Message-ID: <2920230.e42.15d924eeca0.Coremail.qflb.wu@dbappsecurity.com.cn>
Date: Sun, 30 Jul 2017 15:03:51 +0800 (GMT+08:00)
From: "qflb.wu" <qflb.wu@...ppsecurity.com.cn>
To: fulldisclosure@...lists.org
Subject: [FD] Links buffer over-read vulnerability

Links buffer over-read vulnerability
================
Author : qflb.wu
===============


Introduction:
=============
Links is a text and graphics mode WWW browser. It includes support for rendering tables and frames, features background downloads, can display colors and has many other features.


Affected version:
=====
2.14


Vulnerability Description:
==========================
the put_chars function in html_r.c in Links 2.14 can cause a denial of service(buffer over-read) via a crafted html file.


./links -dump links_2.14_buffer_over_read.html


=================================================================
==10690==ERROR: AddressSanitizer: global-buffer-overflow on address 0x000002303d00 at pc 0x667c5e bp 0x7ffca2e786f0 sp 0x7ffca2e786e8
READ of size 1 at 0x000002303d00 thread T0
    #0 0x667c5d in put_chars /home/a/Documents/links-2.14/html_r.c:662
    #1 0x635815 in put_chars_conv /home/a/Documents/links-2.14/html.c:725
    #2 0x5e92ec in put_chrs /home/a/Documents/links-2.14/html.c:764
    #3 0x5d23f0 in parse_html /home/a/Documents/links-2.14/html.c:2865
    #4 0x64814e in do_format /home/a/Documents/links-2.14/html_r.c:1015
    #5 0x64814e in format_html_part /home/a/Documents/links-2.14/html_r.c:1092
    #6 0x64c42b in really_format_html /home/a/Documents/links-2.14/html_r.c:1248
    #7 0x7e528e in format_html /home/a/Documents/links-2.14/session.c:1177
    #8 0x7e528e in cached_format_html /home/a/Documents/links-2.14/session.c:1420
    #9 0x73fe2a in end_dump /home/a/Documents/links-2.14/main.c:306
    #10 0x77a08e in object_timer /home/a/Documents/links-2.14/objreq.c:425
    #11 0x7beaf2 in check_timers /home/a/Documents/links-2.14/select.c:468
    #12 0x7bc09d in select_loop /home/a/Documents/links-2.14/select.c:890
    #13 0x73bdc9 in main /home/a/Documents/links-2.14/main.c:616
    #14 0x7f2765871ec4 (/lib/x86_64-linux-gnu/libc.so.6+0x21ec4)
    #15 0x48619c in _start (/home/a/Documents/links-2.14/links+0x48619c)


0x000002303d00 is located 0 bytes to the right of global variable 'put_chars_conv.buffer' from 'html.c' (0x2303c00) of size 256
SUMMARY: AddressSanitizer: global-buffer-overflow /home/a/Documents/links-2.14/html_r.c:662 put_chars
Shadow bytes around the buggy address:
  0x000080458750: 04 f9 f9 f9 f9 f9 f9 f9 04 f9 f9 f9 f9 f9 f9 f9
  0x000080458760: 01 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
  0x000080458770: 00 f9 f9 f9 f9 f9 f9 f9 04 f9 f9 f9 f9 f9 f9 f9
  0x000080458780: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x000080458790: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
=>0x0000804587a0:[f9]f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
  0x0000804587b0: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
  0x0000804587c0: 00 f9 f9 f9 f9 f9 f9 f9 00 f9 f9 f9 f9 f9 f9 f9
  0x0000804587d0: 00 f9 f9 f9 f9 f9 f9 f9 00 00 00 00 00 00 00 00
  0x0000804587e0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x0000804587f0: 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
  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
  ASan internal:         fe
==10690==ABORTING




POC:
links_2.14_buffer_over_read.html
CVE:
CVE-2017-11114




===============================




qflb.wu () dbappsecurity com cn
Download attachment "poc.zip" of type "application/x-zip-compressed" (1437 bytes)


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