ytnef-c/
--
Agostino Sarubbo
Gentoo Linux Developer
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