The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
None
C
There is no impact on the confidentiality of the system; the attacker does not gain the ability to read any data.
Integrity
Low
I
Modification of data is possible, but the attacker does not have control over what can be modified, or the extent of what the attacker can affect is limited. The data modified does not have a direct, serious impact on the system.
Availability
None
A
There is no impact on the availability of the system; the attacker does not have the ability to disrupt access to or use of the system.
Tenda / D-Link / TP-Link DHCP Cross Site ScriptingDocument Title:
===============
Tenda, Dlink & Tplink TD-W8961ND - DHCP XSS Vulnerability
References (Source):
====================
https://www.vulnerability-lab.com/get_content.php?id=1990
Release Date:
=============
2016-11-28
Vulnerability Laboratory ID (VL-ID):
====================================
1990
Common Vulnerability Scoring System:
====================================
3.5
Abstract Advisory Information:
==============================
The vulnerability laboratory research team discovered a persistent xss vulnerability in the Tenda, Dlink & Tplink 1.0.1 TD-W8961ND & ADSL2+ Modem Routers web-application.
Vulnerability Disclosure Timeline:
==================================
2016-11-28:Public Disclosure (Vulnerability Laboratory)
Discovery Status:
=================
Published
Exploitation Technique:
=======================
Remote
Severity Level:
===============
Medium
Technical Details & Description:
================================
Persistent cross site scripting vulnerability has been discovered in Tenda 1.0.1 ADSL Modem Routers.
The vulnerability allows remote attackers and local privileged account to inject malicious script codes
on the application-side to manipulate the router dhcp hostnames.
Attackers are able to inject malicious code into the current list of DHCP clients on view, by modifying
the DHCP hostname into valid xss payload. The execution of vulnerability occurs on the application-side
on view events. Due to our investigation, we discovered that all models with the firmware v1.x on the
web gui are affected by the security vulnerability. Remote attackers can for example make special crafted
malicious pages with POST method requests to manipulate the dhcp hostname listing and client view.
The security risk of the issue is estimated as medium with a cvss (common vulnerability scoring system) count of 3.5.
Exploitation of the vulnerability requires no privilege web-application user account and only low user interaction.
Successful exploitation of the vulnerability results in phishing attacks, session hijacking, persistent external redirect
to malicious sources and persistent manipulation of affected or connected web module context.
Request Method(s):
[+] POST
Vulnerable Module(s):
[+] DHCP Client List
[+] DHCP settings
Vulnerable Parameter(s):
[+] Hostnames
Proof of Concept (PoC):
=======================
Persistent vulnerability can be exploited by remote attackers with low privileged application user account and low user interaction.
For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue.
Manaul steps to reproduce the vulnerability ... (local)
1. Open the Router UI
2. Login as basic account
3. Open the DHCP List module via settings
4. Inject a payload to the hostnames input field
5. Save the input
6. Now the list becomes visible with all clients and the payload executes within the context
7. Successful reproduce of the vulnerability!
The following code is a bash script working on supported Linux OS to change the name of DHCP hostnames to a xss payload.
Save the file into vulnerablity.sh, then chmod +x vulnerability.sh.
PoC: Exploit
#!/bin/bash
GREEN=$(tput setaf 2 && tput bold)
BLUE=$(tput setaf 6 && tput bold)
echo $BLUE"[+] Persistent XSS DHCP Exploiter via Routers"
echo $GREEN"[+] Vulnerability founded by : Lawrence Amer "
echo -n $BLUE"[~] type XSS Payload here :"
read -e xss
echo $xss > /etc/hostname
echo $GREEN"[+]DHCP HOST NAME IS WRITTEN"
Video: https://www.youtube.com/watch?v=HUM5myJWbvc
Solution - Fix & Patch:
=======================
The xss vulnerability can be patched by a secure parse of the hostnames client parameters.
Restrict the input and disallow the usage of special chars to prevent the injection point.
Parse as well the hostnames output location in the active dhcp clients list.
Security Risk:
==============
The security risk of the persistent xss web vulnerability in the router web-application is estimate as medium. (CVSS 3.5)
Credits & Authors:
==================
Vulnerability Laboratory [Research Team] - Lawrence Amer (https://www.vulnerability-lab.com/show.php?user=Lawrence%20Amer)
Disclaimer & Information:
=========================
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