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ipfilter-overflow.txt

Posted on 24 May 2009
Source : packetstormsecurity.org Link

 

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[ IPFilter (ippool) 4.1.31 lib/load_http.c buffer overflow ]

Author: Maksymilian Arciemowicz
http://SecurityReason.com/

Date:
- - Dis.: 05.03.2009
- - Pub.: 22.05.2009

CVE: CVE-2009-1476
Risk: Low

Original URL:
http://securityreason.com/achievement_securityalert/62

- --- 0.Description ---
IPFilter is a software package that can be used to provide network
address translation (NAT) or firewall services. To use, it can either be
used as a loadable kernel module or incorporated into your UNIX kernel;
use as a loadable kernel module where possible is highly recommended.
Scripts are provided to install and patch system files, as required.

ippool - user interface to the IPFilter pools

Ippool is used to manage information stored in the IP pools subsystem of
IPFilter. Configuration file information may be parsed and loaded into
the kernel, currently configured pools removed or changed as well as
inspected.

- --- 1. IPFilter (ippool) 4.1.31 lib/load_http.c buffer overflow ---
The main problem exist in lib/load_http.c .

Let's see lib/load_http.c ( char buffer[1024] )

- ---
...
alist_t *
load_http(char *url)
{
int fd, len, left, port, endhdr, removed;
char *s, *t, *u, buffer[1024], *myurl;
alist_t *a, *rtop, *rbot;
struct sockaddr_in sin;
struct hostent *host;

/*
* More than this would just be absurd.
*/
if (strlen(url) > 512) {
fprintf(stderr, "load_http has a URL > 512 bytes?!
");
return NULL;
}

fd = -1;
rtop = NULL;
rbot = NULL;

sprintf(buffer, "GET %s HTTP/1.0
", url);

myurl = strdup(url);
if (myurl == NULL)
goto done;

s = myurl + 7; /* http:// */
t = strchr(s, '/');
if (t == NULL) {
fprintf(stderr, "load_http has a malformed URL '%s'
", url);
free(myurl);
return NULL;
}
*t++ = '';

u = strchr(s, '@');
if (u != NULL)
s = u + 1; /* AUTH */

sprintf(buffer + strlen(buffer), "Host: %s

", s);
...
- ---

0. buffer[] have only 1024 bytes,
1. url can't have more than 512 bytes,
2. url will be copied into buffer here:

sprintf(buffer, "GET %s HTTP/1.0
", url);

and here (s is a host)

sprintf(buffer + strlen(buffer), "Host: %s

", s);

so if the url have

512 = strlen(http:// A x504 /)

then into buffer will be put

strlen(GET HTTP/1.0
) = 15
strlen(url) = 512
strlen(Host:

)= 10
strlen(A x504) = 504

sum = 1041 bytes.

Any use of this function is a potential risk. Programs such as "ippool"
may be at risk.

- --- 2. Fix ---
NetBSD fix:
http://cvsweb.netbsd.org/bsdweb.cgi/src/dist/ipf/lib/load_http.c?only_with_tag=MAIN
- --- 3. Greets ---
Christos Zoulas

sp3x infospec chujwamwdupe pi3 and others

- --- 4. Contact ---
Author: SecurityReason.com [ Maksymilian Arciemowicz ]
Email: cxib [a.t] securityreason [d00t] com
GPG: http://securityreason.com/key/Arciemowicz.Maksymilian.gpg
http://securityreason.com
http://securityreason.pl

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