Headline
CVE-2021-42195: heap-buffer-overflow exists in the function handleEditText in swfdump.c · Issue #174 · matthiaskramm/swftools
An issue was discovered in swftools through 20201222. A heap-buffer-overflow exists in the function handleEditText() located in swfdump.c. It allows an attacker to cause code Execution.
system info
Ubuntu x86_64, clang 6.0, swfdump (latest master a9d5082)
Command line
./src/swfdump -D @@
AddressSanitizer output
==44192==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60600000e8d3 at pc 0x000000410aca bp 0x7fffffffdee0 sp 0x7fffffffded0
READ of size 1 at 0x60600000e8d3 thread T0
#0 0x410ac9 in handleEditText /test/swftools-asan/src/swfdump.c:549
#1 0x408624 in main /test/swftools-asan/src/swfdump.c:1511
#2 0x7ffff68a683f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2083f)
#3 0x40c168 in _start (/test/swftools-asan/src/swfdump+0x40c168)
0x60600000e8d3 is located 0 bytes to the right of 51-byte region [0x60600000e8a0,0x60600000e8d3)
allocated by thread T0 here:
#0 0x7ffff6f02602 in malloc (/usr/lib/x86_64-linux-gnu/libasan.so.2+0x98602)
#1 0x532fa7 in rfx_alloc /test/swftools-asan/lib/mem.c:30
#2 0x541396 (/test/swftools-asan/src/swfdump+0x541396)
SUMMARY: AddressSanitizer: heap-buffer-overflow /test/swftools-asan/src/swfdump.c:549 handleEditText
Shadow bytes around the buggy address:
0x0c0c7fff9cc0: 00 00 00 00 00 00 02 fa fa fa fa fa 00 00 00 00
0x0c0c7fff9cd0: 00 00 00 fa fa fa fa fa 00 00 00 00 00 00 00 fa
0x0c0c7fff9ce0: fa fa fa fa 00 00 00 00 00 00 00 05 fa fa fa fa
0x0c0c7fff9cf0: 00 00 00 00 00 00 00 fa fa fa fa fa 00 00 00 00
0x0c0c7fff9d00: 00 00 00 fa fa fa fa fa 00 00 00 00 00 00 00 fa
=>0x0c0c7fff9d10: fa fa fa fa 00 00 00 00 00 00[03]fa fa fa fa fa
0x0c0c7fff9d20: 00 00 00 00 00 00 00 fa fa fa fa fa 00 00 00 00
0x0c0c7fff9d30: 00 00 00 fa fa fa fa fa 00 00 00 00 00 00 00 fa
0x0c0c7fff9d40: fa fa fa fa 00 00 00 00 00 00 00 fa fa fa fa fa
0x0c0c7fff9d50: 00 00 00 00 00 00 00 fa fa fa fa fa 00 00 00 00
0x0c0c7fff9d60: 00 00 00 fa fa fa fa fa 00 00 00 00 00 00 00 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
==44192==ABORTING
POC
handleEditText_poc