Closed
Description
Description
Whilst experimenting with htmldoc, built from commit 31f7804, we are able to induce a vulnerability in function pdf_write_names , using a harness compiled from htmldoc/htmldoc.cxx.
Because there is no bounds checking, a heap-based out-of-bound read will be triggered when the software encounters a malformed file, result in information disclosure or denial of service.
Proof of Concept
The POC is: poc_heap_overflow1
The command is: `./htmldoc --webpage -t pdf -f /dev/null poc_heap_overflow1
The ASAN report is:
=================================================================
==50540==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6250000020f4 at pc 0x0000003cf241 bp 0x7fffffffaf90 sp 0x7fffffffaf88
READ of size 4 at 0x6250000020f4 thread T0
#0 0x3cf240 in pdf_write_names(_IO_FILE*) /work/libraries/htmldoc/htmldoc/ps-pdf.cxx:3589:39
#1 0x3cf240 in pdf_write_document(unsigned char*, unsigned char*, unsigned char*, unsigned char*, unsigned char*, unsigned char*, tree_str*, tree_str*) /work/libraries/htmldoc/htmldoc/ps-pdf.cxx:2301:5
#2 0x3cf240 in pspdf_export /work/libraries/htmldoc/htmldoc/ps-pdf.cxx:910:7
#3 0x39a254 in main /work/libraries/htmldoc/htmldoc/htmldoc.cxx:1291:3
#4 0x7ffff75070b2 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x270b2)
#5 0x2a051d in _start (/work/libraries/htmldoc/htmldoc/htmldoc+0x2a051d)
0x6250000020f4 is located 20 bytes to the right of 8160-byte region [0x625000000100,0x6250000020e0)
allocated by thread T0 here:
#0 0x31b6f9 in realloc (/work/libraries/htmldoc/htmldoc/htmldoc+0x31b6f9)
#1 0x3ddaf8 in check_pages(int) /work/libraries/htmldoc/htmldoc/ps-pdf.cxx:8859:24
SUMMARY: AddressSanitizer: heap-buffer-overflow /work/libraries/htmldoc/htmldoc/ps-pdf.cxx:3589:39 in pdf_write_names(_IO_FILE*)
Shadow bytes around the buggy address:
0x0c4a7fff83c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c4a7fff83d0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c4a7fff83e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c4a7fff83f0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
0x0c4a7fff8400: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0c4a7fff8410: 00 00 00 00 00 00 00 00 00 00 00 00 fa fa[fa]fa
0x0c4a7fff8420: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4a7fff8430: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4a7fff8440: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4a7fff8450: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
0x0c4a7fff8460: 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
Shadow gap: cc
==50540==ABORTING
Impact
This vulnerability is capable of inducing information disclosure or denial of service.