Headline
CVE-2021-42201: heap-buffer-overflow exists in the function swf_GetD64 in rfxswf.c · Issue #175 · matthiaskramm/swftools
An issue was discovered in swftools through 20201222. A heap-buffer-overflow exists in the function swf_GetD64() located in rfxswf.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
==8687==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x60b00000aff8 at pc 0x000000473b4e bp 0x7fffffffdc10 sp 0x7fffffffdc00
READ of size 8 at 0x60b00000aff8 thread T0
#0 0x473b4d in swf_GetD64 /test/swftools-asan/lib/rfxswf.c:520
#1 0x4a7851 in pool_read as3/pool.c:1119
#2 0x4935ec in swf_ReadABC as3/abc.c:748
#3 0x409045 in main /test/swftools-asan/src/swfdump.c:1577
#4 0x7ffff68a683f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2083f)
#5 0x40c168 in _start (/test/swftools-asan/src/swfdump+0x40c168)
0x60b00000affd is located 0 bytes to the right of 109-byte region [0x60b00000af90,0x60b00000affd)
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/lib/rfxswf.c:520 swf_GetD64
Shadow bytes around the buggy address:
0x0c167fff95a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff95b0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff95c0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff95d0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff95e0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c167fff95f0: fa fa 00 00 00 00 00 00 00 00 00 00 00 00 00[05]
0x0c167fff9600: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff9610: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff9620: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff9630: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c167fff9640: 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
==8687==ABORTING
POC
swf_GetD64_poc